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1

GMTI radar minimum detectable velocity.  

SciTech Connect

Minimum detectable velocity (MDV) is a fundamental consideration for the design, implementation, and exploitation of ground moving-target indication (GMTI) radar imaging modes. All single-phase-center air-to-ground radars are characterized by an MDV, or a minimum radial velocity below which motion of a discrete nonstationary target is indistinguishable from the relative motion between the platform and the ground. Targets with radial velocities less than MDV are typically overwhelmed by endoclutter ground returns, and are thus not generally detectable. Targets with radial velocities greater than MDV typically produce distinct returns falling outside of the endoclutter ground returns, and are thus generally discernible using straightforward detection algorithms. This document provides a straightforward derivation of MDV for an air-to-ground single-phase-center GMTI radar operating in an arbitrary geometry.

Richards, John Alfred

2011-04-01

2

MIMO Radar Waveform Constraints for GMTI  

E-print Network

Ground moving-target indication (GMTI) provides both an opportunity and challenge for coherent multiple-input multiple-output (MIMO) radar. MIMO techniques can improve a radar's angle estimation and the minimum detectable ...

Forsythe, Keith W.

3

HRR profiling in GMTI search radar  

Microsoft Academic Search

This paper presents a high range resolution (HRR) profiling technique for generating range and Doppler profiles of multiple moving targets, while the radar is in ground moving target indicator (GMTI) search mode. To implement such a technique, it requires no a priori information on target velocity and\\/or phase, hence, it is a good candidate to be incorporated into a search

Pileih Chen

2000-01-01

4

Performance limits for exo-clutter Ground Moving Target Indicator (GMTI) radar.  

SciTech Connect

The performance of a Ground Moving Target Indicator (GMTI) radar system depends on a variety of factors, many which are interdependent in some manner. It is often difficult to 'get your arms around' the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall GMTI radar system. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the 'seek time'.

Doerry, Armin Walter

2010-09-01

5

Analysis of orthogonal waveform for spaceborne MIMO-GMTI radar  

NASA Astrophysics Data System (ADS)

The application of MIMO (Multiple input multiple output) techniques to spaceborne multichannel radar offers a number of advantages, including target detection, parameter estimation, and so on. Based on two kinds of waveforms presented in MIMO radar, a concise definition of synthetical ISLR is proposed. Through analysis of synthetical ISLR for two kinds of waveforms, it concludes that compared with orthogonal frequency division waveform, the crosscorrelation of orthogonal code waveform badly weakens the performance of spaceborne MIMO radar in GMTI (Ground moving target indication). Thus, by adopting orthogonal frequency division waveform, the basic principle of space-time-frequency adaptive processing is studied. Simulation results demonstrate the superiority of frequency division orthogonal MIMO radar in improving clutter suppression and GMTI performance.

Zou, Bo; Dong, Zhen; Du, Xiang-yu

2011-10-01

6

PodSAR: A versatile real-time SAR GMTI surveillance and targeting system  

Microsoft Academic Search

Synthetic aperture radar (SAR) and ground moving target indication (GMTI) systems from an airborne platform are in principle based on very simple concepts. The latter combines radar pulses over a short interval to extract Doppler information in order to detect ground moving targets against a clutter background. The former combines pulses over much longer intervals in a coherent manner to

M. Jahangir; D. Coe; A. P. Blake; P. G. Kealey; C. P. Moate

2008-01-01

7

Airborne GMTI using MIMO techniques  

Microsoft Academic Search

The performance of a ground moving target indicator (GMTI) radar is strongly driven by the length of the radar aperture, as longer apertures enable lower minimum detectable velocity (MDV) and better target geolocation. Multiple-input multiple-output (MIMO) techniques can enable the use of long sparse array geometries while avoiding the adverse sidelobe effects typical of such arrays. In 2009 an experiment

Joshua Kantor; Shakti K. Davis

2010-01-01

8

GMTI processing using back projection.  

SciTech Connect

Backprojection has long been applied to SAR image formation. It has equal utility in forming the range-velocity maps for Ground Moving Target Indicator (GMTI) radar processing. In particular, it overcomes the problem of targets migrating through range resolution cells.

Doerry, Armin Walter

2013-07-01

9

Test results from the AN\\/APY6 SAR\\/GMTI surveillance, tracking and targeting radar  

Microsoft Academic Search

The AN\\/APY-6 is an X-band radar developed by Northrop Grumman under ONR (Office of Naval Research) sponsorship. It was developed to provide all-speed target detection, location, tracking, imaging and exploitation. It was installed in a USA Navy NP-3 aircraft in July 1999 and continues to undergo testing and demonstration in the NP-3. This paper presents test results in the form

W. J. Miceli; L. A. Gross

2001-01-01

10

Wavelets feature aided tracking (WFAT) using GMTI\\/HRR data  

Microsoft Academic Search

This paper presents a research development of wavelets feature aided tracking, which effectively combines information from both high-resolution range (HRR) radar profiles and ground moving target indication (GMTI) radar reports. The state-of-the-art wavelets-based statistical signal processing technique: wavelets domain hidden Markov trees is used to extract robust features from HRR profiles. With the assistance of HRR wavelets features, a GMTI

Lang Hong; Shan Cong; Mark T. Pronobis; Stephen Scott

2003-01-01

11

Bias modeling and estimation for GMTI applications  

Microsoft Academic Search

This paper describes an approach to sensor bias modeling and estimation for ground target tracking applications using multiple airborne Ground Moving Target Indicator (GMTI) radar sensors. This approach was developed as part of the Precision Firecontrol Tracking (PFCT) segment of the DARPA Affordable Moving Surface Target Engagement (AMSTE) program. For airborne sensors, slowly varying platform location, heading and velocity errors

K. Kastella; B. Yeary; T. Zadra; R. Brouillard; E. Frangione

2000-01-01

12

Differential Geometry Measures of Nonlinearity for Ground Moving Target Indicator (GMTI) Filtering  

Microsoft Academic Search

The ground moving target indicator (GMTI) radar is widely used to detect, geolocate, track, and classify ground-moving targets in all weather, day-night, and cluttered conditions. The measurements of a GMTI radar are slant range, azimuth, and range-rate or Doppler. These measurements are nonlinear functions of the target state. Until recently, a quantitative measure of the degree of nonlinearity (DoN) for

Mahendra Mallick; B. F. La Scala

2005-01-01

13

GMTI-tracking and information fusion for ground surveillance  

Microsoft Academic Search

The aim of ground surveillance with airborne GMTI radar is the near real-time production of a dynamic ground picture. Since the sensors often record merely certain aspects of the situation of interest, information fusion is of particular importance. In addition, even after platform motion compensation by signal processing techniques (STAP), ground moving targets can well be masked by the clutter

Wolfgang Koch

2001-01-01

14

GMTI-tracking and information fusion for ground surveillance  

NASA Astrophysics Data System (ADS)

The aim of ground surveillance with airborne GMTI radar is the near real-time production of a dynamic ground picture. Since the sensors often record merely certain aspects of the situation of interest, information fusion is of particular importance. In addition, even after platform motion compensation by signal processing techniques (STAP), ground moving targets can well be masked by the clutter notch of the sensor. This physical phenomenon directly results from the low-DOPPLER characteristics of the targets and causes interfering fading effects that seriously affect the tracking performance/continuity. In this context a GMTI sensor model provides significant performance improvements being relevant also to sensor data fusion. The Minimum Detectable Velocity (MDV) proves to be an important sensor parameter explicitly entering into GMTI tracking. In combination with road map information or sensor data fusion the refined model can in particular alleviate the recognition of stopping targets. A numerical example quantitatively illustrates the potential gain by exploiting GMTI-modeling, road-maps, and sensor fusion.

Koch, Wolfgang

2001-11-01

15

The Earth rotation effect on a LEO L-band GMTI SBR and mitigation strategies  

Microsoft Academic Search

Space based radars (SBR) have been used to accomplish a number of civilian and military missions. Most recently, SBR concepts have been considered to perform ground moving target indication (GMTI) radar modes. Unlike airborne surveillance platforms, SBR clutter returns are affected by the high satellite velocity and Earth rotation. The phenomenology of the Earth's rotation, and its impact on clutter

Peter Zulch; Mark Davis; Larry Adzima; Robert Hancock; Sid Theis

2004-01-01

16

Simultaneous SAR and GMTI using ATI/DPCA  

NASA Astrophysics Data System (ADS)

In previous work, we presented GMTI detection and geo-location results from the AFRL Gotcha challenge data set, which was collected using a 3-channel, X-band, circular SAR system. These results were compared against GPS truth for a scripted vehicle target. The algorithm used for this analysis is known as ATI/DPCA, which is a hybrid of along-track interferometry (ATI) and the displaced phase center antenna (DPCA) technique. In the present paper the use of ATI/DPCA is extended in order to detect and geo-locate all observable moving targets in the Gotcha challenge data, including both the scripted movers and targets of opportunity. In addition, a computationally efficient SAR imaging technique is presented, appropriate for short integration times, which is used for computing an image of the scene of interest using the same pulses of data used for the GMTI processing. The GMTI detections are then overlaid on the SAR image to produce a simultaneous SAR/GMTI map.

Deming, Ross; Best, Matthew; Farrell, Sean

2014-06-01

17

Noncooperative rendezvous radar system  

NASA Technical Reports Server (NTRS)

A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

1974-01-01

18

A joint space-borne radar technology demonstration mission for NASA and the Air Force  

Microsoft Academic Search

NASA and the Air Force are currently studying joint technology demonstration concepts for large aperture Space Based Radar (SBR) systems. The mission focuses on elements of NASA's earth science enterprise strategic plan and Air Force long term needs for global airborne and ground moving target indication (GMTI and AMTI) surveillance, and represents an unprecedented multi-agency approach to scientific and technological

P. A. Rosen; M. E. Davis

2003-01-01

19

Special applications of radar systems  

Microsoft Academic Search

Developments at Dornier in radar equipment are discussed. Characteristics of the Tasyll-1 scoring system for air target simulation are examined with emphasis on the Doppler radar principle for missile location. The RADOBS-R (Radar-object shield panorama sensor) system creates a ring-shaped alarm zone around an object for protection and has an operating frequency around 14 GHz. A Synthetic Aperture Radar and

U. Knepper; R. Kremer; H. Lamprecht; R. Schotter

1980-01-01

20

New Radar and Navigation Systems  

Microsoft Academic Search

It is not the intention of this paper to give a complete coverage of all new radar and navigation systems, but to concentrate rather more on specific areas and examples where microwaves are used. Also, general coverage of the radar area is felt to be unnecessary following the invited paper given by R. Voles at Microwave 74, however recent advances

K L Fuller

1975-01-01

21

Consistency of stochastic context-free grammars and application to stochastic parsing of GMTI tracker data  

NASA Astrophysics Data System (ADS)

Conventional trackers provide the human operator with estimated target tracks. It is desirable to make higher level inference of the target behaviour/intent (e.g., trajectory inference) in an automated manner. One such approach is to use stochastic context-free grammars and the Earley-Stoelcke parsing algorithm. The problem of inference is reformulated as one of parsing. In this paper, the consistency of stochastic context-free grammars is reviewed. Some examples illustrating the constraints on SCFGs due to consistency are presented, including a toy SCFG that has been used to successfully parse real GMTI radar data.

Balaji, Bhashyam

2012-06-01

22

Road network estimation through GMTI track fusion  

NASA Astrophysics Data System (ADS)

Road networks and associated traffic flow information are topics that have an innumerable number of applications, ranging from highway planning to military intelligence. Despite the importance of these networks, archival databases that often have update rates on the order of years or even decades have historically been the main source for obtaining and analyzing road network information. This somewhat static view of a potentially changing infrastructure can cause the information to therefore be incomplete and incorrect. Furthermore, these road databases are not only static, but rarely provide information beyond a simple two-dimensional view of a road, where divided high-ways are represented in the same manner as a rural dirt road. It is for these reasons that the use of Ground Moving Target Indicator (GMTI) data and tracks to create road networks is explored. This data lends itself to being able to not only provide a single static snapshot of a network that is considered the network for years, but to provide a consistently accurate and updated changing picture of the environment. The approach employed for creating a road network from GMTI tracks includes a technique known as Continuous Dynamic Time Warping (CDTW), as well as a general fusion routine.

Scalzo, Maria; Jones, Eric; Bubalo, Adnan; Alford, Mark; Wood, Gregory

2011-06-01

23

A Through-Dielectric Radar Imaging System  

E-print Network

Through-lossy-slab radar imaging will be shown at stand-off ranges using a low-power, ultrawideband (UWB), frequency modulated continuous wave (FMCW) radar system. FMCW is desirable for through-slab applications because ...

Charvat, Gregory L.

24

Monitoring by holographic radar systems  

NASA Astrophysics Data System (ADS)

Nowadays, radar technology represents a significant opportunity to collect useful information for the monitoring and conservation of critical infrastructures. Radar systems exploit the non-invasive interaction between the matter and the electromagnetic waves at microwave frequencies. Such an interaction allows obtaining images of the region under test from which one can infer the presence of potential anomalies such as deformations, cracks, water infiltrations, etc. This information turns out to be of primary importance in practical scenarios where the probed structure is in a poor state of preservation and renovation works must be planned. In this framework, the aim of this contribution is to describe the potentialities of the holographic radar Rascan 4/4000, a holographic radar developed by Remote Sensing Laboratory of Bauman Moscow State Technical University, as a non-destructive diagnostic tool capable to provide, in real-time, high resolution subsurface images of the sounded structure [1]. This radar provides holograms of hidden anomalies from the amplitude of the interference signal arising between the backscattered signal and a reference signal. The performance of the holographic radar is appraised by means of several experiments. Preliminary tests concerning the imaging below the floor and inside wood structures are carried out in controlled conditions at the Electromagnetic Diagnostic Laboratory of IREA-CNR. After, with reference to bridge monitoring for security aim, the results of a measurement campaign performed on the Musmeci bridge are presented [2]. Acknowledgments This research has been performed in the framework of the "Active and Passive Microwaves for Security and Subsurface imaging (AMISS)" EU 7th Framework Marie Curie Actions IRSES project (PIRSES-GA-2010-269157). REFERENCES [1] S. Ivashov, V. Razevig, I. Vasilyev, A. Zhuravlev, T. Bechtel, L. Capineri, The holographic principle in subsurface radar technology, International Symposium to Commemorate the 60th Anniversary of the Invention of Holography, Springfield, Massachusetts USA, October 27-29, pp. 183-197, 2008. [2] I. Catapano, L. Crocco, A. F. Morabito, F. Soldovieri, "Tomographic imaging of holographic GPR data for non-invasive structural assessment: the Musmeci bridge investigation", Nondestructive testing and evaluation, vol. 27, pp. 229-237, 2012.

Catapano, Ilaria; Crocco, Lorenzo; Affinito, Antonio; Gennarelli, Gianluca; Soldovieri, Francesco

2013-04-01

25

Radar tracking system development  

E-print Network

The Airborne Seeker Test Bed (ASTB) is an airborne sensor testing platform operated by the Tactical Defense Systems group at MIT Lincoln Laboratory. The Instrumentation Head (IH) is a primary sensor on the ASTB. It is a ...

Chin, Yue Hann

2005-01-01

26

STAP\\/GMTI analysis using SAR data from simulated scenarios  

Microsoft Academic Search

The surveillance of ground areas is one of the essential tasks for modern manned and autonomous flying platforms. Especially a SAR\\/GMTI sensor is essential because itpsilas all weather capability, but often demands large size antennas which must be designed under aerodynamic aspects with compromises regarding the ideal SAR processing need. The customerpsilas exigency for long-term observation capabilities requires furthermore the

C. Neumann; J. Meyer-Hilberg; H. Senkowski

2008-01-01

27

Accurate 3D rigid-body target motion and structure estimation by using GMTI/HRR with template information  

NASA Astrophysics Data System (ADS)

A framework of simultaneously estimating the motion and structure parameters of a 3D object by using high range resolution (HRR) and ground moving target indicator (GMTI) measurements with template information is given. By decoupling the motion and structure information and employing rigid-body constraints, we have developed the kinematic and measurement equations of the problem. Since the kinematic system is unobservable by using only one scan HRR and GMTI measurements, we designed an architecture to run the motion and structure filters in parallel by using multi-scan measurements. Moreover, to improve the estimation accuracy in large noise and/or false alarm environments, an interacting multi-template joint tracking (IMTJT) algorithm is proposed. Simulation results have shown that the averaged root mean square errors for both motion and structure state vectors have been significantly reduced by using the template information.

Wu, Shunguang; Hong, Lang

2008-04-01

28

Kharkiv Meteor Radar System (the XX Age)  

NASA Astrophysics Data System (ADS)

Kharkiv meteor radar research are of historic value (Kolomiyets and Sidorov 2007). Kharkiv radar observations of meteors proved internationally as the best in the world, it was noted at the IAU General Assembly in 1958. In the 1970s Kharkiv meteor automated radar system (MARS) was recommended at the international level as a successful prototype for wide distribution. Until now, this radar system is one of the most sensitive instruments of meteor radars in the world for astronomical observations. In 2004 Kharkiv meteor radar system is included in the list of objects which compose the national property of Ukraine. Kharkiv meteor radar system has acquired the status of the important historical astronomical instrument in world history. Meteor Centre for researching meteors in Kharkiv is a analogue of the observatory and performs the same functions of a generator and a battery of special knowledge and skills (the world-famous studio). Kharkiv and the location of the instrument were brand points on the globe, as the place where the world-class meteor radar studies were carried out. They are inscribed in the history of meteor astronomy, in large letters and should be immortalized on a world-wide level.

Kolomiyets, S. V.

2012-09-01

29

ISAT - innovative space-based-radar antenna technology  

Microsoft Academic Search

ISAT is the innovative space-based-radar antenna technology program of the Defense Advanced Research Projects Agency (DARPA). The goal of the ISAT program is to develop antenna technology to enable tactical grade space-based GMTI (ground moving target indicator) radar - particularly from higher (-10,000 km) orbits which facilitate constellations with fewer satellites.

Joseph Guerci; E. Jaska

2003-01-01

30

A land based radar polarimeter processing system  

E-print Network

A LAND BASED RADAR POLARIMETER PROCESSING SYSTEM A Thesis by CHESTER WILLIAM KRONKE Submitted to the Graduate College of Texas AAM University in Partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1984 Major... Member M. J. McFarland Member W. B. Jones Head of Department May 1984 ABSTRACT A Land Based Radar Polarimeter Processor System. (May 1984) Chester William Kronke, B. S. , Texas ABM University Chairman of Advisory Committee: Dr. A. J. Blanchard...

Kronke, Chester William

2012-06-07

31

Radar Studies in the Solar System  

NASA Technical Reports Server (NTRS)

We aid in a study of the solar system by means of ground-based radar. We have concentrated on (1) developing the ephemerides needed to acquire radar data at Arecibo Observatory and (2) analyzing the resultant data to: test fundamental laws of gravitation; determine the size, shape, topography, and spin vectors of the targets; and study the surface properties of these objects, through their scattering law and polarization characteristics.

Shapiro, Irwin I.

1996-01-01

32

Nested Radar Systems for Remote Coastal Observations  

Microsoft Academic Search

BELL, P. S., WILLIAMS, J.J., CLARK, S., MORRIS, B.D. & VILA-CONCEJO A., 2003. Nested Radar Systems for Remote Coastal Observations. Journal of Coastal Research, SI 39 (Proccendigs of the 8th International Coastal Symposium), 438 - 489. Itajaí, SC - Brazil, ISSN 0749-0208 Advances in radar technology now allow the observation of sea surface features at multiple scales, from kilometers, down

P. S. Bell; J. J. Williams; S. Clark; B. D. Morris; A. Vila-Concejo

33

Low-Cost, High Resolution X-Band Laboratory Radar System for Synthetic Aperture Radar Applications  

Microsoft Academic Search

Entry into the field of radar cross section measurements or synthetic aperture radar (SAR) algorithm development is often difficult due to the cost of high-end precision pulsed IF or other precision radar test instruments. A low-cost entry-level alternative was developed in order to provide an intermediate step between high-end high precision radar systems and ad-hoc spare parts systems. The system

Gregory L. Charvat; L. C. Kempel

2006-01-01

34

Local motion feature aided ground moving target tracking with GMTI and HRR measurements  

Microsoft Academic Search

Tracking ground moving targets with ground moving target indicator (GMTI) measurements only could face a potential problem of losing tracks or track mingling, if the targets move together within the range of GMTI sensing uncertainty for an extended period of time. We propose a remedy for this problem by using local motion features extracted from high resolution range (HRR) profiles

Lang Hong; Ningzhou Cui; Mark Pronobis; Stephen Scott

2005-01-01

35

Phased-array radar for airborne systems  

NASA Astrophysics Data System (ADS)

Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

Tahim, Raghbir S.; Foshee, James J.; Chang, Kai

2003-09-01

36

Radar Studies in the Solar System  

NASA Technical Reports Server (NTRS)

We aid in study of the solar system by means of ground-based radar. We have concentrated on: (1) developing the ephemerides needed to acquire radar data at Arecibo Observatory and (2) analyzing the resultant data to: test fundamental laws of gravitation; determine the size , shape, topography, and spin vectors of the targets; and study the surface properties of these objects, through their scattering law and polarization characteristics. We are engaged in radar observations of asteroids and comets, both as systematically planned targets and as "targets of opportunity." In the course of the program, we have prepared ephemerides for about 80 asteroids and three comets, and the radar observations have been made or attempted at the Arecibo Observatory, in most cases successfully, and in some cases on more than one apparition. The results of these observations have included echo spectra for the targets and, in some cases, delay - Doppler images and measurements of the total round-trip delay to the targets. Perhaps the most dramatic of these results are the images obtained for asteroids (4179) Toutatis and 1989PB (Castalia), which were revealed to be double-lobed objects by the radar images. Besides these direct results, the radar observations have furnished information on the sizes and shapes of the targets through analysis of the Doppler width of the echoes as a function of time, and on the surface properties (such as composition, bulk density, and roughness) through analysis of the reflectivity and of the polarization state of the echoes. We have also refined the orbits of the observed asteroids as a result of the Doppler (and in some cases delay) measurements from the radar observations. Although the orbits of main-belt asteroids accessible to ground-based radar are quite well known from the available optical data, some near-Earth objects have been seen by radar very soon after their optical discovery (for example, 199OMF, just eight days after discovery). In such cases. the radar results ensure that the object in question can be anticipated and identified at the next apparition. We have also participated in radar studies of the terrestrial planets. The results of these studies have included both planetary topography profiles from the analysis of round-trip delays to points along the target Doppler equator and determinations of the target spin state. The latter is of special interest in the case of Venus, which is very close to, but not on, a multi-body spin-orbit resonance such that Venus rotates 12 times for every 8 Earth orbits and 13 Venus orbits. As a result, Venus presents nearly the same face toward Earth at each inferior conjunction. Our latest results confirm that the spin state of Venus is slightly off the resonance. The delay measurements from planetary 2 ranging have also been used in combination with other types of range data in testing general relativity with increasing accuracy. We have also been engaged in radar studies of planetary satellites. Using our ephemerides, Arecibo made radar observations of the Galilean satellites of Jupiter and of Mars' satellite Phobos during the favorable opposition seasons (1988-1992 for Jupiter and 1990 for Mars). An attempt was also made to observe Deimos, but without detecting an echo. In 1997, an attempt was made to observe Saturn's satellite Titan, using the newly upgraded Arecibo radar system for transmitting and the Goldstone radar for receiving, but no echo was detected. The study of satellites by radar is in many ways similar to that of asteroids. The results from these observations have included characterization of the surface properties from the reflectivity and polarization ratio, as well as (in the case of the large satellites of Jupiter) the variation of reflectivity with incidence angle.

Shaprio, Irwin I.

1998-01-01

37

Design of a miniature wideband radar experimental system  

Microsoft Academic Search

Wideband radars have been found more important both in civil and military applications. Micromation is one key technology for radars mounted at missiles, unmanned aerial vehicles (UAV), satellites, etc. The scheme of a miniature wideband radar experimental system is introduced in this paper, while the design and implementation of a wideband signal generator is analyzed in detail. The radar is

Zhang Xiao-wei; Li Ming; Zuo Lei

2011-01-01

38

Radar Performance Improvement. Angle Tracking Modification to Fire Control Radar System for Space Shuttle Rendezvous  

NASA Technical Reports Server (NTRS)

The AN/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made by a Ku-Band noncoherent pulse radar.

Little, G. R.

1976-01-01

39

Cassini radar : system concept and simulation results  

NASA Astrophysics Data System (ADS)

The Cassini mission is an international venture, involving NASA, the European Space Agency (ESA) and the Italian Space Agency (ASI), for the investigation of the Saturn system and, in particular, Titan. The Cassini radar will be able to see through Titan's thick, optically opaque atmosphere, allowing us to better understand the composition and the morphology of its surface, but the interpretation of the results, due to the complex interplay of many different factors determining the radar echo, will not be possible without an extensive modellization of the radar system functioning and of the surface reflectivity. In this paper, a simulator of the multimode Cassini radar will be described, after a brief review of our current knowledge of Titan and a discussion of the contribution of the Cassini radar in answering to currently open questions. Finally, the results of the simulator will be discussed. The simulator has been implemented on a RISC 6000 computer by considering only the active modes of operation, that is altimeter and synthetic aperture radar. In the instrument simulation, strict reference has been made to the present planned sequence of observations and to the radar settings, including burst and single pulse duration, pulse bandwidth, pulse repetition frequency and all other parameters which may be changed, and possibly optimized, according to the operative mode. The observed surfaces are simulated by a facet model, allowing the generation of surfaces with Gaussian or non-Gaussian roughness statistic, together with the possibility of assigning to the surface an average behaviour which can represent, for instance, a flat surface or a crater. The results of the simulation will be discussed, in order to check the analytical evaluations of the models of the average received echoes and of the attainable performances. In conclusion, the simulation results should allow the validation of the theoretical evaluations of the capabilities of microwave instruments, when considering topics like the surface topography, stratigraphy and identification of different materials.

Melacci, P. T.; Orosei, R.; Picardi, G.; Seu, R.

1998-10-01

40

An experimental adaptive radar array system  

NASA Astrophysics Data System (ADS)

An experimental adaptive array incorporated in an FMCW radar system is described. An FMCW radar is relatively simple and compact. It is easy to realize high range resolution and low probability of interception, and it has many promising applications in anticollision, missile guidance, navigation, and MW imaging radars. The Gram-Schmidt adaptive algorithm was used for the system and proven quite effective. For one interference case the interference null depth was better than -38 dB and the signal-to-interference ratio improvement was better than 25 dB in the entire electronic scanning region. The present algorithm produced good nulls in the interference directions; however, it produced big sidelobes in the interference directions in some cases, especially when scanning to a large aiming angle.

Gong, Y. H.

41

The instrumental principles of MST radars and incoherent scatter radars and the configuration of radar system hardware  

NASA Technical Reports Server (NTRS)

The principle of pulse modulation used in the case of coherent scatter radars (MST radars) is discussed. Coherent detection and the corresponding system configuration is delineated. Antenna requirements and design are outlined and the phase-coherent transmitter/receiver system is described. Transmit/receive duplexers, transmitters, receivers, and quadrature detectors are explained. The radar controller, integrator, decoder and correlator design as well as the data transfer and the control and monitoring by the host computer are delineated. Typical operation parameters of some well-known radars are summarized.

Roettger, Juergen

1989-01-01

42

System capability of air traffic control radar beacon system  

Microsoft Academic Search

The air traffic control radar beacon system problems and solutions to these problems are discussed. Residual problems, their extent, and their impact on future systems are described. The results of a system model are related to the possible fixes.

N. K. Shaw; A. A. Simolunas

1970-01-01

43

Optical signal processing in Radar systems  

Microsoft Academic Search

Opto-electronic components and their performances are well suited to be integrated in radar systems. In this paper, two optical architectures illustrate functions that are specific to optical processing of microwave signals, i.e., time-delay-based processing and arbitrary waveform generation of large frequency bandwidth signals.

Sylvie Tonda-Goldstein; Daniel Dolfi; Aymeric Monsterleet; Stéphane Formont; Jean Chazelas; Jean-Pierre Huignard

2006-01-01

44

High power electronic scanning millimeter-wave radar system design  

Microsoft Academic Search

Remote Sensing Solutions, Inc has received NASA funding to design a prototype millimeter-wave radar system that will lead to future generations of large aperture space-borne electronic scanning radars. A scanning millimeter-wave radar is critical tool for improving the remote sensing of the Earth and other bodies in our solar system. Low power solid-state scanning millimeter-wave radar systems cannot provide the

Stephen M. Sekelsky; James Carswell

2006-01-01

45

Tracking system for photon-counting laser radar  

E-print Network

The purpose of this thesis is to build the tracking system for a photon-counting laser radar specifically a laser radar that has the ability to perform direct and coherent detection measurement at low signal levels with ...

Chang, Joshua TsuKang

2007-01-01

46

Knowledge-based signal processing for radar ESM systems  

Microsoft Academic Search

Radar electronic support measures (ESM) systems perform the functions of threat detection and area surveillance to determine the identity and bearing of surrounding radar emitters. Automatic ESM systems incorporate a passive receiver to measure the parameters of detected radar pulses and an automatic processor to rapidly sort pulses and identify the emitters. Current processors use algorithmic processing methods which are

J. Roe; S. Cussons; A. Feltham

1990-01-01

47

A system model and inversion for synthetic aperture radar imaging  

Microsoft Academic Search

A system model and its corresponding inversion for synthetic aperture radar imaging are presented. The system model incorporates the spherical nature of a radar's radiation pattern at far field. The inverse method based on this model integrates the recorded signals at various coordinates of a translational radar (linear array) via a spatial Fourier transform. The transformed data are shown to

M. Soumekh

1990-01-01

48

The 94 GHz MMW imaging radar system  

NASA Technical Reports Server (NTRS)

The 94 GHz MMW airborne radar system that provides a runway image in adverse weather conditions is now undergoing tests at Wright-Patterson Air Force Base (WPAFB). This system, which consists of a solid state FMCW transceiver, antenna, and digital signal processor, has an update rate of 10 times per second, 0.35x azimuth resolution and up to 3.5 meter range resolution. The radar B scope (range versus azimuth) image, once converted to C scope (elevation versus azimuth), is compatible with the standard TV presentation and can be displayed on the Head Up Display (HUD) or Head Down Display (HDD) to aid the pilot during landing and takeoff in limited visibility conditions.

Alon, Yair; Ulmer, Lon

1993-01-01

49

A radar data processing and enhancement system  

NASA Technical Reports Server (NTRS)

This report describes the space position data processing system of the NASA Western Aeronautical Test Range. The system is installed at the Dryden Flight Research Facility of NASA Ames Research Center. This operational radar data system (RADATS) provides simultaneous data processing for multiple data inputs and tracking and antenna pointing outputs while performing real-time monitoring, control, and data enhancement functions. Experience in support of the space shuttle and aeronautical flight research missions is described, as well as the automated calibration and configuration functions of the system.

Anderson, K. F.; Wrin, J. W.; James, R.

1986-01-01

50

Laser radar in a system perspective  

NASA Astrophysics Data System (ADS)

As a result of recent achievements in the field of laser radars, new options are available for their operation as system components. In addition to complementing and cross-checking one another, system components can generate new synergetic values. In this article, we address various roles and functions that laser radar may perform in a complete system context. Special attention is paid to range-gated imaging ladars operating in conjunction with infrared 2D sensors providing target recognition/identification at long distances and under adverse conditions of natural illumination. The multi- or hyper-spectral features of passive IR or visible sensors may be complemented by multispectral, broadband, tunable or switchable 3D imaging ladar in order to exploit the differences in target reflectance and absorption. This option opens another possibility for multi-spectral, mid-IR ladar to differentiate targets of various types, or to enhance the visualization potential and to facilitate the scene description with small targets like mines or mine-like objects. The recently discovered specificity of Raman scattering in the perturbed sea water makes the long-standing efforts in submarine wake detection more viable. Furthermore, the combination of microwave radar and laser radar, when amplified with new achievements in the fourth generation dual-mode imaging sensors, creates the possibility of single payload configurations suitable for small platforms. Emphasis is also made of the efficiency of Doppler velocimetry for precise vehicle navigation, such as for advance cruise missile control or autonomous landing. Finally, recent advances in coherent micro-ladars for optical coherence tomography now permit the reconstruction of time resolved 3D (i.e., 4D) dynamics of blood flow in heart vessels.

Molebny, Vasyl; Kamerman, Gary; Steinvall, Ove

2011-06-01

51

Radar altimetry systems cost analysis  

NASA Technical Reports Server (NTRS)

This report discusses the application and cost of two types of altimeter systems (spaceborne (satellite and shuttle) and airborne) to twelve user requirements. The overall design of the systems defined to meet these requirements is predicated on an unconstrained altimetry technology; that is, any level of altimeter or supporting equipment performance is possible.

Escoe, D.; Heuring, F. T.; Denman, W. F.

1976-01-01

52

Waveform error analysis for bistatic synthetic aperture radar systems  

NASA Astrophysics Data System (ADS)

The signal phase histories at the transmitter, receiver, and radar signal processor in bistatic SAR systems are described. The fundamental problem of mismatches in the waveform generators for the illuminating and receiving radar systems is analyzed. The effects of errors in carrier frequency and chirp slope are analyzed for bistatic radar systems which use linear FM waveforms. It is shown that the primary effect of a mismatch in carrier frequencies is an azimuth displacement of the image.

Adams, J. W.; Schifani, T. M.

53

Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems  

PubMed Central

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

2013-01-01

54

Radar systems for the water resources mission, volume 1  

NASA Technical Reports Server (NTRS)

The state of the art determination was made for radar measurement of: soil moisture, snow, standing and flowing water, lake and river ice, determination of required spacecraft radar parameters, study of synthetic-aperture radar systems to meet these parametric requirements, and study of techniques for on-board processing of the radar data. Significant new concepts developed include the following: scanning synthetic-aperture radar to achieve wide-swath coverage; single-sideband radar; and comb-filter range-sequential, range-offset SAR processing. The state of the art in radar measurement of water resources parameters is outlined. The feasibility for immediate development of a spacecraft water resources SAR was established. Numerous candidates for the on-board processor were examined.

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

55

The SIR-C/X-SAR synthetic aperture radar system  

NASA Technical Reports Server (NTRS)

SIR-C/X-SAR, a three-frequency radar to be flown on the Space Shuttle in September 1993, is described. The SIR-C system is a two-frequency radar operating at 1250 MHz (L-band) and 5300 MHz (C-band), and is designed to get four-polarization radar imagery at multiple surface angles. The X-SAR system is an X-band imaging radar operating at 9600 MHz. The discussion covers the mission concept; system design; hardware; RF electronics; digital electronics; command, timing, and telemetry; and testing.

Jordan, Rolando L.; Huneycutt, Bryan L.; Werner, Marian

1991-01-01

56

Study to investigate and evaluate means of optimizing the radar function. [systems engineering of pulse radar for the space shuttle  

NASA Technical Reports Server (NTRS)

The investigations for a rendezvous radar system design and an integrated radar/communication system design are presented. Based on these investigations, system block diagrams are given and system parameters are optimized for the noncoherent pulse and coherent pulse Doppler radar modulation types. Both cooperative (transponder) and passive radar operation are examined including the optimization of the corresponding transponder design for the cooperative mode of operation.

1975-01-01

57

Southwest PAVE PAWS radar system: Environmental assessment  

NASA Astrophysics Data System (ADS)

This document describes the probable environmental impacts of constructing and operating a new surveillance and tracking radar that would operate between 420 and 450 MHz. Four candidate sites in the vicinity of Goodfellow Air Force Base were considered. The impact analysis found that chronic exposure of humans to the radiofrequency radiation levels outside the exclusion fence is not likely to be harmful. No hazards would be associated with fuel handling or cardiac pacemakers at ground level beyond the exclusion fence. Interference with TV reception and other home electronic systems and with UHF land mobile and amateur radios is possible, depending on the site. Handling and use of electro-explosive devices (EEDs) would be safe beyond about 1.2 miles for the basic system and about 2.4 miles for the optional, higher power system. Electromagnetic interference with radar altimeters, air navigation, and air-ground communication is not likely except at two candidate sites, where interference and EED and pacemaker hazards may exist for aircraft operating into or out of a nearby landing strip. No significant adverse biophysical impacts are expected in any location.

Everett, S. J.; Edson, W. A.; Heynick, L. N.; Pierce, S. R.; Shepherd, R. A.; Wlaklet, T. H.

1983-03-01

58

Modeling and experiments with a subsea laser radar system  

Microsoft Academic Search

Subsea laser radar has a potential for accurate 3-D imaging in water. A prototype system has been developed at Seatex A\\/S in Norway as a prestudy for the design of an underwater laser radar scanning system. Parallel to the experimental studies, a numerical radiometric model has been developed as an aid in the system design. This model simulates a raster

Morten L. Bjarnar; John O. Klepsvik; Jan E. Nilsen

1991-01-01

59

Millimeter-wave radar systems for biometric applications  

Microsoft Academic Search

Millimeter-wave and terahertz radar systems can play an important role in multimodal layered sensing systems targeted at measuring both physiological and behavioral biometric data for security and medical applications. We will describe a 228 GHz heterodyne radar system that is capable of measuring respiration rates at standoff distances of up to 50 meters and simultaneously measure respiration and heartbeat rates

Douglas T. Petkie; Erik Bryan; Carla Benton; Brian D. Rigling

2009-01-01

60

Radar systems for a polar mission, volume 1  

NASA Technical Reports Server (NTRS)

The application of synthetic aperture radar (SAR) in monitoring and managing earth resources is examined. Synthetic aperture radars form a class of side-looking airborne radar, often referred to as coherent SLAR, which permits fine-resolution radar imagery to be generated at long operating ranges by the use of signal processing techniques. By orienting the antenna beam orthogonal to the motion of the spacecraft carrying the radar, a one-dimensional imagery ray system is converted into a two-dimensional or terrain imaging system. The radar's ability to distinguish - or resolve - closely spaced transverse objects is determined by the length of the pulse. The transmitter components receivers, and the mixer are described in details.

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Komen, M. J.; Mccauley, J.; Mcmillan, S. B.; Parashar, S. K.

1977-01-01

61

Can OTH Radar Help Tsunami Warning Systems ?  

NASA Astrophysics Data System (ADS)

A series of ionospheric anomalies following the Sumatra tsunami has been reported in the scientific literature (e.g., Liu et al. 2006; DasGupta et al. 2006; Occhipinti et al. 2006). Similar anomalies were also observed after the tsunamigenic earthquake in Peru in 2001 (Artru et al., 2005) and after the recent earthquakes in Sumatra and Chile in 2007. All these anomalies show the signature in the ionosphere of tsunami-generated internal gravity waves (IGW) propagating in the neutral atmosphere over oceanic regions. Most of these ionospheric anomalies are deterministic and reproducible by numerical modeling (Occhipinti et al., 2006, 2008) via the ocean/neutral atmosphere/ionosphere coupling mechanism. In addition, the numerical modeling supplies useful helps in the estimation of expected anomalies to explore and identify new techniques to detect the tsunami signature in the ionosphere, other then GPS and altimeters. Here we present an overview of the physical coupling mechanism highlighting the advantage of OTH radar in the tsunami detection by ionospheric sounding. The large coverage of OTH radar and its sensitivity to plasma anomalies can open new perspectives in the future oceanic monitoring and tsunami warning system. [Artru et al., 2005] Geophys. J. Int., 160, 2005 [DasGupta et al., 2006] Earth Planet. Space, 35, 929-959. [Liu et al., 2006] J. Geophys. Res., 111, A05303. [Occhipinti et al., 2006] Geophys. Res. Lett., 33, L20104, 2006 [Occhipinti et al., 2008] Geophys. J. Int., 173, 3, 753-1135, 2008.

Coisson, P.; Occhipinti, G.; Roland, L.; Lognonné, P.

2008-12-01

62

A very wide frequency band pulsed/IF radar system  

NASA Technical Reports Server (NTRS)

A pulsed/IF radar for compact range radar cross section measurements has been developed which converts RF returns to a fixed IF, so that amplification and grating may be performed at one frequency. This permits the use of components which have optimal performance at this frequency which results in a corresponding improvement in performance. Sensitivity and dynamic range are calculated for this system and compared with our old radar, and the effect of pulse width on clutter level is also studied. Sensitivity and accuracy tests are included to verify the performance of the radar.

Jones, D. N.; Burnside, W. D.

1988-01-01

63

Basic characteristics of FM-CW radar systems  

NASA Astrophysics Data System (ADS)

Due to rapid technological progress in real-time signal processing, FM-CW radar systems are expected to become a more serious competitor to pulse radar systems. This paper deals with basic radar principles such as modulating waveforms and ambiguity functions characteristics. Advantages and disadvantages of FM-CW radar systems are compared to pulse radar systems. The inherent signal processing used in FM-CW radar systems allows a flexible choice of system parameters. In this context aspects like sensitivity, range and velocity resolution are discussed. It is elucidated that the use of digital processors for signal processing (frequency determination, filtering, etc.) offers the possibility to exchange dedicated hardware solutions with software implementations. Attention is paid to equipment like the antennas, diplexer, transmitter and receiver, and to isolation problems between transmitter and receiver. Results of an experimental FM-CW research radar are shown. In addition, the future prospects of FM-CW radar, with the aerial and solid-state R.F. head-end integrated, are indicated.

Ligthart, L. P.; Nieuwkerk, L. R.; Vansinttruyen, J. S.

1986-07-01

64

Evaluating a Radar-Based, Non Contact Streamflow Measurement System in the San  

E-print Network

profiler BD BoogieDopp discharge measurement system Deg. Degrees GHz GigaHertz GPR Ground penetrating radar................................................................................................................. 5 Ground-Penetrating RadarEvaluating a Radar-Based, Non Contact Streamflow Measurement System in the San Joaquin River

65

An Approach to Ground Moving Target Indication Using Multiple Resolutions of Multilook Synthetic Aperture Radar Images  

E-print Network

Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 6.1.1 MATLAB Radar Model . . . . . . . . . . . . . . . . . . . . . 126 6.1.2 Monte Carlo Simulations . . . . . . . . . . . . . . . . . . . . . 127 6.2 GMTI Using Multilook SAR Images...?cations relating Kalman ?ltering, iterative MMSE, RLS, and back projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 3.3 DWT synthesis ?lter bank tree . . . . . . . . . . . . . . . . . . . . . 57 3.4 Haar scaling function and wavelet...

Akers, Geoffrey

2009-12-15

66

The Goldstone Solar System Radar: 1988-2003 Earth-based Mars Radar Observations  

NASA Technical Reports Server (NTRS)

The Goldstone Solar System Radar (GSSR) has successfully collected radar echo data from Mars over the past 30 years. The older data provided local elevation information for Mars, along with radar scattering information with global resolution. Since the upgrade to the 70-m DSN antenna at Goldstone completed in 1986, Mars data has been collected during all but the 1997 Mars opposition. Radar data, and non-imaging delay- Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. The spatial resolution of these experiments is typically some 10 km in longitude by some 150 km in latitude. The interpretation of these parameters while limited by the complexities of electromagnetic scattering, do provide information directly relevant to geophysical and geomorphic analyses of Mars.

Haldemann, A. F. C.; Jurgens, R. F.; Slade, M. A.; Larsen, K. W.

2005-01-01

67

29. Perimeter acquisition radar building room #318, data processing system ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. Perimeter acquisition radar building room #318, data processing system area; data processor maintenance and operations center, showing data processing consoles - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

68

Analytical and computer model of a Doppler weather radar system  

Microsoft Academic Search

With advances in Doppler weather radar, severe storm and tornado detection has improved greatly. However, the resolution limitations of deployed radar systems can still limit severe storm detection. In the case of larger tornadoes, characteristic abrupt changes in wind direction can usually be detected between adjacent range-angle bins. However for smaller tornadoes, the rotating cell may be contained within one

Ryan K. Hersey; Mark A. Richards; James H. McClellan

2002-01-01

69

Reconfigurable Data Acquisition System for Weather Radar Applications  

E-print Network

, Amherst MA Abstract-- Tornado, hazardous weather and flood detection radars demand high-throughput, high-based system has been successfully integrated with a radar optimized for tornado detection and deployed, and perform various processing tasks to cast the raw data into an intelligible and meaningful format

Tessier, Russell

70

Weather Radar Control System Seidu Ibrahim; Advisor: Eric J. Knapp  

E-print Network

Weather Radar Control System Seidu Ibrahim; Advisor: Eric J. Knapp Dept. of Electrical and Computer Engineering University of Massachusetts, Amherst Abstract Weather radar is an important part of the national infrastructure that is used in producing forecasts and issuing hazardous weather warnings. Traditional weather

Mountziaris, T. J.

71

The Apollo lunar sounder radar system  

Microsoft Academic Search

The objectives of the Apollo 17 Lunar Sounder Experiment (ALSE) were to detect subsurface geologic structures, to generate a continuous lunar profile, and to image the moon a radar wavelengths. The first objective is generally impossible on Earth, but is possible on the moon because of the very low EM attenuation found in lunar rocks. A three-wavelength synthetic-aperture radar (SAR)

LEONARD J. PORCELLO; R. L. Jordan; JERRY S. ZELENKA; GARY F. ADAMS; ROGER J. PHILLIPS; WALTER E. BROWN; S. H. Ward; P. L. Jackson

1974-01-01

72

RADAR SYSTEMS FOR INFRASTRUCTURES DIAGNOSTICS: A REVIEW Ilaria Catapano, Antonio Affinito, Lorenzo Crocco, Francesco Soldovieri  

E-print Network

engineering monitoring and diagnostics. In fact, Ground Penetrating Radar and Holographic Radar are well capabilities. KEYWORDS: Ground Penetrating Radar, Holographic Radar, Microwave Imaging, Subsurface imaging - National Research Council of Italy (IREA-CNR). First of all, Ground Penetrating Radar (GPR) systems

Paris-Sud XI, Université de

73

Advanced Meteor radar at Tirupati: System details and first results  

NASA Astrophysics Data System (ADS)

An advanced meteor radar viz., Enhanced Meteor Detection Radar (EMDR) operating at 35.25 MHz is installed at Sri Venkateswara University (SVU), Tirupati (13.63oN, 79.4oE), India, in the month of August 2013. Present communication describes the need for the meteor radar at present location, system description, its measurement techniques, its variables and comparison of measured mean winds with contemporary radars over the Indian region. The present radar site is selected to fill the blind region of Gadanki (13.5oN, 79.2oE) MST radar, which covers mesosphere and lower thermosphere (MLT) region (70-110 km). By modifying the receiving antenna structure and elements, this radar is capable of providing accurate wind information between 70 and 110 km unlike other similar radars. Height covering region is extended by increasing the meteor counting capacity by modifying the receiving antenna structure and elements and hence its wind estimation limits extended below and above of 80 and 100 km, respectively. In the present study, we also made comparison of horizontal winds in the MLT region with those measured by similar and different (MST and MF radars) techniques over the Indian region including the model (HWM 07) data sets. The comparison showed a very good agreement between the overlapping altitudes (82-98 km) of different radars. Zonal winds compared very well as that of meridional winds. The observed discrepancies and limitations in the wind measurement are discussed. This new radar is expected to play important role in understanding the vertical and lateral coupling by forming a unique local network.

Sunkara, Eswaraiah; Gurubaran, Subramanian; Sundararaman, Sathishkumar; Venkat Ratnam, Madineni; Karanam, Kishore Kumar; Eethamakula, Kosalendra; Vijaya Bhaskara Rao, S.

74

Ground-penetrating-radar-assisted saturation and permeability estimation in bimodal systems  

E-print Network

Ground-penetrating-radar-assisted saturation and permeability estimation in bimodal systems Susan S from ground penetrating radar (GPR), a noninvasive, high-resolution geophysical method. The procedures

Hubbard, Susan

75

Surveillance Technology Study and Analysis. Volume IV. Considerations in the Analysis and Performance of Radar Systems.  

National Technical Information Service (NTIS)

This report presents results of studies, investigations, and technique developments which will be useful in future HF long range radar applications. This report is intended to aid the radar engineer in design and evaluation of HF radar systems. Major emph...

R. M. Davis, L. C. Widmann

1967-01-01

76

GMTI and IMINT data fusion for multiple target tracking and classification  

Microsoft Academic Search

In this paper, we propose a new approach to track multiple ground target with GMTI (Ground Moving Target Indicator) and IMINT (IMagery INtelligence) reports. This tracking algorithm takes into account road network information and is adapted to the out of sequence measurement problem. The scope of the paper is to fuse the attribute type information given by heterogeneous sensors with

Benjamin Pannetier; Jean Dezert

2009-01-01

77

A New Gaussian Mixture Algorithm for GMTI Tracking Under a Minimum Detectable Velocity Constraint  

Microsoft Academic Search

This paper introduces a new methodology to account for Doppler blind zone constraints, arising, for example, in ground moving target indicator (GMTI) tracking applications. In such problems, target measurements are suppressed when the range rate (Doppler) of the target drops below a specified threshold in magnitude (the minimum detectable velocity). The proposed method, employing Gaussian mixture approximations to the filtering

John M. C. Clark; Panagiotis-Aristidis Kountouriotis; Richard B. Vinter

2009-01-01

78

Integrated laser/radar satellite ranging and tracking system.  

PubMed

A laser satellite ranging system that is mounted upon and integrated with a microwave tracking radar is reported. The 1-pulse sec/ruby laser transmitter is attached directly to the radar's elevation axis and radiates through a new opening in the radar's parabolic dish. The laser photomultiplier tube receiver utilizes the radar's existing 20-cm diam f11 boresight telescope and observes through a similar symmetrically located opening in the dish. The laser system possesses separate ranging system electronics but shares the radar's timing, computer, and data handling[equation]recording systems. The basic concept of the laser[equation]radar is outlined together with a listing of the numerous advantages over present singular laser rangefinding systems. The developmental laser hardware is described along with preliminary rangefinding results and expectations. The prototype system was assembled to investigate the feasibility of such systems and aid in the development of detailed specifications for an operational system. Both the feasibility and desirability of such systems integrations have been adequately demonstrated. PMID:20134689

Hoge, F E

1974-10-01

79

Radar systems for the water resources mission, volume 2  

NASA Technical Reports Server (NTRS)

The application of synthetic aperture radar (SAR) in monitoring and managing earth resources was examined. The function of spaceborne radar is to provide maps and map imagery to be used for earth resource and oceanographic applications. Spaceborne radar has the capability of mapping the entire United States regardless of inclement weather; however, the imagery must have a high degree of resolution to be meaningful. Attaining this resolution is possible with the SAR system. Imagery of the required quality must first meet mission parameters in the following areas: antenna patterns, azimuth and range ambiguities, coverage, and angle of incidence.

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

80

The Apollo Lunar Sounder radar system  

NASA Technical Reports Server (NTRS)

The objectives of the Apollo 17 Lunar Sounder Experiment (ALSE) were to detect subsurface geologic structures, to generate a continuous lunar profile, and to image the moon at radar wavelengths. A three-wavelength synthetic-aperture radar (SAR) operating at 60, 20, and 2 m wavelengths was designed to attain these objectives. The design choices reflected a balance of scientific requirements versus Apollo mission and hardware constraints. The radar data from the lunar mission were recorded on photographic film in a conventional SAR format, and were returned to earth for processing. A combination of optical and digital processing and exploitation techniques was applied to the scientific interpretation of the data. Some preliminary results from the lunar mission have been obtained.

Porcello, L. J.; Zelenka, J. S.; Adams, G. F.; Jackson, P. L.; Jordan, R. L.; Phillips, R. J.; Brown, W. E., Jr.; Ward, S. H.

1974-01-01

81

Bistatic radar sea state monitoring system design  

NASA Technical Reports Server (NTRS)

Remote measurement of the two-dimensional surface wave height spectrum of the ocean by the use of bistatic radar techniques was examined. Potential feasibility and experimental verification by field experiment are suggested. The required experimental hardware is defined along with the designing, assembling, and testing of several required experimental hardware components.

Ruck, G. T.; Krichbaum, C. K.; Everly, J. O.

1975-01-01

82

Spaceborne Doppler Precipitation Radar: System Configurations and Performance Analysis  

NASA Technical Reports Server (NTRS)

Knowledge of the global distribution of the vertical velocity of precipitation is important in in the study of energy transportation in the atmosphere, the climate and weather. Such knowledge can only be directly acquired with the use of spaceborne Doppler precipitation radars. Although the high relative speed of the radar with respect to the rainfall particles introduces significant broadening in the Doppler spectrum, recent studies have shown that the average vertical velocity can be measured to acceptable accuracy levels by appropriate selection of radar parameters. Furthermore, methods to correct for specific errors arising from NUBF effects and pointing uncertainties have recently been developed. In this paper we will present the results of the trade studies on the performances of a spaceborne Doppler radar with different system parameters configurations.

Tanelli, Simone; Im, Eastwood

2004-01-01

83

2003 Mercury Computer Systems, Inc. Beamforming for Radar  

E-print Network

© 2003 Mercury Computer Systems, Inc. Beamforming for Radar Systems on COTS Heterogeneous ComputingHeterogeneous Computing PlatformsPlatforms Jeffrey A. Rudin Mercury Computer Systems, Inc. High Performance Embedded Computing (HPEC) Conference September 23, 2003 #12;2© 2003 Mercury Computer Systems, Inc. Outline

Kepner, Jeremy

84

Review of the NASA\\/JPL airborne synthetic aperture radar system  

Microsoft Academic Search

AIRSAR has served as a test-bed for both imaging radar techniques and radar technologies for over a decade. In fact, the polarimetric, cross-track interferometric, and along-track interferometric radar techniques were all developed using AIRSAR. We present the up-to-date system configuration, the expected performance and data accuracy in the standard radar modes.

Yunling Lou

2002-01-01

85

29 CFR 1915.85 - Vessel radar and communication systems.  

(b) The employer shall secure each vessel's radar and communication system so it is incapable of energizing or emitting radiation before any employee begins work: (1) On or in the vicinity of the system; (2) On or in the vicinity of a system equipped with a dummy load;...

2014-07-01

86

29 CFR 1915.85 - Vessel radar and communication systems.  

Code of Federal Regulations, 2013 CFR

(b) The employer shall secure each vessel's radar and communication system so it is incapable of energizing or emitting radiation before any employee begins work: (1) On or in the vicinity of the system; (2) On or in the vicinity of a system equipped with a dummy load;...

2013-07-01

87

Protection of radar systems against nearby or direct lightning strokes  

Microsoft Academic Search

The paper deals with the characteristics of a lightning protection system (LPS) for a fixed and a mobile radars. The LPS design includes external (LPE) and internal (LPI) system as well as protection measures against lightning electromagnetic pulse (LEMP) of internal electrical and electronic systems (i.e. air terminations, down conductors, earthing arrangement, internal equipotential bonding. cable routing and shielding and

A. Annunziata; A. Dominicis; G. Antonini; A. Orlandi; F. Fiamingo; C. Mazzetti

2008-01-01

88

Quantitative data quality metrics for 3D laser radar systems  

NASA Astrophysics Data System (ADS)

Several quantitative data quality metrics for three dimensional (3D) laser radar systems are presented, namely: X-Y contrast transfer function, Z noise, Z resolution, X-Y edge & line spread functions, 3D point spread function and data voids. These metrics are calculated from both raw and/or processed point cloud data, providing different information regarding the performance of 3D imaging laser radar systems and the perceptual quality attributes of 3D datasets. The discussion is presented within the context of 3D imaging laser radar systems employing arrays of Geiger-mode Avalanche Photodiode (GmAPD) detectors, but the metrics may generally be applied to linear mode systems as well. An example for the role of these metrics in comparison of noise removal algorithms is also provided.

Stevens, Jeffrey R.; Lopez, Norman A.; Burton, Robin R.

2011-06-01

89

Development of land based radar polarimeter processor system  

NASA Astrophysics Data System (ADS)

The processing subsystem of a land based radar polarimeter was designed and constructed. This subsystem is labeled the remote data acquisition and distribution system (RDADS). The radar polarimeter, an experimental remote sensor, incorporates the RDADS to control all operations of the sensor. The RDADS uses industrial standard components including an 8-bit microprocessor based single board computer, analog input/output boards, a dynamic random access memory board, and power supplis. A high-speed digital electronics board was specially designed and constructed to control range-gating for the radar. A complete system of software programs was developed to operate the RDADS. The software uses a powerful real time, multi-tasking, executive package as an operating system. The hardware and software used in the RDADS are detailed. Future system improvements are recommended.

Kronke, C. W.; Blanchard, A. J.

1983-09-01

90

A fully photonics-based coherent radar system  

NASA Astrophysics Data System (ADS)

The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution. Today's digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves, and the detection of such signals and their precise direct digitization without downconversion. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system.

Ghelfi, Paolo; Laghezza, Francesco; Scotti, Filippo; Serafino, Giovanni; Capria, Amerigo; Pinna, Sergio; Onori, Daniel; Porzi, Claudio; Scaffardi, Mirco; Malacarne, Antonio; Vercesi, Valeria; Lazzeri, Emma; Berizzi, Fabrizio; Bogoni, Antonella

2014-03-01

91

Raindrop size distributions and radar reflectivity-rain rate relationships for radar hydrology Hydrology and Earth System Sciences, 5(4), 615627 (2001) EGS  

E-print Network

Raindrop size distributions and radar reflectivity-rain rate relationships for radar hydrology 615 Hydrology and Earth System Sciences, 5(4), 615­627 (2001) © EGS Raindrop size distributions and radar reflectivity­rain rate relationships for radar hydrology* Remko Uijlenhoet1 Sub-department Water Resources

Boyer, Edmond

92

Deterministic Approach for Spatial Diversity Analysis of Radar Systems Using Near-Field Radar Cross Section of a Metallic Plate  

Microsoft Academic Search

A deterministic analysis of spatial diversity is presented in connection with radar systems. A numerical technique based on physical optics is used for our analysis. Contrary to statistical models, the proposed technique takes into account accurate near-field radar cross section of the target, and radiation characteristics of transmitting and receiving antennas. The power scattered by the target and received by

Ramin Deban; Halim Boutayeb; Ke Wu; Jean Conan

2010-01-01

93

14 CFR Appendix G to Part 121 - Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment and...  

Code of Federal Regulations, 2011 CFR

...Doppler Radar and Inertial Navigation System (INS): Request...Doppler Radar or Inertial Navigation System must submit...program curriculum for initial approval under § 121...Training programs. The initial training program for Doppler Radar and Inertial Navigation Systems must...

2011-01-01

94

14 CFR Appendix G to Part 121 - Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment and...  

Code of Federal Regulations, 2012 CFR

...Doppler Radar and Inertial Navigation System (INS): Request...Doppler Radar or Inertial Navigation System must submit...program curriculum for initial approval under § 121...Training programs. The initial training program for Doppler Radar and Inertial Navigation Systems must...

2012-01-01

95

14 CFR Appendix G to Part 121 - Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment and...  

Code of Federal Regulations, 2013 CFR

...Doppler Radar and Inertial Navigation System (INS): Request...Doppler Radar or Inertial Navigation System must submit...program curriculum for initial approval under § 121...Training programs. The initial training program for Doppler Radar and Inertial Navigation Systems must...

2013-01-01

96

14 CFR Appendix G to Part 121 - Doppler Radar and Inertial Navigation System (INS): Request for Evaluation; Equipment and...  

...Doppler Radar and Inertial Navigation System (INS): Request...Doppler Radar or Inertial Navigation System must submit...program curriculum for initial approval under § 121...Training programs. The initial training program for Doppler Radar and Inertial Navigation Systems must...

2014-01-01

97

Wearable System-on-a-Chip Pulse Radar Sensors for the Health Care: System Overview  

Microsoft Academic Search

A new system-on-a-chip radar sensor for next generation wearable wireless interface applied to the human health-care and safeguard is presented. The system overview is provided and a summary of the feasibility study of the radar sensor is presented. In detail, the overall system consists of a radar sensor for detecting the heart and breath rates and a low-power IEEE 802.15.4

Domenico Zito; Domenico Pepe; Bruno Neri; Danilo De Rossi; Antonio Lanata

2007-01-01

98

78. View of radar systems technical publication library, transmitter building ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

78. View of radar systems technical publication library, transmitter building no. 102, second floor. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

99

Most people immediately recognize the importance of radar systems to  

E-print Network

, which provides forecasts and emergency weather information. Yet, the National Aeronautics and Space. In addition, an MPAR system's surveillance capabilities would likely exceed those of current radar systems microwave circuit board mate- rials and are constructed using standard commercial manufacturing techniques

Reuter, Martin

100

Knowledge-based signal processing for radar ESM systems  

NASA Astrophysics Data System (ADS)

Radar electronic support measures (ESM) systems perform the functions of threat detection and area surveillance to determine the identity and bearing of surrounding radar emitters. Automatic ESM systems incorporate a passive receiver to measure the parameters of detected radar pulses and an automatic processor to rapidly sort pulses and identify the emitters. Current processors use algorithmic processing methods which are inflexible and do not fully utilize available sources of a priori information. The paper discusses the role of knowledge-based processing methods and how they may be applied to the key ESM signal-processing functions of deinterleaving, merge and emitter identification. ESM processors are required to sort input pulse data streams exceeding one million pulses per second and minimize the reporting latency of new emitters. The paper further discusses the requirements to achieve real-time operation of knowledge-based ESM processing techniques.

Roe, J.; Cussons, S.; Feltham, A.

1990-10-01

101

47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Technical requirements for ground...radars and wall imaging systems. 15.509 Section...Operation § 15.509 Technical requirements for ground...radars and wall imaging systems. (a) The UWB...

2010-10-01

102

47 CFR 15.515 - Technical requirements for vehicular radar systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Technical requirements for vehicular radar systems. 15.515 Section 15.515...Ultra-Wideband Operation § 15.515 Technical requirements for vehicular radar systems. (a) Operation...

2010-10-01

103

47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section...Operation § 15.509 Technical requirements for ground penetrating radars and wall imaging systems. (a) The...

2012-10-01

104

47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section...Operation § 15.509 Technical requirements for ground penetrating radars and wall imaging systems. (a) The...

2013-10-01

105

47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Technical requirements for ground penetrating radars and wall imaging systems. 15.509 Section...Operation § 15.509 Technical requirements for ground penetrating radars and wall imaging systems. (a) The...

2011-10-01

106

Doppler Radar Error Equations for Damped Inertial Navigation System Analysis  

Microsoft Academic Search

The use of Doppler radar measurements to provide velocity damping for an aircraft inertial navigation system is considered. Three different Doppler antenna configurations are examined: two-axis stabilized, azimuth stabilized, and data stabilized antennas. A general reference velocity error equation is presented and appropriately evaluated for each of the Doppler configurations. Specific elements of the error equations are examined and physically

Joseph Kasper; Raymond Nash

1975-01-01

107

Teaching an Undergraduate Radar Systems Course: A Global Perspective  

Microsoft Academic Search

This paper focuses on the global implementation of a unique course in radar systems, which is developed and taught for several years to the undergraduate students in electrical engineering and avionics majors at Saint Louis University. It also discusses the challenge of offering such a course, and proposes a course curriculum that is specifically tailored for undergraduate students from global

Habib Rahman; Beshara Sholy

2002-01-01

108

Radar Cross Section measurements of small Unmanned Air Vehicle Systems in non-cooperative field environments  

Microsoft Academic Search

The growing use of unmanned air vehicle systems (UAVS) is drawing increased interest in their radar signature to search and track radars. Because it is not always possible to transport UAVS to radar cross section (RCS) measurement facilities, a portable RCS measurement system has been developed and demonstrated in non-cooperative field environments. This paper presents the portable RCS measurement system

A. Bati; D. Hilliard

2009-01-01

109

"A Functional Design and System Architecture of a Control System for a Weather Radar"  

E-print Network

"A Functional Design and System Architecture of a Control System for a Weather Radar" Seidu Ibrahim Faculty Mentor: Eric Knapp Weather radars operate by transmitting pulses of very high microwave energy antenna scan, a three dimensional view of the surrounding atmosphere is created. Traditional weather

Mountziaris, T. J.

110

Coherent 1.06-um cw laser radar system  

Microsoft Academic Search

A coherent 1.06micrometers all solid state laser radar system is proposed. The system uses a LD pumped monolithic Nd:YAG ring laser as the source. Very stable output of the laser is linearly frequency modulated by an acousto-optic modulator. The wide modulation bandwidth is achieved by cascading two Bragg cells, in which each cell produces half of the total bandwidth. In

Su Hui Yang; Ke Ying Wu; Chang Ming Zhao; Guang Hui Wei

2000-01-01

111

Radio Aurora Explorer: Mission science and radar system  

NASA Astrophysics Data System (ADS)

The Radio Aurora Explorer (RAX) satellite is the first of several satellites funded under the NSF CubeSat-based Space Weather and Atmospheric Research Program. RAX is a ground-to-space bi-static radar remote sensing experiment designed to measure and understand the causes of meter-scale ionospheric irregularities. Also known as field-aligned irregularities (FAI), such non-thermal, coherent fluctuations of electron density occur in response to strong ionospheric flows or plasma density gradients during geomagnetic disturbances and are considered a space weather concern due to disruption to communication and navigation signals. The RAX CubeSat was launched in November 2010 and conducted a single experiment in coordination with the Poker Flat Incoherent Scatter Radar. Due to geophysical inactivity, e.g., lack of strong ionospheric electric fields and low ionospheric densities, no FAI were expected or observed. However, the radar receiver payload operation was successfully demonstrated, including the capability to sense signals as low as -110 dBm, the capability of transmitter-receiver synchronization and accurate ranging, processing of 1.2 GB of raw radar data on board in less than 1 hour, and the downlink of the science results within three-four passes. Analysis of the payload data shows that the noise level is sufficiently low. Although the interference level is a concern, it does not appear to significantly limit the measurements. Toward the end of December 2010, the solar power system gradually degraded and the mission terminated in early February 2011 after prolonged loss of contact with the satellite. Meanwhile, RAX II was launched in October 2011 to a polar orbit. This paper describes the RAX science and radar system and presents the results from the first experiment conducted.

Bahcivan, H.; Cutler, J. W.

2012-04-01

112

Project Report X-band Radar Wave Observation System  

E-print Network

of Radar Images ...................................... 9 2.3. Personal Computer ................................ 25 Chapter 4. Software for Data Analysis ...................................................... 31 4 ................................................. 48 Chapter 5. Data Process for Radar Images .................................................. 52 5

Newman, Michael C.

113

A new modeling of radar target based on multi-scattering centers and implementation of radar target HWIL simulation system  

Microsoft Academic Search

This paper focus on the involved theoretical characteristics, modeling of the radar target especially the near field target considering the influence of JEM (jet engine modulation) and implementation of near field radar target HWIL (hardware-in-the-loop) simulation system and proposes a new modeling method based on multi-scattering centers. Multi-scattering centers modeling method is based on decomposition of components of the near

Qi Zhao; Yuanchun Fei; Ning Chen; Baoxue Li

2008-01-01

114

Clutter cancellation techniques for use in a space-based radar system  

Microsoft Academic Search

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent on the clutter cancellation technique employed. To thoroughly understand the nature of clutter so as to efficiently and effectively design and develop clutter cancellation techniques, fundamental mathematical relationships dealing with radar signal representation, probability theory, detection and estimation theory

J. Devenuto

1983-01-01

115

Instruments and Methods An integrated lightweight ice-penetrating radar system  

E-print Network

Instruments and Methods An integrated lightweight ice-penetrating radar system Laurent MINGO,1 thick in machine-based surveys in Iceland. 1. INTRODUCTION Ice-penetrating radar is one of the most (Steinhage and others, 1999), but ground-based radars remain in demand for use in surveys of modest spatial

Flowers, Gwenn

116

Modeling and simulation of CO2 laser initiative imaging radar system  

Microsoft Academic Search

In all of precise guidance technology, imaging laser radar guidance technology is one of the most important orientations in the future development of precision guidance. The laser radar is a radar system adopting laser photosource and operating on optical band and the laser heterodyne measurement is a detection technique with high sensitivity. It can advance the hitting precision, the ability

Haiyan Li; Youjin He; Min Zhu; Yanzhi Dong

2007-01-01

117

The Processing of Altimetric Data (PAD) System for Cassini RADAR.  

NASA Astrophysics Data System (ADS)

This paper describes the Cassini RADAR PAD System, which has been designed and developed in the frame of Cassini-Huygens, a joint NASA/ESA/ASI mission to Saturn and its moons, responding to ASI request to process the data collected by the Cassini RADAR Altimeter. The PAD System contains the HW and SW operational tools necessary to evaluate the instrument performances, to process the raw data, and finally to visualize digital maps of Titan's surface by using the data acquired by the Cassini RADAR during close flybys of Titan. Titan, the largest moon of Saturn, is the only satellite in the solar system to host an appreciable atmosphere. The smoggy haze that completely envelops the satellite is composed mostly of nitrogen, aerosols and a variety of hydrocarbons, produced as atmospheric methane is destroyed by sunlight. To date, many scientists have speculated that the surface could probably contain solid, liquid and muddy material creating features such as lakes, seas, or rivers, and it should be mostly coated with sticky brown organic condensate rained down from the atmosphere. The PAD System, actually installed and operated at Alcatel Alenia Space Italia premises in Rome will be able to grant the provision of altimetric data for at least the nominal 4-years mission lifetime (i.e. 45 envisaged flybys of Titan).

Alberti, G.; Catallo, C.; Festa, L.; Flamini, E.; Orosei, R.; Papa, C.; Picardi, G.; Seu, R.; Spataro, F.; Vingione, G.

118

Target localization accuracy gain in MIMO radar-based systems  

Microsoft Academic Search

This paper presents an analysis of target localization accuracy, attainable by the use of multiple-input multiple-output (MIMO) radar systems, configured with multiple transmit and receive sensors, widely distributed over an area. The Cramer-Rao lower bound (CRLB) for target localization accuracy is developed for both coherent and noncoherent processing. Coherent processing requires a common phase reference for all transmit and receive

Hana Godrich; Alexander M. Haimovich; Rick S. Blum

2010-01-01

119

Robust radar detection of GMTI targets with STAP D. M. Carrington and Dr. P. G. Kealey  

E-print Network

performance given by the Probability of Detection (PD). Other capabilities such as geolocation, recognition processing can be performed either before Fast Fourier Transform (FFT) (pre-Doppler) or after FFT (post- Doppler). A full description of the mathematics of STAP is beyond the scope of this paper

Haddadi, Hamed

120

The Ground System of the SHAllow RADar (SHARAD) Experiment.  

NASA Astrophysics Data System (ADS)

A primary scope of Mars exploration is the research of underground water. Knowledge of water and ice quantity and distribution has enourmous impacts on our understanding on gelogic, hydrologic and climate evolution of Mars and of its origin. To this aim, high resolution observations of geophysical parameters can address these items expecially when conducted by means of penetrating radar systems orbiting around the planet, due to their intrinsic capabilities to detect underground water/ice. In this framework, SHARAD (SHAllow RADar) on-board NASA's Mars Reconnaissance Orbiter (MRO) assumes a key role within Mars exploration activities. SHARAD is a wideband radar sounder transmitting at a centre frequency of 20 MHz within 15-25 MHz spectral range. SHARAD has been launched on August '05 and will start its nominal observation phase from November '06. To guarantee its operations, commands and data analysis and processing, the SHARAD Ground Data System (GDS) has been designed and developped. SHARADA GDS is a ground system equipped with ad-hoc sw tools to allow instrument operations and data processing during the two-year mission duration. The present paper is focused on SHARAD GDS description of its architecture and of instrument planning, commanding and data processing sofwtare tools.

Alberti, G.; Biccari, D.; Bortone, B.; Caramiello, C.; Catallo, C.; Croce, A.; Dinardo, S.; Flamini, E.; Guelfi, M.; Masdea, A.; Mattei, S.; Orosei, R.; Papa, C.; Pica, G.; Picardi, G.; Salzillo, G.; Santovito, M. R.; Seu, R.

121

The effect of radar transmitter noise on system performance in clutter  

NASA Astrophysics Data System (ADS)

The generation and characteristics of the noise and spurious modulations which may be found on the output of a radar transmitter are discussed. Simple clutter-cancelling systems and the general class of filter-bank radar are considered. The pulse-Doppler radar is examined in detail with attention to the problem of clutter rejections in the range-ambiguous mode of operation. A hypothetical radar requirement is analyzed to show how the radar requirement is translated into a specification for the spectral noise of the transmitter. Measures such as pulse compression and receiver limiting are also discussed.

Cooper, D.

1980-12-01

122

Mapping tree root systems with ground-penetrating radar.  

PubMed

A ground-penetrating radar (GPR) technique was used to study the three-dimensional distribution of root systems of large (DBH = 14 to 35 cm) oak trees (Quercus petraea (Mattusch.) Liebl.) in relatively dry, luvisoil on loamy deluvium and weathered granodiorite. We used a pulse EKKO 1000 GPR system, a profile grid of 0.25 x 0.25 meters, at 0.05 m intervals, and a signal frequency of 450 MHz, to assure resolution of about 3 cm in both directions (further increases in resolution up to 1 cm are possible with the system). Coarse root density was 6.5 m m(-2) of stand area and 3.3 m m(-3) of soil volume. Maximum rooting depth of the experimental oaks was 2 m, and the root ground plan was significantly larger (about 1.5 times) than the crown ground plan. Based on earlier studies of Quercus robur L. from floodplain forests, where the extent of the root systems was much smaller (root ground plan:crown ground plan ratio of 0.6), we conclude that the high root ground plan:crown ground plan ratio indicates less favorable conditions of water supply at the experimental site than in the floodplain forest. The ground-penetrating radar system is noninvasive and allows relatively rapid and repeated measurements of the distribution of coarse root systems of trees. PMID:12651592

Hruska, Jiri; Cermák, Jan; Sustek, Svatopluk

1999-02-01

123

Multi-agent system for target-adaptive radar tracking  

NASA Astrophysics Data System (ADS)

Sensor systems such as distributed sensor networks and radar systems are potentially agile - they have parameters that can be adjusted in real-time to improve the quality of data obtained for state-estimation and decision-making. The integration of such sensors with cyber systems involving many users or agents permits greater flexibility in choosing measurement actions. This paper considers the problem of selecting radar waveforms to minimize uncertainty about the state of a tracked target. Past work gave a tractable method for optimizing the choice of measurements when an accurate dynamical model is available. However, prior knowledge about a system is often not precise, for example, if the target under observation is an adversary. A multiple agent system is proposed to solve the problem in the case of uncertain target dynamics. Each agent has a different target model and the agents compete to explain past data and select the parameters of future measurements. Collaboration or competition between these agents determines which obtains access to the limited physical sensing resources. This interaction produces a self-aware sensor that adapts to changing information requirements.

O'Connor, Alan C.

2012-06-01

124

Radar data processing using a distributed computational system  

NASA Astrophysics Data System (ADS)

This research specifies and validates a new concurrent decomposition scheme, called Confined Space Search Decomposition (CSSD), to exploit parallelism of Radar Data Processing algorithms using a Distributed Computational System. To formalize the specification, we propose and apply an object-oriented methodology called Decomposition Cost Evaluation Model (DCEM). To reduce the penalties of load imbalance, we propose a distributed dynamic load balance heuristic called Object Reincarnation (OR). To validate the research, we first compare our decomposition with an identified alternative using the proposed DCEM model and then develop a theoretical prediction of selected parameters. We also develop a simulation to check the Object Reincarnation Concept.

Mota, Gilberto F.

1992-06-01

125

A review of CFAR detection techniques in radar systems  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to discuss the problem of achieving constant false alarm rate (CFAR) operation in radar systems and the techniques used for this purpose. First, the characteristics of noncoherent clutter in both space and time domains are assessed. Attention is then focused on the two main approaches to CFAR detection, spatial adaptive thresholding and temporal adaptive thresholding. For each approach, a number of currently used techniques are reviewed. Performance evaluation and comparison between the two classes of devices also are considered. Other CFAR techniques based on coherent processing are outlined and discussed.

Farina, A.; Studer, F. A.

1986-09-01

126

A multiparameter radar examination of a mesoscale convective system  

NASA Technical Reports Server (NTRS)

Differences in the rainrates of various cells embedded within a mesoscale convective system on July 13, 1986 during the Cooperative Huntsville Meteorological experiment are examined. The NCAR CP2 S-band polarimetric radar deployed near Huntsville, Alabama, is used to characterize the rainfall field. Rainfall estimates are compared and contrasted using the single-parameter Marshall and Palmer (1948) method with the Illingworth and Caylor (1989) dual-polarization technique (ILC). The primary differences in the rainrate estimates are shown to be associated with the differences in the drop size distributions, derived from the ILC technique, that occur within the various storms.

Wright, P. D.; Goodman, S. J.

1991-01-01

127

Traffic Surveillance System Based on a High-Resolution Radar  

Microsoft Academic Search

Traffic surveillance is an important civilian application of radars. The current high-resolution radars give new opportunities so that the traffic application may be redefined. In this paper, a traffic scenario with a high-resolution radar is presented. A range-bin alignment method, the Global Range Alignment, which comes from the focusing techniques in inverse synthetic aperture radar, is applied to obtain further

J. M. Munoz-Ferreras; F. Perez-Martinez; J. Calvo-Gallego; A. Asensio-Lopez; B. P. Dorta-Naranjo; A. Blanco-Del-Campo

2008-01-01

128

The Advanced Simulation System for MMW Imaging Radar Seeker onboard Air-to-air Missile  

Microsoft Academic Search

Millimeter wave (MMW) radar is booming in application to target seeker onboard the air-to-air missile (AAM), which has the capability to obtain all-weather radar images for auto target recognition (ATR) and intelligent active homing guidance. An advanced simulation system for MMW imaging radar seekers of AAM was introduced in this paper. The system is composed of parameter initialization module, signal

Sun Yumeng; C. Jie; G. Caihong; S. Bing; Z. Yinqing

2006-01-01

129

An Experimental Study on Using Electronically Scanning Microwave Radar Systems on Surface Mining Machines  

Microsoft Academic Search

Using a series-model of an automotive short range radar sensor (SRR) and a recently completed experimental radar system, field tests have been performed in a surface mine. It was examined, to what extent low-cost electronically scanning radar sensors can provide useful data for assistance systems in large scale mining machines. The series SRR sensor using mono-pulse principles for cross range

K. Nienhaus; R. Winkel; W. Mayer; A. Gronau; W. Menzel

2007-01-01

130

MARA (Multimode Airborne Radar Altimeter) system documentation. Volume 1: MARA system requirements document  

NASA Technical Reports Server (NTRS)

The Multimode Airborne Radar Altimeter (MARA), a flexible airborne radar remote sensing facility developed by NASA's Goddard Space Flight Center, is discussed. This volume describes the scientific justification for the development of the instrument and the translation of these scientific requirements into instrument design goals. Values for key instrument parameters are derived to accommodate these goals, and simulations and analytical models are used to estimate the developed system's performance.

Parsons, C. L. (editor)

1989-01-01

131

Synthetic aperture radar processing system for search and rescue  

NASA Astrophysics Data System (ADS)

Synthetic aperture radar (SAR) is uniquely suited to help solve the search and rescue problem since it can be utilized either day or night and through both dense fog or thick cloud cover. This paper describes the search and rescue data processing system (SARDPS) developed at Goddard Space Flight Center. SARDPS was developed for the Search and Rescue Mission Office in order to conduct research, development, and technology demonstration of SAR to quickly locate small aircraft which have crashed in remote areas. In order to effectively apply SAR to the detection of crashed aircraft several technical challenges needed to be overcome. These include full resolution SAR image formation using low frequency radar appropriate for foliage penetration, the application of autofocusing for SAR motion compensation in the processing system, and the development of sophisticated candidate crash site detection algorithms. In addition, the need to dispatch rescue teams to specific locations requires precise SAR image georectification and map registration techniques. The final end-to-end processing system allows for raw SAR phase history data to be quickly converted to georeferenced map/image products with candidate crash site locations identified.

Huxtable, Barton D.; Jackson, Christopher R.; Mansfield, Arthur W.; Rais, Houra

1997-06-01

132

A videoSAR mode for the x-band wideband experimental airborne radar  

NASA Astrophysics Data System (ADS)

DRDC has been involved in the development of airborne SAR systems since the 1980s. The current system, designated XWEAR (X-band Wideband Experimental Airborne Radar), is an instrument for the collection of SAR, GMTI and maritime surveillance data at long ranges. VideoSAR is a land imaging mode in which the radar is operated in the spotlight mode for an extended period of time. Radar data is collected persistently on a target of interest while the aircraft is either flying by or circling it. The time span for a single circular data collection can be on the order of 30 minutes. The spotlight data is processed using synthetic apertures of up to 60 seconds in duration, where consecutive apertures can be contiguous or overlapped. The imagery is formed using a back-projection algorithm to a common Cartesian grid. The DRDC VideoSAR mode noncoherently sums the images, either cumulatively, or via a sliding window of, for example, 5 images, to generate an imagery stream presenting the target reflectivity as a function of viewing angle. The image summation results in significant speckle reduction which provides for increased image contrast. The contrast increases rapidly over the first few summed images and continues to increase, but at a lesser rate, as more images are summed. In the case of cumulative summation of the imagery, the shadows quickly become filled in. In the case of a sliding window, the summation introduces a form of persistence into the VideoSAR output analogous to the persistence of analog displays from early radars.

Damini, A.; Balaji, B.; Parry, C.; Mantle, V.

2010-04-01

133

Fiber optic coherent laser radar 3D vision system  

SciTech Connect

This CLVS will provide a substantial advance in high speed computer vision performance to support robotic Environmental Management (EM) operations. This 3D system employs a compact fiber optic based scanner and operator at a 128 x 128 pixel frame at one frame per second with a range resolution of 1 mm over its 1.5 meter working range. Using acousto-optic deflectors, the scanner is completely randomly addressable. This can provide live 3D monitoring for situations where it is necessary to update once per second. This can be used for decontamination and decommissioning operations in which robotic systems are altering the scene such as in waste removal, surface scarafacing, or equipment disassembly and removal. The fiber- optic coherent laser radar based system is immune to variations in lighting, color, or surface shading, which have plagued the reliability of existing 3D vision systems, while providing substantially superior range resolution.

Clark, R.B.; Gallman, P.G.; Slotwinski, A.R. [Coleman Research Corp., Springfield, VA (United States); Wagner, K.; Weaver, S.; Xu, Jieping [Colorado Univ., Boulder, CO (United States)

1996-12-31

134

A novel backpackable ice-penetrating radar system  

NASA Astrophysics Data System (ADS)

We have developed a novel ice-penetrating radar system that can be carried on a backpack. Including batteries for a 3 hour continuous measurement, the total weight is 13 kg. In addition, it operates reliably down to -25°C, has a low power consumption of 24 W, and is semi-waterproof. The system has a built-in-one controller with a high-brightness display for reading data quickly, a receiver with 12-bit digitizing, and a 1 kV pulse transmitter in which the pulse amplitude varies by <0.2%. Optical communications between components provides low-noise data acquisition and allows synchronizing of the pulse transmission with sampling. Measurements with the system revealed the 300 m deep bed topography of a temperate valley glacier in the late ablation season.

Matsuoka, Kenichi; Saito, Ryoji; Naruse, Renji

135

Adaptive network fuzzy inference system used in interference cancellation of radar seeker  

Microsoft Academic Search

The method of adaptive network fuzzy inference system (ANFIS) applied to the interference cancellation system of radar seeker was described in this paper. When the antiaircraft missile, which adopts the pulse Doppler radar seeker, attacks the low altitude target in the down-looking mode, the seeker of missile will receive strong ground clutter. As we all know the ground clutter will

Xiang Li

2010-01-01

136

The EDOP Radar System on the High-Altitude NASA ER2 Aircraft  

Microsoft Academic Search

The NASA ER-2 high-altitude ( 20 km) aircraft that emulates a satellite view of precipitation systems carries a variety of passive and active ( lidar ) remote sensing instruments. A new Doppler weather radar system at X band ( 9.6 GHz ) called the ER-2 Doppler radar ( EDOP ) has been developed and flown on the ER-2 aircraft. EDOP

Gerald M. Heymsfield; Steven W. Bidwell; I. Jeff Caylor; Syed Ameen; Shaun Nicholson; Wayne Boncyk; Lee Miller; Doug Vandemark; Paul E. Racette; Louis R. Dod

1996-01-01

137

Algorithms of processing of radar images in radio vision systems of the car  

Microsoft Academic Search

In the report results of researches of algorithms of secondary processing of radar images (RI) in radiovision system of automobile (ARVS) are presented. ARVS is panoramic radar of the forward review with frequency modulation (FM) of a probing signal of MM wavelength. By development of algorithms following features of RI formation are considered: the sizes of the image, system of

Andrey Ananenkov; Anton Konovaltsev; Vladimir Nujdin; Vladimir Rastorguev; Pavel Sokolov

2009-01-01

138

Goldstone Solar System Radar Observatory: Earth-Based Planetary Mission Support and Unique Science Results  

Microsoft Academic Search

The Goldstone Solar System Radar (GSSR) facility is the only fully steerable radar in the world for high-resolution ranging and imaging of planetary and small-body targets. These observations provide information on surface characteristics, orbits, rotations, and polar ices for a wide variety of solar system objects. The resulting data are used not just for scientific studies of these objects, but

Martin A. Slade; Lance A. M. Benner; Arnold Silva

2011-01-01

139

Particle Cloud Detection Using Coherent Laser Radar Systems Step One  

NASA Astrophysics Data System (ADS)

Biological and chemical agents are spread out in the atmosphere in the form of particle clouds. Hence, a method to detect and localize such clouds remotely is desired. The authors report some initial experiments performed with a recently developed coherent laser radar (CLR) system wherein the results direct their future work. The CLR was used to detect particles in motion at a distance of about 25 m in a laboratory environment. These initial tests have revealed that particles are detectable by the use of a CLR and that their velocity distribution can be measured. In coming studies the authors are going to use particles with known size distribution and measure the concentration of the generated clouds/particle streams. The detection capability of the CLR system will then be determined as a function of distance and particle cloud characteristics. The goal will be to describe the conditions under which the CLR can perform as a detector of various types of clouds.

Kullander, F.; Carlsson, T.; Letalick, D.; Lindgren, M.

2001-11-01

140

Small battery operated unattended radar sensor for security systems  

NASA Astrophysics Data System (ADS)

McQ has developed, tested, and is supplying to Unattended Ground Sensor (UGS) customers a new radar sensor. This radar sensor is designed for short range target detection and classification. The design emphasis was to have low power consumption, totally automated operation, a very high probability of detection coupled with a very low false alarm rate, be able to locate and track targets, and have a price compatible with the UGS market. The radar sensor complements traditional UGS sensors by providing solutions for scenarios that are difficult for UGS. The design of this radar sensor and the testing are presented in this paper.

Plummer, Thomas J.; Brady, Stephen; Raines, Robert

2013-06-01

141

A controlled experiment to retrieve freshwater ice characteristics from an FM-CW radar system  

Microsoft Academic Search

A controlled experiment was conducted at the Cold Region Research and Engineering Laboratory (CRREL) facilities for retrieving freshwater ice characteristics using a Frequency Modulated Continuous Wave (FM-CW) radar system. The purpose of this study is to quantify the interactions between a backscattered radar signal and ice cover characteristics such as thickness and air bubble content; and to provide a comprehensive

R. Leconte; S. Daly; Y. Gauthier; N. Yankielun; F. Bérubé; M. Bernier

2009-01-01

142

Linear and non-linear filters for clutter cancellation in radar systems  

Microsoft Academic Search

The theme of this paper is the cancellation of clutter echoes in modern coherent radar systems. The receiver operating characteristics (ROC) of the following clutter filters are compared: (a) optimum linear filter, (b) the linear filter with Chebyshev tapering, and (c) the non-linear filter which takes the minimum between the outputs of few linear filters which process the same radar

A. Farina

1997-01-01

143

Detection and classification results for an impulse radar mine detection system  

Microsoft Academic Search

At Sweden's Defence Research Establishment, FOA, a hand-held mine detection device is under development. The system is based on impulse radar technique, which due to its large band width, has shown to be an effective means to find objects buried shallow in the ground. Working with radar technique gives an obvious advantage compared to e.g., metal detectors when searching for

Anders Ericsson; Anders Gustafsson

1997-01-01

144

A traffic radar verification system based on GPS–Doppler technology  

Microsoft Academic Search

In this article, a traffic radar verification system based on the GPS–Doppler technology is described. An speedometer boarded in the target vehicle estimates its speed from the Doppler variation of the GPS satellites signals, and transmits it via radio to the police vehicle, where the radar to verify is located. In order to automate the procedure and be more effective,

Soledad Torres-Guijarro; Esteban Vázquez-Fernández; Miguel Seoane-Seoane; J. Alfonso Mondaray-Zafrilla

2010-01-01

145

Ground data system architecture for precipitation determination from space-based radar  

NASA Technical Reports Server (NTRS)

The Tropical Rain Mapping Radar (Tramar) is proposed as an attached payload as part of the Space Station Earth Observing System Program. Tramar would measure rainfall rates, rain velocity, and rain cell areal extent in the latitude band from 30 deg S to 30 deg N for use in studies of large-scale atmospheric circulation, variations of latent heating, tropical hydrologic processes, and mesoscale precipitation systems. The Tramar science requirements, radar design, and ground data system architecture are examined, including the three-dimensional scan geometry, the radar system performance parameters, the production of earth-gridded maps, and the telemetry, sensor, radiometric, and geophysical data that would be obtained by Tramar.

Hilland, Jeffrey E.

1989-01-01

146

Limits on the detection of low-Doppler targets by a High Frequency hybrid sky-surface wave radar system  

Microsoft Academic Search

A high frequency (HF) radar system comprising a skywave transmit channel and surface wave receive channel is studied. Simple analytic expressions for the resolution of this radar system are determined by considering the spreading of radar signals in Doppler and angle during the ionospheric propagation. The detection of ocean surface targets within the patch of ocean surface illuminated by the

Ryan J. Riddolls

2008-01-01

147

A system for the real-time display of radar and video images of targets  

NASA Technical Reports Server (NTRS)

Described here is a software and hardware system for the real-time display of radar and video images for use in a measurement range. The main purpose is to give the reader a clear idea of the software and hardware design and its functions. This system is designed around a Tektronix XD88-30 graphics workstation, used to display radar images superimposed on video images of the actual target. The system's purpose is to provide a platform for tha analysis and documentation of radar images and their associated targets in a menu-driven, user oriented environment.

Allen, W. W.; Burnside, W. D.

1990-01-01

148

Comparison of lightning observations from the KSC LDAR system with radar observations from the NCAR CP-2 radar  

NASA Technical Reports Server (NTRS)

This grant supported observations of thunderstorms at Kennedy Space Center during the summer of 1995. In particular, we obtained detailed observations of lightning-producing storms over KSC with the CP2 radar of the National Center for Atmospheric Research (NCAR), for the purpose of comparing these with observations from KSC's Lightning Detection and Ranging (LDAR) system. The NCAR radar was a special purpose dual-polarization system for studying the development of precipitation in storms and was at KSC for another project, the Small Cumulus Microphysics Study - SCMS. We used the radar on a non-interference basis to obtain the desired observations. In addition we recorded the electrostatic field change of the lightning discharges at two locations. Subsequent to the field observational period we compared the LDAR lightning observations with the storm structure as indicated by the radar. The results obtained to date are summarized briefly as follows: (1) The initial lightning sequence in a small developing storm was observed to occur in a region of the storm where supercooled raindrops had frozen within the previous few minutes. This is consistent with the idea that the storm electrification is produced by interactions between ice particles. (2) The lightning discharges tended to avoid regions of supercooled liquid raindrops, possibly indicating that corona from the drops reduces any electrification in the vicinity of the drops. (3) 'Bilevel' lightning discharges within storms have been confirmed to be between the level of negative charge at mid-levels in the storm and the upper storm level. This is consistent with and expands upon our understanding that storms have a basic dipolar charge structure. (4) The upward channels of the intracloud lightning discharges are often aligned with shafts of strong precipitation, and often begin just above the upper extent of 40 dBZ reflectivity in the precipitation shaft. This is consistent with a precipitation-based mechanism of electrification.

Krehbiel, Paul; Rison, William

1996-01-01

149

Performance of the NASA Airborne Radar with the Windshear Database for Forward-Looking Systems  

NASA Technical Reports Server (NTRS)

This document describes the simulation approach used to test the performance of the NASA airborne windshear radar. An explanation of the actual radar hardware and processing algorithms provides an understanding of the parameters used in the simulation program. This report also contains a brief overview of the NASA airborne windshear radar experimental flight test results. A description of the radar simulation program shows the capabilities of the program and the techniques used for certification evaluation. Simulation of the NASA radar is comprised of three steps. First, the choice of the ground clutter data must be made. The ground clutter is the return from objects in or nearby an airport facility. The choice of the ground clutter also dictates the aircraft flight path since ground clutter is gathered while in flight. The second step is the choice of the radar parameters and the running of the simulation program which properly combines the ground clutter data with simulated windshear weather data. The simulated windshear weather data is comprised of a number of Terminal Area Simulation System (TASS) model results. The final step is the comparison of the radar simulation results to the known windshear data base. The final evaluation of the radar simulation is based on the ability to detect hazardous windshear with the aircraft at a safe distance while at the same time not displaying false alerts.

Switzer, George F.; Britt, Charles L.

1996-01-01

150

Guided radar system for arc detection: Initial results at DIIID  

NASA Astrophysics Data System (ADS)

A guided radar arc detection and localization system has been designed, fabricated, installed in the feed line to one of the resonant loops on the 285/300 FW antenna, and successfully tested during vacuum conditioning. The system injects a train of binary phase-modulated pulses at a carrier frequency of 25 MHz up-shifted to around 450MHz into the main high power transmission line connected to the antenna through a septate coupler and a circulator. The pulses are reflected by arcs, and the time delay provides the distance to the arc. The reflected signals are analyzed in real time, with a time response sufficient to provide active arc detection as well as localization. RF pulses have been injected into the antenna at a power level of up to 650kW. The arc location was varied by either puffing gas into the vacuum vessel, in which case arcs always occurred in the antenna, or injecting RF without a gas puff, in which case the arcs almost always occurred in the transmission line feeding the antenna. The localization obtained during these initial tests had a relatively low resolution of about 2 m, but arcs occurring inside or outside the antenna could clearly be differentiated and corresponded with the expected location. The septate coupler proved fully compatible with the antenna feed and matching network and improved performance significantly in comparison to the use of directional couplers.

Salvador, S. M.; Maggiora, R.; Goulding, R. H.; Moore, J. A.; Pinsker, R. I.; Nagy, A.

2014-02-01

151

RADAR Based Collision Avoidance for Unmanned Aircraft Systems  

NASA Astrophysics Data System (ADS)

Unmanned Aircraft Systems (UAS) have become increasingly prevalent and will represent an increasing percentage of all aviation. These unmanned aircraft are available in a wide range of sizes and capabilities and can be used for a multitude of civilian and military applications. However, as the number of UAS increases so does the risk of mid-air collisions involving unmanned aircraft. This dissertation aims to present one possible solution for addressing the mid-air collision problem in addition to increasing the levels of autonomy of UAS beyond waypoint navigation to include preemptive sensor-based collision avoidance. The presented research goes beyond the current state of the art by demonstrating the feasibility and providing an example of a scalable, self-contained, RADAR-based, collision avoidance system. The technology described herein can be made suitable for use on a miniature (Maximum Takeoff Weight < 10kg) UAS platform. This is of paramount importance as the miniature UAS field has the lowest barriers to entry (acquisition and operating costs) and consequently represents the most rapidly increasing class of UAS.

Moses, Allistair A.

152

Ultra-Wideband OFDM Radar and Communication System.  

E-print Network

??This paper examines the possibility of a dual use radar and communication systembased on ultra-wideband orthogonal frequency division multiplexed (OFDM)waveforms. Theory for utilizing OFDM as… (more)

Schuerger, Jonathan Paul

2009-01-01

153

Earth resources shuttle imaging radar. [systems analysis and design analysis of pulse radar for earth resources information system  

NASA Technical Reports Server (NTRS)

A report is presented on a preliminary design of a Synthetic Array Radar (SAR) intended for experimental use with the space shuttle program. The radar is called Earth Resources Shuttle Imaging Radar (ERSIR). Its primary purpose is to determine the usefulness of SAR in monitoring and managing earth resources. The design of the ERSIR, along with tradeoffs made during its evolution is discussed. The ERSIR consists of a flight sensor for collecting the raw radar data and a ground sensor used both for reducing these radar data to images and for extracting earth resources information from the data. The flight sensor consists of two high powered coherent, pulse radars, one that operates at L and the other at X-band. Radar data, recorded on tape can be either transmitted via a digital data link to a ground terminal or the tape can be delivered to the ground station after the shuttle lands. A description of data processing equipment and display devices is given.

1975-01-01

154

Ionospheric and auroral clutter models for HF surface wave and over-the-horizon radar systems  

NASA Astrophysics Data System (ADS)

The detection performance of high frequency surface wave radar (HFSWR) and high frequency over-the-horizon radar (OTHR) systems is heavily influenced by the presence of radar clutter. In HFSWR systems, the clutter has its origins in vertical-incidence ionospheric reflections, whereas in OTHR systems, the origin is Bragg backscatter from plasma structures in the auroral zone. This paper models the spreading of the radar clutter signal in the Doppler and angle-of-arrival domains that arises from forward-scattering effects as the radar pulse propagates through regions of ionospheric plasma irregularities. The models use a geometric optics approach to determine the power spectrum of the radar signal phase. This power spectrum is then used to simulate three-dimensional space-time-range radar data cubes. The accuracy of the models is tested by comparing the simulated data to measured data cubes. As an application, the data are then used to evaluate the performance of the newly developed fast fully adaptive (FFA) space-time adaptive processing (STAP) scheme to improve the extraction of target echoes from a clutter background.

Ravan, M.; Riddolls, R. J.; Adve, R. S.

2012-01-01

155

RADAR: An In-Building RF-based User Location and Tracking System  

Microsoft Academic Search

The proliferation of mobile computing devices and local-area wireless networks has fostered a growing interest in location-aware systems and services. In this paper we present RADAR, a radio-frequency (RF) based system for locating and tracking users inside buildings. RADAR operates by recording and processing signal strength information at multiple base stations positioned to provide overlapping coverage in the area of

Paramvir Bahl; Venkata N. Padmanabhan

2000-01-01

156

Laser radar  

Microsoft Academic Search

The general theory of laser tracking and ranging and the principles governing the design of laser radar systems are examined. Major problems related to optimum reception of laser radar signals and parameter measurement are analyzed from the standpoint of the theory of statistical solutions. Attention is given to methods for processing trajectory measurements and various methods for obtaining noncoordinate information,

I. N. Matveev; V. V. Protopopov; I. N. Troitskii; N. D. Ustinov

1984-01-01

157

Sea Clutter Reduction and Target Enhancement by Neural Networks in a Marine Radar System  

PubMed Central

The presence of sea clutter in marine radar signals is sometimes not desired. So, efficient radar signal processing techniques are needed to reduce it. In this way, nonlinear signal processing techniques based on neural networks (NNs) are used in the proposed clutter reduction system. The developed experiments show promising results characterized by different subjective (visual analysis of the processed radar images) and objective (clutter reduction, target enhancement and signal-to-clutter ratio improvement) criteria. Moreover, a deep study of the NN structure is done, where the low computational cost and the high processing speed of the proposed NN structure are emphasized. PMID:22573993

Vicen-Bueno, Raul; Carrasco-Alvarez, Ruben; Rosa-Zurera, Manuel; Nieto-Borge, Jose Carlos

2009-01-01

158

A Radar Guided Vision System for Vehicle Validation and Vehicle Motion Characterization  

Microsoft Academic Search

This paper describes a radar-guided monocular vision system that detects, validates, and tracks the preceding vehicle and thus predicts its lane-change intentions. A vision-based lane tracking process is developed to create a stable motion model in order to map the radar targets to image coordinates and consequently generate the region of interest (ROI) to search for a potential preceding vehicle.

Yi Tan; Feng Han; F. Ibrahim

2007-01-01

159

Radar electronic warfare  

Microsoft Academic Search

An overview of radar and electronic warfare is given. Definitions, common terms, and principles of radar and electronic warfare, and simple analyses of interactions between radar systems and electronic countermeasures (ECM) are presented. Electronic counter-countermeasure and electronic support measures are discussed. Background material in mathematics, electromagnetics, and probability necessary for an understanding of radar and electronic warfare is given and

August Golden Jr.

1987-01-01

160

Radar cross section  

Microsoft Academic Search

The technological evolution in signal processing that has been made in last decades led to improvements in radar performances. Increasing the radar range by improving its sensitivity has been made by the designers of aircraft and other military systems to try to decrease the radar cross section of these types of equipment. The radar cross section is a matter of

L. Nicolaescu; Teofil Oroian

2001-01-01

161

High-resolution imaging using a wideband MIMO radar system with two distributed arrays.  

PubMed

Imaging a fast maneuvering target has been an active research area in past decades. Usually, an array antenna with multiple elements is implemented to avoid the motion compensations involved in the inverse synthetic aperture radar (ISAR) imaging. Nevertheless, there is a price dilemma due to the high level of hardware complexity compared to complex algorithm implemented in the ISAR imaging system with only one antenna. In this paper, a wideband multiple-input multiple-output (MIMO) radar system with two distributed arrays is proposed to reduce the hardware complexity of the system. Furthermore, the system model, the equivalent array production method and the imaging procedure are presented. As compared with the classical real aperture radar (RAR) imaging system, there is a very important contribution in our method that the lower hardware complexity can be involved in the imaging system since many additive virtual array elements can be obtained. Numerical simulations are provided for testing our system and imaging method. PMID:20051345

Wang, Dang-wei; Ma, Xiao-yan; Chen, A-Lei; Su, Yi

2010-05-01

162

Sea Wind Power Energy Evaluation by HF Radar System  

Microsoft Academic Search

This paper presents a remote sensing method for wind energy measurement and evaluation on sea surface, which can be used for the investigation of wind farm. It provides a valid proof for building wind plants or monitoring wind farms on the sea surface. The wind speed and direction can be derived from radar echo spectrum as well as wind profile,

Wei Shen; Biyang Wen

2009-01-01

163

Radar seeker based autonomous navigation update system using topography feature matching techniques  

NASA Astrophysics Data System (ADS)

The discussed navigation update system was designed for an unmanned platform with fire and forget capability. It meets the requirement due to fully autonomous operation. The system concept will be characterized by complementary use of the radar seeker for target identification as well as for navigation function. The system works in the navigation mode during preprogrammable phases where the primary target identification function is not active or in parallel processing. The dual function radar seeker system navigates the drone during the midcourse and terminal phases of the mission. Its high resolution due to range measurement and doppler beam sharpening in context with its radar reflectivity sensing capability are the basis for topography referenced navigation computation. The detected height jumps (coming from terrain elevation and cultural objects) and radar reflectivity features will be matched together with topography referenced features. The database comprises elevation data and selected radar reflectivity features that are robust against seasonal influences. The operational benefits of the discussed system are as follows: (1) the improved navigation performance with high probability of position fixing, even over flat terrain; (2) the operation within higher altitudes; and (3) bad weather capability. The developed software modules were verified with captive flight test data running in a hardware-in-the-loop simulation.

Lerche, H. D.; Tumbreagel, F.

1992-11-01

164

Synthetic Aperture Radar Processing by a Multiple Scale Neural System for Boundary and Surface  

E-print Network

Supported in part by the Air Force Office of Scientific Reserach (AFOSR F49620­92­J­ 0499), the AdvancedSynthetic Aperture Radar Processing by a Multiple Scale Neural System for Boundary and Surface Systems and Center for Adaptive Systems Boston University 111 Cummington Street, Boston, MA 02215 4

Grossberg, Stephen

165

Investigation of the performance of a coherent array detection system for laser communications and radar  

Microsoft Academic Search

Since the atmosphere is the transmission channel for both laser communications and laser radar systems, both systems suffer the same detection problems-turbulence-induced signal fluctuations and fade. The objective of this dissertation is to demonstrate theoretically and experimentally a coherent array detection system which can mitigate effectively the signal fluctuations and fade due to the atmospheric turbulence for both applications. A

Jing Xu

1998-01-01

166

Image Reconstruction Algorithms for UWB Pulse Radar Systems Toru SATOa)  

E-print Network

deformation model 2 2 (x, y) (x, y) = 0 (x, y) 2 (x, y) 4. Synthetic Aperture Radar SAR [4] [5], [6] Ground UWB · · FBTS SEABED 1 grid model boundary points model 3 1 Table 1 Characteristics of parametric and a non- parametric algorithms. Grid Model Boundary Points Model 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7

Sato, Toru

167

Space-based radar array system simulation and validation  

NASA Astrophysics Data System (ADS)

The simulation theory and software implementation for a space-based radar RF lens are described. Infinite array theory and moment methods are used to simulate the mutual coupling among the wire radiators on each lens array face, 'feedback' coupling from the nonilluminated array to the illuminated array, active progressively phased modules interconnecting the arrays, and arbitrarily shaped thin wire radiating elements. Edge effects are accounted for by iterative techniques. Active impedances, element currents, and power gain patterns are computed.

Schuman, H. K.; Pflug, D. R.; Thompson, L. D.

1980-09-01

168

Radar applications  

NASA Astrophysics Data System (ADS)

Papers are presented on air-traffic control radar, surveillance radar, missile guidance radar, and high-performance tactical three-dimensional radar. Also considered are the airborne early warning radar, the Foxhunter airborne intercept radar, and environmental remote sensing. Other topics include spaceborne SARs, the Pioneer Orbiter radar, and a bistatic pulse-Doppler intruder-detection radar.

Skolnik, Merrill I.

169

Radar applications  

Microsoft Academic Search

Papers are presented on air-traffic control radar, surveillance radar, missile guidance radar, and high-performance tactical three-dimensional radar. Also considered are the airborne early warning radar, the Foxhunter airborne intercept radar, and environmental remote sensing. Other topics include spaceborne SARs, the Pioneer Orbiter radar, and a bistatic pulse-Doppler intruder-detection radar.

Merrill I. Skolnik

1988-01-01

170

Sensitivity of S- and Ka-band matched dual-wavelength radar system for detecting nonprecipitating cloud  

NASA Astrophysics Data System (ADS)

Remote detection of cloud phase in either liquid, ice or mixed form a key microphysical observation. Evolution of a cloud system and associated radiative properties depend on microphysical characteristics. Polarization radars rely on the shape of the particle to delineate the regions of liquid and ice. For specified transmitter and receiver characteristics, it is easier to detect a high concentrations of larger atmospheric particles than a low concentration of small particles. However, the radar cross-section of a given hydrometeor increases as the transmit frequency of the radar increases. Thus, in spite of a low transmit power, the sensitivity of a millimeter-wave radar might be better than high powered centimeter-wave radars. Also, ground clutter echoes and receiver system noise powers are sensitive functions of radar transmit frequency. For example, ground clutter in centimeter-wave radar sample volumes might mask non-precipitating or lightly precipitating clouds. An optimal clutter filter or signal processing technique can be used to suppress clutter masking its effects and/or enhanced weak cloud echoes that have significantly different Doppler characteristics than stationary ground targets. In practice, it is imperative to investigate the actual performance of S and Ka-band radar systems to detect small-scale, weak cloud reflectivity. This paper describes radar characteristics and the sensitivity of the new system in non-precipitating conditions. Recently, a dual-wavelength S and Ka-band radar system with matched resolution volume and sensitivity was built to remotely detect supercooled liquid droplets. The detection of liquid water content was based on the fact that the shorter of the two wavelengths is more strongly attenuated by liquid water. The radar system was deployed during the Winter Icing Storms Project 2004 (WISP04) near Boulder, Colorado to detect and estimate liquid water content. Observations by dual-wavelength radar were collected in both non-precipitating and lightly precipitating clouds.

Vivekanandan, J.; Politovich, Marcia; Rilling, Robert; Ellis, Scott; Pratte, Frank

2004-12-01

171

Radar electronic warfare  

NASA Astrophysics Data System (ADS)

An overview of radar and electronic warfare is given. Definitions, common terms, and principles of radar and electronic warfare, and simple analyses of interactions between radar systems and electronic countermeasures (ECM) are presented. Electronic counter-countermeasure and electronic support measures are discussed. Background material in mathematics, electromagnetics, and probability necessary for an understanding of radar and electronic warfare is given and radar tracking models are examined. The effects of various ECM emissions on radar systems are analyzed, including discussion of active ECM and angle scanning systems, angle measurement in monopulse, and automatic gain control.

Golden, August, Jr.

172

Radar-Derived Shape Model of Near-Earth Binary Asteroid System (285263) 1998 QE2  

NASA Astrophysics Data System (ADS)

We report on shape modeling of binary asteroid 1998 QE2, a 3.2-km asteroid with a 800-m moon. We observed this asteroid with both Arecibo Observatory planetary radar (2380 MHz, 12.6 cm) and Goldstone Solar System Radar (8560 MHz, 3.5 cm) between May 31-Jun 9, 2013. The close approach on May 31, 2013 (0.039 au) presented an outstanding opportunity for radar delay-Doppler imaging with resolutions as fine as 7.5 m of both objects. The extensive radar dataset was used for shape modeling of both components. Our SHAPE 3D modeling software (Hudson, 1993 and Magri et al., 2007) uses a constrained, weighted least-squares minimization procedure to invert radar delay-Doppler images.The rotation rate of the primary, 4.749 ± 0.002 h, was well constrained from optical lightcurves (P. Pravec, pers. comm.) and rotates prograde as determined from radar data. The primary is roughly spheroidal, showing prominent concavities and surface features, with effective diameter 3.2 ± 0.3 km.The secondary is irregularly shaped, with an effective diameter of 800 ± 80 m and significant elongation. The radar data suggest it is tidally locked, with an orbital period of 31.31 ± 0.01 h hours and a semi-major orbital axis of 6.2 ± 0.1 km. The orbit is approximately circular (e < 0.01), which is typical of most near-Earth asteroid binary system orbits. We estimate a preliminary density for the primary of 0.7 ± 0.2 g/cm^3. The low density is consistent with a "rubble pile" structure.

Springmann, Alessondra; Taylor, Patrick A.; Nolan, Michael C.; Howell, Ellen S.; Brozovi?, Marina; Benner, Lance A.; Giorgini, Jon D.; Busch, Michael W.; Margot, Jean-Luc; Lee, Clement; Jao, Joseph S.; Lauretta, Dante S.

2014-11-01

173

Using HF Surface Wave Radar and the Ship Automatic Identification System (AIS) to Monitor Coastal Vessels  

Microsoft Academic Search

We compare the ship detection capabilities of the automatic identification system AIS (installed on some ships) and coastal, surface wave HF radars, showing how to use both systems together to enhance ship detection performance in coastal regions. Practical reasons to want better real-time awareness of the location, velocity and type of vessels along coasts include vessel safety, protection of the

John F. Vesecky; Kenneth E. Laws; Jeffery D. Paduan

2009-01-01

174

Support of imaging radar for the shuttle system and subsystem definition study, phase 2  

NASA Technical Reports Server (NTRS)

An orbital microwave imaging radar system suggested for use in conjunction with the space shuttle is presented. Several applications of the system are described, including agriculture, meteorology, terrain analysis, various types of mapping, petroleum and mineral exploration, oil spill detection and sea and lake ice monitoring. The design criteria, which are based on the requirements of the above applications, are discussed.

1974-01-01

175

X-band Radar System for Detecting Heart and Respiration Rates  

E-print Network

X-band Radar System for Detecting Heart and Respiration Rates Jee-Hoon Lee, Yun-Taek Im, and Seong and heart rates with the periodic movement of skin and muscle near the heart. Keywords-heart rate; X system to detect heart and respiration rates of human 10m away from antenna using a high gain array

Park, Seong-Ook

176

Intelligent system for non-destructive evaluation of historic walls using Ground-Penetrating Radar  

Microsoft Academic Search

This paper presents a novel system evaluation of ashlar masonry walls inspec Penetrating Radar (GPR). The system inclu processing of the GPR signal: elimination o from the backscattered signals; depth reso automatic gain control for visualization generation of B-Scans (radargrams) of the in wall. Inhomogeneities in the structure of the from the B-Scans. Several experiments we models of historic ashlar

Gonzalo Safont; Addisson Salazar; Jorge Gosalbez; Luis Vergara

2010-01-01

177

Primary propulsion of electrothermal, ion, and chemical systems for space-based radar orbit transfer  

NASA Technical Reports Server (NTRS)

An orbit transfer mission concept has been studied for a Space-Based Radar (SBR) where 40 kW required for radar operation is assumed available for orbit transfer propulsion. Arcjet, pulsed electrothermal (PET), ion, and storable chemical systems are considered for the primary propulsion. Transferring two SBR per shuttle flight to 1112 km/60 deg using eiectrical propulsion systems offers an increased payload at the expense of increased trip time, up to 2000 kg each, which may be critical for survivability. Trade offs between payload mass, transfer time, launch site, inclination, and height of parking orbits are presented.

Wang, S.-Y.; Staiger, P. J.

1985-01-01

178

Statistical evaluation of a radar rainfall system for sewer system management  

NASA Astrophysics Data System (ADS)

Urban areas are faced with mounting demands for managing waste and stormwater for a cleaner environment. Rainfall information is a critical component in efficient management of urban drainage systems. A major water quality impact affecting receiving waterbodies is the discharge of untreated waste and stormwater during precipitation, termed wet weather flow. Elimination or reduction of wet weather flow in metropolitan sewer districts is a major goal of environmental protection agencies and often requires considerable capital improvements. Design of these improvements requires accurate rainfall data in conjunction with monitored wastewater flow data. Characterizing the hydrologic/hydraulic performance of the sewer using distant rain gauges can cause oversizing and wasted expenditures. Advanced technology has improved our ability to measure accurately rainfall over large areas. Weather radar, when combined with rain gauge measurements, provides detailed information concerning rainfall intensities over specific watersheds. Knowing how much rain fell over contributing areas during specific periods aids in characterizing inflow and infiltration to sanitary and combined sewers, calibration of sewer system models, and in operation of predictive real-time control measures. Described herein is the design of a system for managing rainfall information for sewer system management, along with statistical analysis of 60 events from a large metropolitan sewer district. Analysis of the lower quartile rainfall events indicates that the expected average difference is 25.61%. Upper quartile rainfall events have an expected average difference of 17.25%. Rain gauge and radar accumulations are compared and evaluated in relation to specific needs of an urban application. Overall, the events analyzed agree to within ± 8% based on the median average difference between gauge and radar.

Vieux, B. E.; Vieux, J. E.

2005-09-01

179

SAR (Synthetic Aperture Radar). Earth observing system. Volume 2F: Instrument panel report  

NASA Technical Reports Server (NTRS)

The scientific and engineering requirements for the Earth Observing System (EOS) imaging radar are provided. The radar is based on Shuttle Imaging Radar-C (SIR-C), and would include three frequencies: 1.25 GHz, 5.3 GHz, and 9.6 GHz; selectable polarizations for both transmit and receive channels; and selectable incidence angles from 15 to 55 deg. There would be three main viewing modes: a local high-resolution mode with typically 25 m resolution and 50 km swath width; a regional mapping mode with 100 m resolution and up to 200 km swath width; and a global mapping mode with typically 500 m resolution and up to 700 km swath width. The last mode allows global coverage in three days. The EOS SAR will be the first orbital imaging radar to provide multifrequency, multipolarization, multiple incidence angle observations of the entire Earth. Combined with Canadian and Japanese satellites, continuous radar observation capability will be possible. Major applications in the areas of glaciology, hydrology, vegetation science, oceanography, geology, and data and information systems are described.

1987-01-01

180

Clutter cancellation techniques for use in a space-based radar system  

NASA Astrophysics Data System (ADS)

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent on the clutter cancellation technique employed. To thoroughly understand the nature of clutter so as to efficiently and effectively design and develop clutter cancellation techniques, fundamental mathematical relationships dealing with radar signal representation, probability theory, detection and estimation theory and signal comparison techniques were established and defined. Since the implementation of the mathematical expressions which describe clutter and clutter cancellation techniques are accomplished digitally, digital signal representation and digital filter characterization via FFt's were also established and defined. Drawing upon the established mathematical principles, as well as temporal probability models, spectral models and average backscatter coefficient models, clutter was described. Capitalizing on the different spectral characteristics between clutter and targets, three representative Doppler cancellation schemes were developed. The three schemes were delay line cancelers, Doppler filter banks and multiple look systems.

Devenuto, J.

1983-12-01

181

(abstract) Asteroids and Comets: Future Imaging Opportunities with Earth-Based Radar Systems  

NASA Technical Reports Server (NTRS)

Major improvements currently underway to the Arecibo 305 m antenna and 13 cm wavelength radar system will currently increase the radar system's sensitivity by a factor of about 20. Recent upgrades to the Goldstone 3.5 cm wavelength radar system have also improved its sensitivity. While the Arecibo system will have significantly greater sensitivity than Goldstone, the Arecibo antenna's limited declination coverage of -2(deg) to +38(deg) means that the Goldstone system will be important for the investigation of near-Earth objects with declinations outside this range. Over one hundred mainbelt and near-Earth asteroids per year will be observable with the new Arecibo system, and there will be a number of good imaging opportunities each year. While only a few imaging opportunities are predicted for comets over the next 10 years, the system will be able to respond to unexpected cometary opportunities. We are currently investigating the applicability of VLBI techniques to the direct synthesis of images of asteroids and comets illuminated by a radar signal.

Campbell, D. B.; Black, G. J.; Ostro, S. J.

1994-01-01

182

Validation of the radiation pattern of the Middle Atmosphere Alomar Radar System (MAARSY)  

NASA Astrophysics Data System (ADS)

In 2009/2010 the Leibniz-Institute of Atmospheric Physics (IAP) installed a new powerful VHF radar on the island Andøya in Northern Norway (69.30° N, 16.04° E). The Middle Atmosphere Alomar Radar System (MAARSY) allows studies with high spatial and temporal resolution in the troposphere/lower stratosphere and in the mesosphere/lower thermosphere of the Arctic atmosphere. The monostatic radar is operated at 53.5 MHz with an active phased array antenna consisting of 433 Yagi antennas. Each individual antenna is connected to its own transceiver with independent phase control and a scalable power output of up to 2 kW, which implies high flexibility of beam forming and beam steering. During the design phase of MAARSY several model studies have been carried out in order to estimate the radiation pattern for various combinations of beam forming and steering. However, parameters like mutual coupling, active impedance and ground parameters have an impact on the radiation pattern, but can hardly be measured. Hence, experiments need to be designed to verify the model results. For this purpose, the radar has occasionally been used in passive mode, monitoring the noise power received from both distinct cosmic noise sources like e.g. Cassiopeia A and Cygnus A, and the diffuse cosmic background noise. The analysis of the collected dataset enables us to verify beam forming and steering attempts. These results document the current status of the radar during its development and provide valuable information for further improvement.

Renkwitz, T.; Singer, W.; Latteck, R.; Stober, G.; Rapp, M.

2012-09-01

183

Considerations for a Radar System to Detect an Ocean Underneath the Icy Shell of Europa  

NASA Technical Reports Server (NTRS)

The detection of an ocean underneath Europa is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. An orbiting surface penetrating radar has the potential of providing that measurement thus yielding information regarding the possibility of life support on Europa. Radars in the MHz range have successfully monitored the kilometer-deep ice shelves of Greenland and Antarctica, including the detection of Lake Vostok (and others) below an ice sheet thickness of about 4 km. The performance of a radar system orbiting Europa will be subject to several potential complications and unknowns. Besides ionospheric dispersion and the actual depth of the ocean, which is estimated between 2 and 30 km, major unknowns affecting radar performance are the temperature profile, the amount of salt and other impurities within the ice crust as well as the surface roughness. These impurities can in part be produced at the highly irradiated surface by magnetospheric interactions and transported downward into the ice crust by geologic processes. The ionospheric interference must also be modeled from effects of these interactions on production of the thin neutral atmosphere and subsequent ionization of the neutrals. We investigated these uncertainties through radar simulations using different surface and ice characteristics over a frequency range from 10 to 50 MHz. The talk will present results from these simulations discussing potential limitations.

Markus, Thorsten; Gogineni, Prasad; Green, James; Cooper, John; Fung, Shing; Taylor, William; Benson, Robert; Reinisch, Bodo; Song, Paul

2004-01-01

184

Radar detection of NEA 33342 (1998 WT24) with Evpatoria => Medicina system at 6 cm  

NASA Astrophysics Data System (ADS)

We present the first radar detection of near-Earth asteroid 1998 WT24 that was performed with the bistatic system Evpatoria ? Medicina operating at 6 cm wavelength during WT24 close approaching to Earth at a distance of 0.0125 AU. Radar echo from WT24 was detected during both observational days on Dec. 16, 17, 2001. The maximum value of signal to noise level ratio was about 0.4 for filter, matched with echo bandwidth, which results in OC radar cross section of 0.02 km2. Doppler trend of spectrum center doesn't exceed 0.44 mHz/sec, the echo spectrum bandwidth varies from 6.2 to 6.7 Hz and the WT24's pole-on breadth is ~0.41 km, the estimation of radar albedo is ~0.1. Of most interest is the measurements result giving near-unity circular polarization ratio. Such combination of low radar albedo and near-unity circular polarization ratio may be interpreted as a property of comet-like surface.

Zaitsev, Alexander L.; di Martino, Mario; Konovalenko, Alexander A.; Montebugnoli, Stelio; Ignatov, Sergei P.; Kolyuka, Yuri F.; Nabatov, Alexander S.; Falkovich, Igor S.; Gavrik, Anatoly L.; Gavrik, Yuri A.; Bortolotti, Claudio; Cattani, Alessandro; Maccaferri, Andrea; Maccaferri, Giuseppe; Roma, Mauro; Delbo, Marco; Saba, Laura; Afanas'eva, Tatiana; Gridshina, Tatiana; Righini, Simona

2002-11-01

185

Wind fluctuations near a cold vortex-tropopause funnel system observed by the MU radar  

NASA Astrophysics Data System (ADS)

Vertical and temporal variations of three-dimensional wind velocity associated with an upper-tropospheric cold vortex-tropopause funnel system were observed by an MST radar in Japan (the MU radar). Marked changes of vertical velocity and horizontal wind direction were found between the inside and outside of the cold vortex. The vertical velocity activity outside the vortex was asymmetric; it was most active in a sector before the vortex. Unsaturated internal gravity waves in their generation stage contribute predominantly to the vertical velocity activity, suggesting that tropospheric occluded cyclones may be a possible source of middle-atmospheric gravity waves through the geostrophic adjustment process.

Fukao, Shoichiro; Yamanaka, Manabu D.; Matsumoto, Hiromasa; Sato, Toru; Tsuda, Toshitaka; Kato, Susumu

1989-06-01

186

Horizontally resolved structures of polar mesospheric echoes obtained with the Middle Atmosphere Alomar Radar System  

NASA Astrophysics Data System (ADS)

Polar Mesosphere Summer Echoes have been observed in Andenes/Norway (69°N, 16°E) for more than 18 years using the Alomar SOUSY and the ALWIN VHF radars. In 2011 the Leibniz-Institute of Atmospheric Physics in Kühlungsborn completed the installation of the Middle Atmosphere Alomar Radar System ({MAARSY}). The new radar is designed for atmospheric studies from the troposphere up to the lower thermosphere, especially for the investigation of horizontal structures of polar mesospheric echoes. The system is composed of an active phased antenna consisting of 433 array elements and an identical number of transceiver modules individually controllable in frequency, phase, and output power on a pulse-to-pulse basis. This arrangement allows very high flexibility of beam forming and beam steering with a symmetric 3.6° small radar beam and arbitrary beam pointing directions down to 30° off-zenith. The monitoring of polar mesosphere echoes using a vertical pointed radar beam has been continued already during the construction period of MAARSY in order to complete the long term data base available for Andenes. Additionally first multi-beam scanning experiments using up to 97 beams quasi-simultaneously in the mesosphere have been carried out during several campaigns starting in summer 2010. Sophisticated wind analysis methods such as an extended velocity azimuth display have been applied to retrieve additional parameters from the wind field, e.g. horizontal divergence, vertical velocity, stretching and shearing deformation. The results provide a first insight into the strong horizontal variability of scattering structures occurring in the polar mesosphere over Andenes during summer and winter time. The implementation of interferometric radar imaging methods offers further improvement of the horizontal and the vertical resolution.

Latteck, Ralph; Zecha, Marius; Rapp, Markus; Stober, Gunter; Singer, Werner

2012-07-01

187

Hypothesis of natural radar detection, navigation and direction finding tracking systems guiding hornets flight  

Microsoft Academic Search

The hypothesis of a natural sophisticated radar navigation system guiding hornets flight and detecting obstacles and preys is derived from the investigation of the complex spike elements arrays on their cuticle skin shown by electronic microscope pictures. The occurrence of three different lengths and disposition of the spike elements lead from analogy with antenna and radio theory and practice to

J. Gavan; J. S. Ishay

2000-01-01

188

A cooperative radar system for collision avoidance and communications between vehicles  

Microsoft Academic Search

In order to improve reliability, security on roads or exploitation of automatic guided transports, many sensors are being developed to equip vehicles. Research has been carried out at INRETS and IEMN on low cost microwave collision avoidance sensors for metro guided transports and for road vehicles. For this goal, an original radar system has been designed in ours laboratories. It

C. Tatkeu; P. Deloof; Y. Elhillali; A. Rivenq; J. M. Rouvaen

2006-01-01

189

Radar, satellite, and lightning characteristics of select mesoscale convective systems in Texas  

E-print Network

This study compares radar data from the League City, Texas WSR-88D and cloud-to-ground (CG) lightning data for a set of eight mesoscale convective systems (MCSs) which occur at various stages of development along the upper Texas Gulf Coast. Vertical...

Toracinta, Ernest Richard

2012-06-07

190

Study of a Planar Spiral Antenna Used in Ground Penetrating Radar System  

Microsoft Academic Search

A planar Archimedean-spiral antenna used in UHF ground penetrating radar system is studied. How to have an effect on frequency property for antenna by changing absorbing structures placed in reflecting cavity is analyzed. According to the analytical result, a new absorbing structure is designed and actual measurement is carried out. Finally, the azimuth pattern and radiation property for antenna is

Zhiwen Xiao; Jianguo He; Peiguo Liu

2008-01-01

191

Upgraded Doppler Rayleigh Lidar and Comparisonswith Stratospheric Radar: 1: Observations Following Initial System Modifications  

E-print Network

Upgraded Doppler Rayleigh Lidar and Comparisonswith Stratospheric Radar: 1: Observations Following-mail mikek@ee,comell.edu We prescnt lidar observations of density fluctuations in the presence of thin cloud. These observationsfollowedthe initial stage of a Doppler Rayleigh lidar system upgrade. These initial observations were made

Cho, John Y. N.

192

Space-based radar array system simulation and validation  

NASA Astrophysics Data System (ADS)

The present status of the space-based radar phased array lens simulator is discussed. Huge arrays of thin wire radiating elements on either side of a ground screen are modeled by the simulator. Also modeled are amplitude and phase adjust modules connecting radiating elements between arrays, feedline to radiator mismatch, and lens warping. A successive approximation method is employed. The first approximation is based on a plane wave expansion (infinite array) moment method especially suited to large array analysis. the first approximation results then facilitate higher approximation computations that account for effects of nonuniform periodicities (lens edge, lens section interfaces, failed modules, etc.). The programming to date is discussed via flow diagrams. An improved theory is presented in a consolidated development. The use of the simulator is illustrated by computing active impedances and radiating element current distributions for infinite planar arrays of straight and 'swept back' dipoles (arms inclined with respect to the array plane) with feedline scattering taken into account.

Schuman, H. K.; Pflug, D. R.; Thompson, L. D.

1981-08-01

193

THE REGIONAL AND DIURNAL VARIABILITY OF THE VERTICAL STRUCTURE OF PRECIPITATION SYSTEMS IN AFRICA, BASED ON TRMM PRECIPITATION RADAR DATA  

E-print Network

IN AFRICA, BASED ON TRMM PRECIPITATION RADAR DATA Bart Geerts1 and Teferi Dejene University of Wyoming 1 by means of reflectivity profiles derived from the Precipitation Radar (PR) aboard the Tropical RainfallP3A.6 THE REGIONAL AND DIURNAL VARIABILITY OF THE VERTICAL STRUCTURE OF PRECIPITATION SYSTEMS

Geerts, Bart

194

Implementation and evaluation of coherent synthetic aperture radar processing for level measurements of bulk goods with an FMCW-system  

Microsoft Academic Search

In industrial process measurement instrumentation, radar systems are well established for the measurement of filling levels of liquids in tanks. Level measurements of bulk goods in silos, on the other hand, are more challenging because the material is heaped up and its surface has typically a relatively complex shape. In this paper, the application of synthetic aperture radar (SAR) reconstruction

M. Vogt; M. Gerding; T. Musch

2010-01-01

195

Data Acquisition System for Multi-Frequency Radar Flight Operations Preparation  

NASA Technical Reports Server (NTRS)

A three-channel data acquisition system was developed for the NASA Multi-Frequency Radar (MFR) system. The system is based on a commercial-off-the-shelf (COTS) industrial PC (personal computer) and two dual-channel 14-bit digital receiver cards. The decimated complex envelope representations of the three radar signals are passed to the host PC via the PCI bus, and then processed in parallel by multiple cores of the PC CPU (central processing unit). The innovation is this parallelization of the radar data processing using multiple cores of a standard COTS multi-core CPU. The data processing portion of the data acquisition software was built using autonomous program modules or threads, which can run simultaneously on different cores. A master program module calculates the optimal number of processing threads, launches them, and continually supplies each with data. The benefit of this new parallel software architecture is that COTS PCs can be used to implement increasingly complex processing algorithms on an increasing number of radar range gates and data rates. As new PCs become available with higher numbers of CPU cores, the software will automatically utilize the additional computational capacity.

Leachman, Jonathan

2010-01-01

196

Radar Observations of Convective Systems from a High-Altitude Aircraft  

NASA Technical Reports Server (NTRS)

Reflectivity data collected by the precipitation radar on board the tropical Rainfall Measuring Mission (TRMM) satellite, orbiting at 350 km altitude, are compared to reflectivity data collected nearly simultaneously by a doppler radar aboard the NASA ER-2 flying at 19-20 km altitude, i.e. above even the deepest convection. The TRMM precipitation radar is a scanning device with a ground swath width of 215 km, and has a resolution of about a4.4 km in the horizontal and 250 m in the vertical (125 m in the core swath 48 km wide). The TRMM radar has a wavelength of 217 cm (13.8 GHz) and the Nadir mirror echo below the surface is used to correct reflectivity for loss by attenuation. The ER-2 Doppler radar (EDOP) has two antennas, one pointing to the nadir, 34 degrees forward. The forward pointing beam receives both the normal and the cross-polarized echos, so the linear polarization ratio field can be monitored. EDOP has a wavelength of 3.12 cm (9.6 GHz), a vertical resolution of 37.5 m and a horizontal along-track resolution of about 100 m. The 2-D along track airflow field can be synthesized from the radial velocities of both beams, if a reflectivity-based hydrometer fall speed relation can be assumed. It is primarily the superb vertical resolution that distinguishes EDOP from other ground-based or airborne radars. Two experiments were conducted during 1998 into validate TRMM reflectivity data over convection and convectively-generated stratiform precipitation regions. The Teflun-A (TEXAS-Florida Underflight) experiment, was conducted in April and May and focused on mesoscale convective systems mainly in southeast Texas. TEFLUN-B was conducted in August-September in central Florida, in coordination with CAMEX-3 (Convection and Moisture Experiment). The latter was focused on hurricanes, especially during landfall, whereas TEFLUN-B concentrated on central; Florida convection, which is largely driven and organized by surface heating and ensuing sea breeze circulations. Both TEFLUN-A and B were amply supported by surface data, in particular a dense raingauge network, a polarization radar, wind profilers, a mobile radiosonde system, a cloud physics aircraft penetrating the overflown storms, and a network of 10 cm Doppler radars(WSR-88D). This presentation will show some preliminary comparisons between TRMM, EDOP, and WSR-88D reflectivity fields in the case of an MCS, a hurricane, and less organized convection in central Florida. A validation of TRMM reflectivity is important, because TRMM's primary objective is to estimate the rainfall climatology with 35 degrees of the equator. Rainfall is estimated from the radar reflectivity, as well from TRMM's Microwave Imager, which measures at 10.7, 19.4, 21.3, 37, and 85.5 GHz over a broader swath (78 km). While the experiments lasted about three months the cumulative period of near simultaneous observations of storms by ground-based, airborne and space borne radars is only about an hour long. Therefore the comparison is case-study-based, not climatological. We will highlight fundamental differences in the typical reflectivity profiles in stratiform regions of MCS's, Florida convection and hurricanes and will explain why Z-R relationships based on ground-based radar data for convective systems over land should be different from those for hurricanes. These catastrophically intense rainfall from hurricane Georges in Hispaniola and from Mitch in Honduras highlights the importance of accurate Z-R relationships, It will be shown that a Z-R relationship that uses the entire reflectivity profile (rather than just a 1 level) works much better in a variety of cases, making an adjustment of the constants for different precipitation system categories redundant.

Heymsfield, G.; Geerts, B.; Tian, L.

1999-01-01

197

European project RESOLUTION-local positioning systems based on novel FMCW radar  

Microsoft Academic Search

This paper gives an overview of the European (EU) project RESOLUTION (reconfigurable systems for mobile local communication and positioning). RESOLUTION aims at developing a wireless three-dimensional (3-D) local positioning system with accuracy in the centimeter regime. A novel frequency modulated continuous wave (FMCW) radar principle is employed and co-designed together with common WLAN systems operating around 5 GHz. At 140

F. Ellinger; R. Eickhoff; A. Ziroff; J. Huttner; R. Gierlich; J. Carls; G. Bock

2007-01-01

198

MMW radar enhanced vision systems: the Helicopter Autonomous Landing System (HALS) and Radar-Enhanced Vision System (REVS) are rotary and fixed wing enhanced flight vision systems that enable safe flight operations in degraded visual environments  

NASA Astrophysics Data System (ADS)

Sierra Nevada Corporation (SNC) has developed rotary and fixed wing millimeter wave radar enhanced vision systems. The Helicopter Autonomous Landing System (HALS) is a rotary-wing enhanced vision system that enables multi-ship landing, takeoff, and enroute flight in Degraded Visual Environments (DVE). HALS has been successfully flight tested in a variety of scenarios, from brown-out DVE landings, to enroute flight over mountainous terrain, to wire/cable detection during low-level flight. The Radar Enhanced Vision Systems (REVS) is a fixed-wing Enhanced Flight Vision System (EFVS) undergoing prototype development testing. Both systems are based on a fast-scanning, threedimensional 94 GHz radar that produces real-time terrain and obstacle imagery. The radar imagery is fused with synthetic imagery of the surrounding terrain to form a long-range, wide field-of-view display. A symbology overlay is added to provide aircraft state information and, for HALS, approach and landing command guidance cuing. The combination of see-through imagery and symbology provides the key information a pilot needs to perform safe flight operations in DVE conditions. This paper discusses the HALS and REVS systems and technology, presents imagery, and summarizes the recent flight test results.

Cross, Jack; Schneider, John; Cariani, Pete

2013-05-01

199

The 94 GHz Cloud Radar System on a NASA ER-2 Aircraft  

NASA Technical Reports Server (NTRS)

The 94-GHz (W-band) Cloud Radar System (CRS) has been developed and flown on a NASA ER-2 high-altitude (20 km) aircraft. The CRS is a fully coherent, polarimeteric Doppler radar that is capable of detecting clouds and precipitation from the surface up to the aircraft altitude in the lower stratosphere. The radar is especially well suited for cirrus cloud studies because of its high sensitivity and fine spatial resolution. This paper describes the CRS motivation, instrument design, specifications, calibration, and preliminary data &om NASA s Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign. The unique combination of CRS with other sensors on the ER-2 provides an unprecedented opportunity to study cloud radiative effects on the global energy budget. CRS observations are being used to improve our knowledge of atmospheric scattering and attenuation characteristics at 94 GHz, and to provide datasets for algorithm implementation and validation for the upcoming NASA CloudSat mission that will use a 94-GHz spaceborne cloud radar to provide the first direct global survey of the vertical structure of cloud systems.

Li, Lihua; Heymsfield, Gerald M.; Racette, Paul E.; Tian, Lin; Zenker, Ed

2003-01-01

200

Moving Target Parameters Estimation in Noncoherent MIMO Radar Systems  

NASA Astrophysics Data System (ADS)

The problem of estimating the parameters of a moving target in multiple-input multiple-output (MIMO) radar is considered and a new approach for estimating the moving target parameters by making use of the phase information associated with each transmit-receive path is introduced. It is required for this technique that different receive antennas have the same time reference, but no synchronization of initial phases of the receive antennas is needed and, therefore, the estimation process is non-coherent. We model the target motion within a certain processing interval as a polynomial of general order. The first three coefficients of such a polynomial correspond to the initial location, velocity, and acceleration of the target, respectively. A new maximum likelihood (ML) technique for estimating the target motion coefficients is developed. It is shown that the considered ML problem can be interpreted as the classic "overdetermined" nonlinear least-squares problem. The proposed ML estimator requires multi-dimensional search over the unknown polynomial coefficients. The Cram\\'er-Rao Bound (CRB) for the proposed parameter estimation problem is derived. The performance of the proposed estimator is validated by simulation results and is shown to achieve the CRB.

Hassanien, Aboulnasr; Vorobyov, Sergiy A.; Gershman, Alex B.

2012-05-01

201

Micropower impulse radar  

Microsoft Academic Search

Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s

S. Azevedo; T. E. McEwan

1996-01-01

202

CAMUS: an infrared, visible, and millimeter-wave radar integration system  

NASA Astrophysics Data System (ADS)

The Defense Research Establishment, Valcartier has an ongoing project on a multi-sensors system, called CAMUS (Common Aperture MUlti-Sensors). The main objective of this project is to demonstrate the concept of fusing three sensors on a single chassis. The project covers the development of the sensors' head and the processing sub-systems required for fusing the acquired data and information. The three sensors identified for this project are: a visible camera, a 3 - 5 micrometer infrared camera and a 94 GHz millimeter-wave radar. This paper describes the approach used to combine the three sensors along with the various processing schemes to merge the visible and infrared images with the radar information. The CAMUS system will present all the information gathered by the three sensors on a single display to the operator. The main application of this project is to demonstrate an advanced sight for a direct fire control system.

de Villers, Yves M.; Simard, Jean-Robert

1998-10-01

203

Rain-Mapping Radar  

NASA Technical Reports Server (NTRS)

Orbiting radar system measures rates of rainfall from 0.5 to 60 mm/h. Radar waves scattered and absorbed by rainfall to extents depending on wavelength, polarization, rate of rainfall, and distribution of sizes and shapes of raindrops. Backscattered radar signal as function of length of path through rain used to infer detailed information about rain. Accumulated radar return signals processed into global maps of monthly average rainfall for use in climatological studies.

Im, K. E.; Li, F. K.; Wilson, W. J.; Rosing, D.

1988-01-01

204

Radar systems for a polar mission, volume 3, appendices A-D, S, T  

NASA Technical Reports Server (NTRS)

Success is reported in the radar monitoring of such features of sea ice as concentration, floe size, leads and other water openings, drift, topographic features such as pressure ridges and hummocks, fractures, and a qualitative indication of age and thickness. Scatterometer measurements made north of Alaska show a good correlation with a scattering coefficient with apparent thickness as deduced from ice type analysis of stereo aerial photography. Indications are that frequencies from 9 GHz upward seem to be better for sea ice radar purposes than the information gathered at 0.4 GHz by a scatterometer. Some information indicates that 1 GHz is useful, but not as useful as higher frequencies. Either form of like-polarization can be used and it appears that cross-polarization may be more useful for thickness measurement. Resolution requirements have not been fully established, but most of the systems in use have had poorer resolution than 20 meters. The radar return from sea ice is found to be much different than that from lake ice. Methods to decrease side lobe levels of the Fresnel zone-plate processor and to decrease the memory requirements of a synthetic radar processor are discussed.

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

205

MICROPROCESSOR-BASED DATA-ACQUISITION SYSTEM FOR A BOREHOLE RADAR.  

USGS Publications Warehouse

An efficient microprocessor-based system is described that permits real-time acquisition, stacking, and digital recording of data generated by a borehole radar system. Although the system digitizes, stacks, and records independently of a computer, it is interfaced to a desktop computer for program control over system parameters such as sampling interval, number of samples, number of times the data are stacked prior to recording on nine-track tape, and for graphics display of the digitized data. The data can be transferred to the desktop computer during recording, or it can be played back from a tape at a latter time. Using the desktop computer, the operator observes results while recording data and generates hard-copy graphics in the field. Thus, the radar operator can immediately evaluate the quality of data being obtained, modify system parameters, study the radar logs before leaving the field, and rerun borehole logs if necessary. The system has proven to be reliable in the field and has increased productivity both in the field and in the laboratory.

Bradley, Jerry A.; Wright, David L.

1987-01-01

206

Phase modulating the Urbana radar  

NASA Technical Reports Server (NTRS)

The design and operation of a switched phase modulation system for the Urbana Radar System are discussed. The system is implemented and demonstrated using a simple procedure. The radar system and circuits are described and analyzed.

Herrington, L. J., Jr.; Bowhill, S. A.

1983-01-01

207

Phase locking of multiple optical fiber channels for a slow-light-enabled laser radar system.  

PubMed

Phase control is crucial to the operation of coherent beam combining systems, whether for laser radar or high-power beam combining. We have recently demonstrated a design for a multi-aperture, coherently combined, synchronized- and phased-array slow light laser radar (SLIDAR) that is capable of scanning in two dimensions with dynamic group delay compensation. Here we describe in detail the optical phase locking system used in the design. The phase locking system achieves an estimated Strehl ratio of 0.8, and signals from multiple emitting apertures are phase locked simultaneously to within ?/5 radians (1/10 wave) after propagation through 2.2 km of single-mode fiber per channel. Phase locking performance is maintained even as two independent slow light mechanisms are utilized simultaneously. PMID:23736563

Vornehm, Joseph E; Schweinsberg, Aaron; Shi, Zhimin; Gauthier, Daniel J; Boyd, Robert W

2013-06-01

208

A convenient technique for polarimetric calibration of single-antenna radar systems  

NASA Technical Reports Server (NTRS)

A practical technique for calibrating single-antenna polarimetric radar systems is introduced. This technique requires only a single calibration target such as a conducting sphere or a trihedral corner reflector to calibrate the radar system, both in amplitude and phase, for all linear polarization configurations. By using a metal sphere, which is orientation independent, error in calibration measurement is minimized while simultaneously calibrating the crosspolarization channels. The antenna system and two orthogonal channels (in free space) are modeled as a four-port passive network. Upon using the reciprocity relations for the passive network and assuming the crosscoupling terms of the antenna to be equal, the crosstalk factors of the antenna system and the transmit and receive channel imbalances can be obtained from measurement of the backscatter from a metal sphere. For an X-band radar system with crosspolarization isolation of 25 dB, comparison of values measured for a sphere and a cylinder with theoretical values shows agreement within 0.4 dB in magnitude and 5 deg in phase. An effective polarization isolation of 50 dB is achieved using this calibration technique.

Sarabandi, Kamal; Ulaby, Fawwaz T.

1990-01-01

209

Meta level tracking with multimode space-time adaptive processing of GMTI data  

Microsoft Academic Search

Ground surveillance of the battlefield provides military analysts with information that is critical to the success of a mission; the type of the information includes the enemy force structure, enemy offensive combat formation, and maneuvering events. The conventional approach uses mainly the synthetic aperture radar (SAR) and electro-optical (EO) sensors to perform detection and identification of stationary targets on the

Alex Wang; Vikram Krishnamurthy; Bhashyam Balaji

2009-01-01

210

Comparative of signal processing techniques for micro-Doppler signature extraction with automotive radar systems  

NASA Astrophysics Data System (ADS)

In recent years, the automotive industry has experienced an evolution toward more powerful driver assistance systems that provide enhanced vehicle safety. These systems typically operate in the optical and microwave regions of the electromagnetic spectrum and have demonstrated high efficiency in collision and risk avoidance. Microwave radar systems are particularly relevant due to their operational robustness under adverse weather or illumination conditions. Our objective is to study different signal processing techniques suitable for extraction of accurate micro-Doppler signatures of slow moving objects in dense urban environments. Selection of the appropriate signal processing technique is crucial for the extraction of accurate micro-Doppler signatures that will lead to better results in a radar classifier system. For this purpose, we perform simulations of typical radar detection responses in common driving situations and conduct the analysis with several signal processing algorithms, including short time Fourier Transform, continuous wavelet or Kernel based analysis methods. We take into account factors such as the relative movement between the host vehicle and the target, and the non-stationary nature of the target's movement. A comparison of results reveals that short time Fourier Transform would be the best approach for detection and tracking purposes, while the continuous wavelet would be the best suited for classification purposes.

Rodriguez-Hervas, Berta; Maile, Michael; Flores, Benjamin C.

2014-05-01

211

Simulation of airborne radar observations of precipitating systems at various frequency bands  

NASA Astrophysics Data System (ADS)

The choice of the microwave frequency is of considerable importance for precipitating system observations by airborne radar. Currently, these radars operate at X-band (f = 10 GHz), although other frequency bands, may be used jointly or not. Since the measured reflectivity Zm is f-depending, different physical information about precipitating systems could be obtained. Herein, a comparison of reflectivity fields at different frequency bands is presented. A realistic and flexible model of precipitating systems is presented and simulations of airborne radar observations are performed. Simulated reflectivity fields are degraded as/increases because of Mie effects and microwave attenuation. At S, C and X-bands, attenuation is weak and Mie effects slightly increase the backscattered signal such that they can compensate attenuation at X and Ku bands. The Ka and W-bands suffer from a strong attenuation and significant Mie effects which seriously alter Zm-fields. For a squall line, the closer convective tower hides the farther ones, which is problematic for a pilot to estimate hazard at long distance. In addition, because hail is the main meteorological hazard for civil aviation, hail-rain discrimination is discussed and clarified for convective systems. It appears that S, C, and X-bands are the best ones, but the significant size of antenna used is prohibitive. Higher frequencies are more difficult to use on civil aviation due to high ambiguities and a too strongly attenuated microwave signal.

Louf, Valentin; Pujol, Olivier; Riedi, Jérôme

2013-05-01

212

Last printed 3/16/2004 3:01 PM High-Frequency (Light) Borehole-Radar System  

E-print Network

forks (2-3) with safety lines. 18) Surface radar antenna control electronics and radiating elements computer with acquisition software, manuals, logbook and protocol sheets. 3) Backup system; zip, jaz, or CD

Barrash, Warren

213

Improving Ground Penetrating Radar Imaging in High Loss Environments by Coordinated System Development, Data Processing, Numerical Modeling, & Visualization  

SciTech Connect

Improving Ground Penetrating Radar Imaging in High Loss Environments by Coordinated System Development, Data Processing, Numerical Modeling, and Visualization Methods with Applications to Site Characterization EMSP Project 86992 Progress Report as of 9/2004.

Wright, David L.

2004-12-01

214

A study of an orbital radar mapping mission to Venus. Volume 2: Configuration comparisons and systems evaluation  

NASA Technical Reports Server (NTRS)

Configuration comparisons and systems evaluation for the orbital radar mapping mission of the planet Venus are discussed. Designs are recommended which best satisfy the science objectives of the Venus radar mapping concept. Attention is given to the interaction and integration of those specific mission-systems recommendations with one another, and the final proposed designs are presented. The feasibility, cost, and scheduling of these configurations are evaluated against assumptions of reasonable state-of-the-art growth and space funding expectations.

1973-01-01

215

Mapping of a major paleodrainage system in eastern Libya using orbital imaging radar: The Kufrah River  

NASA Astrophysics Data System (ADS)

Over the last few decades, remote sensing has revealed buried river channels in a number of regions worldwide, in many cases providing evidence of dramatic paleoenvironmental changes over Cenozoic time scales. Using orbital radar satellite imagery, we mapped a major paleodrainage system in eastern Libya, that could have linked the Kufrah Basin to the Mediterranean coast through the Sirt Basin, possibly as far back as the middle Miocene. Synthetic Aperture Radar images from the PALSAR sensor clearly reveal a 900 km-long river system, which starts with three main tributaries (north-eastern Tibesti, northern Uweinat and western Gilf Kebir/Abu Ras) that connect in the Kufrah oasis region. The river system then flows north through the Jebel Dalmah, and forms a large alluvial fan in the Sarir Dalmah. The sand dunes of the Calanscio Sand Sea prevent deep orbital radar penetration and preclude detailed reconstruction of any possible connection to the Mediterranean Sea, but a 300 km-long link to the Gulf of Sirt through the Wadi Sahabi paleochannel is likely. If this connection is confirmed, and its Miocene antiquity is established, then the Kufrah River, comparable in length to the Egyptian Nile, will have important implications for the understanding of the past environments and climates of northern Africa from the middle Miocene to the Holocene.

Paillou, Philippe; Schuster, Mathieu; Tooth, Stephen; Farr, Tom; Rosenqvist, Ake; Lopez, Sylvia; Malezieux, Jean-Marie

2009-01-01

216

Integrated radar-camera security system: experimental results  

Microsoft Academic Search

The nature of the recent military conflicts and terrorist attacks along with the necessity to protect bases, convoys and patrols have made a serious impact on the development of more effective security systems. Current widely-used perimeter protection systems with zone sensors will soon be replaced with multi-sensor systems. Multi-sensor systems can utilize day\\/night cameras, IR uncooled thermal cameras, and millimeter-wave

M. Zyczkowski; N. Palka; T. Trzcinski; R. Dulski; M. Kastek; P. Trzaskawka

2011-01-01

217

High resolution system for upper air (troposphere) wind and temperature profile measurements. [meteorological radar/Jimsphere system  

NASA Technical Reports Server (NTRS)

The Jimsphere/Jimsonde system is described and some possible applications of the system for air-sea interface measurements are presented. As space vehicles became larger and more sophisticated, an improved method for obtaining wind profile data had to be found. To satisfy this need the FPS-16 radar/Jimsphere system was developed. The Jimsphere is an aluminized mylar spherical balloon, two meters in diameter. The balloon is under superpressure, and is tracked with a high precision radar system. The development of this detailed wind profile system was started in 1963, and the present design was established in 1964. To improve the system, a program was initiated in 1965 to obtain high resolution temperature data simultaneously with the wind profile data.

Camp, D. W.; Vaughan, W. W.

1973-01-01

218

Cloud and Precipitation Radar  

NASA Astrophysics Data System (ADS)

Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.

Hagen, Martin; Höller, Hartmut; Schmidt, Kersten

219

Space object observation with radar  

NASA Astrophysics Data System (ADS)

FGAN developed a High Power Radar System, able to track and image low Earth orbiting objects, for experimental radar research. The system is unique in Germany; it consists of a narrow band tracking radar and a high resolution imaging radar. The radars are supported from one 34-m parabolic dish antenna. They operate simultaneously on the object of interest. All information which a radar can gain about physical characteristics of targets have to be extracted from the backscattered electromagnetic field of transmitted pulses. L-band tracking data provide information on range, range rate, angular direction, and radar cross-section. From high resolution polarimetric Ku-band radar data projections of the 1- and 2-dimensional scatter centre distributions are computed. This paper gives a brief description of the FGAN radar and summarizes some radar based methods for orbit analysis, orbital lifetime prediction, reconstruction of object images, assessment of object dimensions, shape, attitude, and mass.

Mehrholz, D.

1993-08-01

220

Terminal Doppler Weather Radar (TDWR) system characteristics and design constraints  

NASA Astrophysics Data System (ADS)

TDWR features two scan strategies: hazardous weather mode and monitor mode; the system has redundant transmitters, receiver/exciters, and signal processing channels. The data processing system features data base formation/conditioning, clutter residue editing, point target removal, signal-to-noise thresholding, velocity dealiasing, and a pulse-repetition frequency selection/deobscuration algorithm.

Wieler, J. G.; Shrader, W. W.

221

Terminal Doppler Weather Radar (TDWR) system characteristics and design constraints  

Microsoft Academic Search

TDWR features two scan strategies: hazardous weather mode and monitor mode; the system has redundant transmitters, receiver\\/exciters, and signal processing channels. The data processing system features data base formation\\/conditioning, clutter residue editing, point target removal, signal-to-noise thresholding, velocity dealiasing, and a pulse-repetition frequency selection\\/deobscuration algorithm.

J. G. Wieler; W. W. Shrader

1991-01-01

222

Shuttle orbiter Ku-band radar/communications system design evaluation  

NASA Technical Reports Server (NTRS)

Tasks performed in an examination and critique of a Ku-band radar communications system for the shuttle orbiter are reported. Topics cover: (1) Ku-band high gain antenna/widebeam horn design evaluation; (2) evaluation of the Ku-band SPA and EA-1 LRU software; (3) system test evaluation; (4) critical design review and development test evaluation; (5) Ku-band bent pipe channel performance evaluation; (6) Ku-band LRU interchangeability analysis; and (7) deliverable test equipment evaluation. Where discrepancies were found, modifications and improvements to the Ku-band system and the associated test procedures are suggested.

Dodds, J.; Holmes, J.; Huth, G. K.; Iwasaki, R.; Maronde, R.; Polydoros, A.; Weber, C.; Broad, P.

1980-01-01

223

A millimetre-wave MIMO radar system for threat detection in urban environments  

NASA Astrophysics Data System (ADS)

The European Defence Agency (EDA) engages countermeasures against Improvised Explosive Devices (IEDs) by funding several scientific programs on threat awareness, countermeasures IEDs or land-mine detection, in which this work is only one of numerous projects. The program, denoted as Surveillance in an urban environment using mobile sensors (SUM), covers the idea of equipping one or more vehicles of a patrol or a convoy with a set of sensors exploiting different physical principles in order to gain detailed insights of the road situation ahead. In order to give an added value to a conventional visual camera system, measurement data from an infra-red (IR) camera, a radiometer and a millimetre-wave radar are fused with data from an optical image and are displayed on a human-machine-interface (HMI) which shall assist the vehicle's co-driver to identify suspect objects or persons on or next to the road without forcing the vehicle to stop its cruise. This paper shall especially cover the role of the millimetre-wave radar sensor and its different operational modes. Measurement results are discussed. It is possible to alter the antenna mechanically which gives two choices for a field of view and angular resolution trade-off. Furthermore a synthetic aperture radar mode is possible and has been tested successfully. MIMO radar principles like orthogonal signal design were exploited tofrom a virtual array by 4 transmitters and 4 receivers. In joint evaluation, it was possible to detect e.g. grenade shells under cardboard boxes or covered metal barrels which were invisible for optical or infra-red detection.

Kirschner, A. J.; Guetlein, J.; Bertl, S.; Detlefsen, J.

2012-10-01

224

Evaluating a Radar-Based, Non Contact Streamflow Measurement System in the San Joaquin River at Vernalis, California  

USGS Publications Warehouse

Accurate measurement of flow in the San Joaquin River at Vernalis, California, is vital to a wide range of Federal and State agencies, environmental interests, and water contractors. The U.S. Geological Survey uses a conventional stage-discharge rating technique to determine flows at Vernalis. Since the flood of January 1997, the channel has scoured and filled as much as 20 feet in some sections near the measurement site resulting in an unstable stage-discharge rating. In response to recent advances in measurement techniques and the need for more accurate measurement methods, the Geological Survey has undertaken a technology demonstration project to develop and deploy a radar-based streamflow measuring system on the bank of the San Joaquin River at Vernalis, California. The proposed flow-measurement system consists of a ground-penetrating radar system for mapping channel geometries, a microwave radar system for measuring surface velocities, and other necessary infrastructure. Cross-section information derived from ground penetrating radar provided depths similar to those measured by other instruments during the study. Likewise, surface-velocity patterns and magnitudes measured by the pulsed Doppler radar system are consistent with near surface current measurements derived from acoustic velocity instruments. Since the ratio of surface velocity to mean velocity falls to within a small range of theoretical value, using surface velocity as an index velocity to compute river discharge is feasable. Ultimately, the non-contact radar system may be used to make continuous, near-real-time flow measurements during high and medium flows. This report documents the data collected between April 14, 2002 and May 17, 2002 for the purposes of testing this radar based system. Further analyses of the data collected during this field effort will lead to further development and improvement of the system.

Cheng, Ralph T.; Gartner, Jeffrey W.; Mason, Robert R.; Costa, John E.; Plant, William J.; Spicer, Kurt R.; Haeni, F. Peter; Melcher, Nick B.; Keller, William C.; Hayes, Ken

2004-01-01

225

Science Results from the MARSIS and SHARAD Subsurface Sounding Radars on Mars and their Relevance to Radar Sounding of icy Moons in the Jovian System  

NASA Astrophysics Data System (ADS)

The MARSIS and SHARAD subsurface radar sounders have been observing the Martian polar terrains, which are considered a close analogue to the material forming the crusts of Europa and Ganymede. MARSIS and SHARAD results are reviewed and discussed, and expected capabilities and challenges for similar instruments on the two Jovian moons are assessed. The model scientific payload of the Jupiter Ganymede Orbiter (JGO) in the Europa Jupiter System Mission (EJSM) includes a subsurface sounding radar experiment (SSR) to explore the upper few kilometres of the icy crust of Ganymede and, to a lesser extent, Callisto. Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) and SHAllow RADar sounder (SHARAD) are two similar experiments currently operating on Mars, carried respectively on ESA'a Mars Express and NASA's Mars Reconnaissance Orbiter. They function by transmitting a low-frequency radar pulse that is capable of penetrating below the surface, and is reflected when it encounters dielectric and structural discontinuities in the subsurface. Both MARSIS and SHARAD have observed ice deposits that are expected to be a close analogue to the material forming the crusts of the two Jovian satellites. Whereas MARSIS is optimized for deep penetration, having detected echoes down to a depth of 3.7 km over the South Polar Layered Deposits, SHARAD is capable of a tenfold-finer vertical resolution, namely 15 m or less, depending on the dielectric constant of the material being sounded. MARSIS is capable of transmitting at four different bands between 1.3 MHz and 5.5 MHz, with a 1 MHz bandwidth. SHARAD operates at a central frequency of 20 MHz transmitting a 10 MHz bandwidth. Radar sounding results on Mars from both MARSIS and SHARAD highlight the scientific capabilities of this type of experiments and show the effect of design parameter choices on instrument performance. They also prove the potential of SSR to provide unique information in the study of the geological and geophysical evolution of icy satellites. Moreover, the experience gained in the analysis of SHARAD and MARSIS echoes is very important in the design of SSR in order to develop an instrument and a set of data processing techniques capable to address the limitations observed in the Mars experiments.

Orosei, R.; Alberti, G.; Bruzzone, L.; Flamini, E.; Frigeri, A.; Heggy, E.; Kofman, W. W.; Komatsu, G.; Plaut, J. J.; Seu, R.

2010-12-01

226

A digital system to produce imagery from SAR data. [Synthetic Aperture Radar  

NASA Technical Reports Server (NTRS)

This paper describes a digital processing algorithm and its associated system design for producing images from Synthetic Aperture Radar (SAR) data. The proposed system uses the Fast Fourier Transform (FFT) approach to perform the two-dimensional correlation process. The range migration problem, which is often a major obstacle to efficient processing, can be alleviated by approximating the locus of echoes from a point target by several linear segments. SAR data corresponding to each segment is correlated separately, and the results are coherently summed to produce full-resolution images. This processing approach exhibits greatly improved computation efficiency relative to conventional digital processing methods.

Wu, C.

1976-01-01

227

A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band  

NASA Technical Reports Server (NTRS)

A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L- Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.

Kelly, Kenneth C.; Huang, John

2000-01-01

228

A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band  

NASA Technical Reports Server (NTRS)

A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L-Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.

Kelly, Kenneth C.; Huang, John

1999-01-01

229

Plastic mine detecting radar system using complex-valued self-organizing map that deals with multiple-frequency interferometric images.  

PubMed

Ground penetrating radars (GPR's) have been often applied to underground object imaging. However, conventional radar systems do not work sufficiently to detect anti-personnel plastic landmines. We propose a novel radar imaging system, which processes adaptively interferometric front-end data obtained at multiple-frequency points. The system deals with interferometric images using complex-valued self-organizing map (C-SOM). We demonstrate a successful visualization of a plastic mine buried near the ground surface. PMID:15555861

Hara, Takahiro; Hirose, Akira

2004-01-01

230

Through-the-Wall Localization of a Moving Target by Two Independent Ultra Wideband (UWB) Radar Systems  

PubMed Central

In the case of through-the-wall localization of moving targets by ultra wideband (UWB) radars, there are applications in which handheld sensors equipped only with one transmitting and two receiving antennas are applied. Sometimes, the radar using such a small antenna array is not able to localize the target with the required accuracy. With a view to improve through-the-wall target localization, cooperative positioning based on a fusion of data retrieved from two independent radar systems can be used. In this paper, the novel method of the cooperative localization referred to as joining intersections of the ellipses is introduced. This method is based on a geometrical interpretation of target localization where the target position is estimated using a properly created cluster of the ellipse intersections representing potential positions of the target. The performance of the proposed method is compared with the direct calculation method and two alternative methods of cooperative localization using data obtained by measurements with the M-sequence UWB radars. The direct calculation method is applied for the target localization by particular radar systems. As alternative methods of cooperative localization, the arithmetic average of the target coordinates estimated by two single independent UWB radars and the Taylor series method is considered. PMID:24021968

Kocur, Dušan; Švecová, Mária; Rov?áková, Jana

2013-01-01

231

Surface current patterns in the Ibiza Channel with the use of High Frequency (HF) Radar system  

NASA Astrophysics Data System (ADS)

The Ibiza Channel located between the East Coast of the Iberian Peninsula, and the West Coast of Ibiza, at the Balearic Islands, is a well-known biodiversity hot spot. This area is relevant due to the interaction of water masses coming from the Atlantic Ocean - ascending through the Iberian Peninsula coast - with the older Atlantic waters descending from the Gulf of Lion. In 2012, the installation of Coastal HF Radar in the area provides valuable information for the study of the surface transport along the channel. The Coastal HF Radar operates since June 2012, and provides hourly surface current maps with a spatial resolution of approximately 3 km and a range reaching up to 70 km offshore. The instrument forms part of a monitoring multi-platform system, which is completed with satellite-derived data, gliders, modelling and fixed and lagrangian buoys. All HF Radar data are processed with standard quality control methods. Drifter velocity obtained from lagrangian buoys for two oceanographic campaigns, satellite-derived data and currentmeter data from a fixed buoy in the Ibiza Channel are used to validate the HF Radar data. All surface current data are used to perform a spectrum analysis in order to show the physical processes, at the main temporal periods. The contribution of the different temporal scales to the total Kinetic Energy has been analysed for the first time at different seasonal intervals. This served to evaluate the energetic importance of the different components of the surface currents. The inertial currents have a lower contribution to the total KE during winter, compared with the summer period. Besides, the spatial distribution of the inertial component to the total KE varies seasonally, and according to the bathymetry of the area. The low-pass (sub-inertial) filtered HF Radar currents show a predominant northern current during the summer months in the channel, and a mean southern current during the winter period. These results are discussed and related with the external forcing, and bathymetry distribution, according to coastal or open ocean data.

Lana, Arancha; Fernández, Vicente; Troupin, Charles; Pascual, Ananda; Orfila, Alejandro; Tintoré, Joaquín

2014-05-01

232

In-flight detection of errors for enhanced aircraft flight safety and vertical accuracy improvement using digital terrain elevation data with an inertial navigation system, global positioning system and radar altimeter  

Microsoft Academic Search

This dissertation discusses integration architectures using digital terrain elevation data (DTED) with an inertial navigation system (INS), a global positioning system (GPS) and a radar altimeter. Two integration architectures are considered: DTED with INS, GPS and radar altimeter for aircraft vertical accuracy improvement during the final approach; and DTED with kinematic GPS (KGPS) and a radar altimeter for enhanced aircraft

Robert Anthony Gray

1999-01-01

233

Virtual Drive: A Complete V2X Communication and Radar System Simulator for Optimization of Multiple Antenna Systems  

Microsoft Academic Search

Vehicle-to-X (V2X) communication as well as automotive radar are fast growing areas of consumer interest. This gives rise to a challenge to a well-working communication systems in handling the V2X radio channel. The two most important components influencing the channel are the an- tennas and the fast changing environment, resulting in a time- variant behavior of the channel. Therefore, finding

Lars Reichardt; Jürgen Maurer; Thomas Fugen; Thomas Zwick

2011-01-01

234

Laser radar in robotics  

SciTech Connect

In this paper the authors describe the basic operating principles of laser radar sensors and the typical algorithms used to process laser radar imagery for robotic applications. The authors review 12 laser radar sensors to illustrate the variety of systems that have been applied to robotic applications wherein information extracted from the laser radar data is used to automatically control a mechanism or process. Next, they describe selected robotic applications in seven areas: autonomous vehicle navigation, walking machine foot placement, automated service vehicles, manufacturing and inspection, automotive, military, and agriculture. They conclude with a discussion of the status of laser radar technology and suggest trends seen in the application of laser radar sensors to robotics. Many new applications are expected as the maturity level progresses and system costs are reduced.

Carmer, D.C.; Peterson, L.M. [Environmental Research Inst. of Michigan, Ann Arbor, MI (United States)

1996-02-01

235

Digital Terrestrial Video Broadcast Interference Suppression in Forward-Looking Ground Penetrating Radar Systems  

NASA Astrophysics Data System (ADS)

In this paper we show how radio frequency interference (RFI) generated by digital video broadcasting terrestrial and digital audio broadcasting transmitters can be an important noise source for forward-looking ground penetrating radar (FLGPR) systems. Even in remote locations the average interference power sometimes exceeds ultra-wideband signals by many dB, becoming the limiting factor in the system sensitivity. The overall problem of RFI and its impact in GPR systems is briefly described and several signal processing approaches to removal of RFI are discussed. These include spectral estimation and coherent subtraction algorithms and various filter approaches which have been developed and applied by the research community in similar contexts. We evaluate the performance of these methods by simulating two different scenarios submitted to real RFI acquired with a FLGPR system developed at the Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR), (GER). The effectiveness of these algorithms in removing RFI is presented using some performance indices after suppression.

Rial, F. I.; Mendez-Rial, Roi; Lawadka, Lukasz; Gonzalez-Huici, Maria A.

2014-11-01

236

Wave and current measurements obtained using the WERA and Pisces HF radar systems and Seaview  

E-print Network

an overview of ground-based wave measuring radar. I would like to com- ment on both of these. Current from Neptune Radar Ltd) from two sites and compared with the UK Met Office depth-averaged storm- surge

Wyatt, Lucy

237

The expert system of scheduling operational modes of phased array radar  

NASA Astrophysics Data System (ADS)

In order to resolve the problems caused by traditional methods of scheduling the operational modes of phased-array radar (SOMPAR), an expert system (ES) has been designed and realized. A forward inference engine and a knowledge base with various types of knowledge representation, including the fuzzy set knowledge representation method, have been constructed. This SOMPARE ES was run on the COMPAQ 386/20, and a simulation was developed. The simulation results showed that the SOMPAR ES can obtain a scheduling conclusion on the expert level. The program is assembled with C Programming Language and is very convenient to transplant.

Lee, Xiaoyang; Cai, Qingyu

238

Performance evaluation of a Doppler radar system for wind shear detection  

NASA Technical Reports Server (NTRS)

Nonlinear stochastic differential equations are used to model wind shear, and extended Kalman filters are used to generate state estimates from measurements received from a Doppler radar onboard an aircraft. Likelihood-ratio tests are then used to detect the presence of wind shear. The performance of the system is evaluated by deriving theoretical expressions for the false alarm and miss error probabiilties. The approach uses a Fokker-Planck equation. The overall methodology is general and should be of interest in other applications.

Khalaf, Camille S.; Hibey, Joseph L.; Staton, Leo D.

1990-01-01

239

Micropower impulse radar  

Microsoft Academic Search

Invented and developed at LLNL (Lawrence Livermore National Laboratory), this inexpensive and highly sensitive radar system produces and samples extremely short pulses of energy. This novel technology is finding dozens of new uses in Laboratory programs and in sensor devices for homes, automobiles, factories, and hospitals. We have invented and patented a fundamentally different type of compact, low-power radar system

S. Azevedo; T. E. McEwan

1997-01-01

240

Real - Time Orbit Determination of Low Earth Orbit Satellites Using Radar System and SGP4 Model  

NASA Astrophysics Data System (ADS)

In case that we independently obtain orbital informations about the low earth satellites of foreign countries using radar systems, we develop the orbit determination algorithm for this purpose using a SGP4 model with an analytical orbit model and the extended Kalman filter with a real-time processing method. When the state vector is Keplerian orbital elements, singularity problems happen to compute partial derivative with respect to inclination and eccentricity orbit elements. To cope with this problem, we set state vector osculating to mean equinox and true equator cartesian elements with coordinate transformation. The state transition matrix and the covariance matrix are numerically computed using a SGP4 model. Observational measurements are the type of azimuth, elevation and range, filter process to each measurement in a lump. After analyzing performance of the developed orbit determination algorithm using TOPEX/POSEIDON POE(Precision Orbit Ephemeris), its position error has about 1 km. To be similar to performance of NORAD system that has up to 3km position accuracy during 7 days need to radar system performance that have accuracy within 0.1 degree for azimuth and elevation and 50m for range.

Lee, Jae-Kwang; Lee, Sung-Seub; Yoon, Jae-Cheol; Choi, Kyu-Hong

2003-03-01

241

HERMES: a high-speed radar imaging system for inspection of bridge decks  

SciTech Connect

Corrosion of rebar in concrete bridges causes subsurface cracks and is a major cause of structural degradation that necessitates repair or replacement. Early detection of corrosion effects can limit the location and extent of necessary repairs, while providing long-term information about the infrastructure status. Most current detection methods, however, are destructive of the road surface and require closing or restricting traffic while the tests are performed. A ground-penetrating radar imaging system has been designed and developed that will perform the nondestructive evaluation of road-bed cracking at traffic speeds; i.e., without the need to restrict traffic flow. The first-generation system (called the HERMES bridge inspector), consists of an offset-linear array of 64 impulse radar transceivers and associated electronics housed in a trailer. Computers in the trailer and in the towing vehicle control the data acquisition, processing, and display. Cross-road resolution is three centimeters at up to 30 cm in depth, while down-road resolution depends on speed; 3 cm below 20 mph up to 8 cm at 50 mph. A two-meter- wide path is inspected on each pass over the roadway. This paper, describes the design of this system, shows preliminary results, and lays out its deployment schedule.

Azevedo, S.G.

1996-10-26

242

Millimeter Wave Cloud Radar (MMCR) Handbook  

SciTech Connect

The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

KB Widener; K Johnson

2005-01-30

243

On the combined use of radar systems for multi-scale imaging of transport infrastructures  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) systems are worth to be considered as in situ non invasive diagnostic tools capable of assessing stability and integrity of transport infrastructures. As a matter of fact, by exploiting the interactions among probing electromagnetic waves and hidden objects, they provide images of the inner status of the spatial region under test from which infer risk factors, such as deformations and oxidization of the reinforcement bars as well as water infiltrations, crack and air gaps. With respect to the assessment of concrete infrastructures integrity, the reconstruction capabilities of GPR systems have been widely investigated [1,2]. However, the demand for diagnostic tools capable of providing detailed and real time information motivates the design and the performance evaluation of novel technologies and data processing methodologies aimed not only to effectively detect hidden anomalies but also to estimate their geometrical features. In this framework, this communication aims at investigating the advantages offered by the joint use of two GPR systems both of them equipped with a specific tomographic imaging approach. The first considered system is a time domain GPR equipped with a 1.5GHz shielded antenna, which is suitable for quick and good resolution surveys of the shallower layers of the structure. As second system, the holographic radar Rascan-4/4000 [3,4] is taken into account, due to its capability of providing holograms of hidden targets from the amplitude of the interference signal arising between the backscattered field and a reference signal. The imaging capabilities of both the GPR tools are enhanced by means of model based data processing approaches, which afford the imaging as a linear inverse scattering problem. Mathematical details on the inversion strategies will be provided at the conference. The combined use of the above GPR systems allows to perform multi-resolution surveys of the region under test, whose aim is, first of all, to detect hidden anomalies and then to provide a high resolution image of their geometrical features. Therefore, reliable and efficient diagnostic surveys devoted to state the healthy state of a structure can be scheduled. Numerical examples and on field validations assessing the achievable reconstruction capabilities will be provided at the conference. [1] D. J. Daniels, Ground Penetrating Radar, in IEE Radar, Sonar and Navigation Series 15, London, U.K.: IEE, 2004. [2] M. Proto, M. Bavusi, R. Bernini et al., Transport Infrastructure Surveillance and Monitoring by Electromagnetic Sensing: The ISTIMES Project, Sensors, vol.10, n.12, pp.10620-10639, 2010. [3] S. Ivashov, I. A. Vasiliev, T. D. Bechtel, C. Snapp, Comparison between impulse and holographic subsurface radar for NDT of space vehicle structural materials, Progress In Electromagnetic Research, vol.3, pp.658-661, 2004. [4] I. Catapano. L. Crocco, A. F. Morabito, F. Soldovieri, Tomographic imaging of holographic GPR data for non-invasive structural assessment: the Musmeci Bridge investigation, submitted to Nondestructive Testing and Evaluation Acknowledgement The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no 225663.

Catapano, I.; Bavusi, M.; Loperte, A.; Crocco, L.; Soldovieri, F.

2012-04-01

244

Two-dimensional imaging via a narrowband MIMO radar system with two perpendicular linear arrays.  

PubMed

This paper presents a system model and method for the 2-D imaging application via a narrowband multiple-input multiple-output (MIMO) radar system with two perpendicular linear arrays. Furthermore, the imaging formulation for our method is developed through a Fourier integral processing, and the parameters of antenna array including the cross-range resolution, required size, and sampling interval are also examined. Different from the spatial sequential procedure sampling the scattered echoes during multiple snapshot illuminations in inverse synthetic aperture radar (ISAR) imaging, the proposed method utilizes a spatial parallel procedure to sample the scattered echoes during a single snapshot illumination. Consequently, the complex motion compensation in ISAR imaging can be avoided. Moreover, in our array configuration, multiple narrowband spectrum-shared waveforms coded with orthogonal polyphase sequences are employed. The mainlobes of the compressed echoes from the different filter band could be located in the same range bin, and thus, the range alignment in classical ISAR imaging is not necessary. Numerical simulations based on synthetic data are provided for testing our proposed method. PMID:20040416

Wang, Dang-wei; Ma, Xiao-yan; Su, Yi

2010-05-01

245

Radar systems for the water resources mission. Volume 4: Appendices E-I  

NASA Technical Reports Server (NTRS)

The use of a scanning antenna beam for a synthetic aperture system was examined. When the resolution required was modest, the radar did not use all the time the beam was passing a given point on the ground to build a synthetic aperture, so time was available to scan the beam to other positions and build several images at different ranges. The scanning synthetic-aperture radar (SCANSAR) could achieve swathwidths of well over 100 km with modest antenna size. Design considerations for a SCANSAR for hydrologic parameter observation are presented. Because of the high sensitivity to soil moisture at angles of incidence near vertical, a 7 to 22 deg swath was considered for that application. For snow and ice monitoring, a 22 to 37 deg scan was used. Frequencies from X-band to L-band were used in the design studies, but the proposed system operated in C-band at 4.75 GHz. It achieved an azimuth resolution of about 50 meters at all angles, with a range resolution varying from 150 meters at 7 deg to 31 meters at 37 deg. The antenna required an aperture of 3 x 4.16 meters, and the average transmitter power was under 2 watts.

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

246

REVS: a radar-based enhanced vision system for degraded visual environments  

NASA Astrophysics Data System (ADS)

Sierra Nevada Corporation (SNC) has developed an enhanced vision system utilizing fast-scanning 94 GHz radar technology to provide three-dimensional measurements of an aircraft's forward external scene topography. This threedimensional data is rendered as terrain imagery, from the pilot's perspective, on a Head-Up Display (HUD). The image provides the requisite "enhanced vision" to continue a safe approach along the flight path below the Decision Height (DH) in Instrument Meteorological Conditions (IMC) that would otherwise be cause for a missed approach. Terrain imagery is optionally fused with digital elevation model (DEM) data of terrain outside the radar field of view, giving the pilot additional situational awareness. Flight tests conducted in 2013 show that REVS™ has sufficient resolution and sensitivity performance to allow identification of requisite visual references well above decision height in dense fog. This paper provides an overview of the Enhanced Flight Vision System (EFVS) concept, of the technology underlying REVS, and a detailed discussion of the flight test results.

Brailovsky, Alexander; Bode, Justin; Cariani, Pete; Cross, Jack; Gleason, Josh; Khodos, Victor; Macias, Gary; Merrill, Rahn; Randall, Chuck; Rudy, Dean

2014-06-01

247

Shuttle synthetic aperture radar implementation study, volume 1. [flight instrument and ground data processor system for collecting raw imaged radar data  

NASA Technical Reports Server (NTRS)

Results of an implementation study for a synthetic aperture radar for the space shuttle orbiter are described. The overall effort was directed toward the determination of the feasibility and usefulness of a multifrequency, multipolarization imaging radar for the shuttle orbiter. The radar is intended for earth resource monitoring as well as oceanographic and marine studies.

Mehlis, J. G.

1976-01-01

248

The potential of bistatic HF surface wave radar system for the surveillance of water-entry area along coastline  

Microsoft Academic Search

A bistatic\\/monostatic HF surface wave radar (HFSWR) experiment was conducted using both the transmit and receive systems of the HFSWR at Cape Race, Newfoundland and the receive system of the HFSWR at Cape Bonavista, Newfoundland. While the HFSWR at Cape Race operated in the monostatic mode, the transmitter at Cape Race and the receiver at Cape Bonavista were synchronized via

H. Leong

2006-01-01

249

A user-friendly system for synthetic aperture radar image classification based on grayscale distributional properties and context  

Microsoft Academic Search

The purpose of this paper is to present a system for the analysis and classification of Synthetic Aperture Radar (SAR) images. This system, unlike most of its competitors, allows a careful modeling of the statistical properties of the data beyond the usual Gaussian hypothesis. The modeling tools include basic descriptive measures and the choice of suited distributions, through goodness-of-fit tests,

Alejandro C. Frery; Corina Da C. F. Yanasse; Pedro R. Vieira; S. J. S. Santanna; Camilo D. Rennó

1997-01-01

250

Characterization of Adolescent Prescription Drug Abuse and Misuse Using the Researched Abuse Diversion and Addiction-Related Surveillance (RADARS[R]) System  

ERIC Educational Resources Information Center

Objective: To describe the characteristics and health effects of adolescent (age 13-19 years) prescription drug abuse and misuse using the Researched Abuse Diversion and Addiction-Related Surveillance (RADARS[R])) System. Method: Secondary analysis of data collected from RADARS System participating poison centers was performed. Data for all…

Zosel, Amy; Bartelson, Becki Bucher; Bailey, Elise; Lowenstein, Steven; Dart, Rick

2013-01-01

251

Multi-frequency synthetic-aperture imaging with a lightweight ground penetrating radar system  

NASA Astrophysics Data System (ADS)

The detection of buried objects, particularly hazardous waste containers and unexploded ordnance (UXO), has gained significant interest in the Unites States in the late 1990s. The desire to remediate the thousands of sites worldwide has become an increasing concern and the application of radar to this problem has received renewed attention. The US Department of Energy's Special Technologies Laboratory (STL), operated by Bechtel Nevada, has developed several frequency-modulated, continuous-wave (FM-CW) ground penetrating radar (GPR) units. To meet technical requirements for higher-resolution data, STL and the University of California, Santa Barbara (UCSB) is investigating advanced GPR hardware, signal processing, and synthetic-aperture imaging with the development of an innovative system. The goal is to design and fabricate a lightweight, battery-operated unit that does not require surface contact, can be operated by a novice user, and can achieve improved resolution. The latter is accomplished by using synthetic-aperture imaging, which forms the subsurface images by fully utilizing the data sequences collectively along a scan path. We also present the backward propagation algorithm as the basic structure of the multiple-frequency tomographic imaging technique, and the conventional fast Fourier transform (FFT) method which can be described as a degenerated case of the model where the computation procedure is approximated under the narrow-beam assumption.

Koppenjan, Steven K.; Allen, Curt M.; Gardner, Duane; Wong, Howard R.; Lee, Hua; Lockwood, Stephanie J.

2000-03-01

252

Evolving subglacial water systems in East Antarctica from airborne radar sounding  

NASA Astrophysics Data System (ADS)

The cold, lightless, and high pressure aquatic environment at the base of the East Antarctic Ice Sheet is of interest to a wide range of disciplines. Stable subglacial lakes and their connecting channels remain perennially liquid three kilometers below some of the coldest places on Earth. The presence of subglacial water impacts flow of the overlying ice and provides clues to the geologic properties of the bedrock below, and may harbor unique life forms which have evolved out of contact with the atmosphere for millions of years. Periodic release of water from this system may impact ocean circulation at the margins of the ice sheet. This research uses airborne radar sounding, with its unique ability to infer properties within and at the base of the ice sheet over large spatial scales, to locate and characterize this unique environment. Subglacial lakes, the primary storage mechanism for subglacial water, have been located and classified into four categories on the basis of the radar reflection properties from the sub-ice interface: Definite lakes are brighter than their surroundings by at least two decibels (relatively bright), and are both consistently reflective (specular) and have a reflection coefficient greater than -10 decibels (absolutely bright). Dim lakes are relatively bright and specular but not absolutely bright, possibly indicating non-steady dynamics in the overlying ice. Fuzzy lakes are both relatively and absolutely bright, but not specular, and may indicate saturated sediments or high frequency spatially heterogeneous distributions of sediment and liquid water (i.e. a braided steam). Indistinct lakes are absolutely bright and specular but no brighter than their surroundings. Lakes themselves and the different classes of lakes are not arranged randomly throughout Antarctica but are clustered around ice divides, ice stream onsets and prominent bedrock troughs, with each cluster demonstrating a different characteristic lake classification distribution. In the bedrock trough of Adventure Subglacial Trench, analysis of satellite altimetry is combined with radar sounding data to calculate a mass budget and infer a flow mechanism for a two cubic kilometer discharge reported to have traveled between two lakes in the region from 1996-1998. The volume released from the source lake exceeded the volume received by the destination lakes by one and a tenth cubic kilometers, indicating that some water must have escaped downstream from the lowest destination lake over the course of the event. Release of water from the source lake preceded arrival of the water at the destination lakes, 260 kilometers away, by about three months. Water continued draining from the destination lakes for several years after surface subsidence at the source lake had ceased. By 2003, a total of one and a half cubic km or nearly 75% of the water released by the source lake had traveled downstream from the destination lakes. Hydraulic modeling work indicates that the initial release of water from the source lake could have been accommodated by a self-enlarging semicircular channel. Subsequent evolution of the discharge and the three-month delay between release of water from the source lake and arrival of that water at the destination lakes indicates that a shallower and broader distributed water system is responsible for the transport of subglacial water in this region. Such a system would be more stable for the given ice-bedrock geometry and may explain the observations of intermittent flat bright bedrock reflections in radar data acquired upstream from the destination lake in 2000. For the purpose of better understanding the long-term water budget of the Dome C region, an area upstream of Adventure Trench, eleven dated isochronal internal layers within the ice penetrating radar data were tracked. An age-depth relationship, derived from the European ice core through Dome C is used to calculate strain, estimate melt, model ice temperature, and determine absolute basal reflectivity for the entire region which covers over 28,000 square kilometers.

Carter, Sasha Peter

253

Laser radar improvements  

NASA Astrophysics Data System (ADS)

A short history of the uses of various laser radars is presented, and appropriate applications of laser and microwave radars are discussed. CO2 laser radar, operating at 10.6 microns, is considered for use in aircraft navigation systems, fire-control systems for armored vehicle and aircraft, missile guidance, severe storm research, line-of-sight command of missiles, wind turbine site surveys, clear-air turbulence monitors for aircraft, and satellite tracking. Microwave radar is all-weather, but is subject to multipath inaccuracies, countermeasures, and angular resolution limitations, so hybrid laser microwave systems look promising for microwave target acquisition and laser tracking. Advantages and disadvantages of the use of ruby, YAG, and CO2 lasers in varying atmospheric conditions are discussed. Development of a laser radar pod for obstacle detection, Doppler navigation, automatic terrain following, hover control, weapon delivery, and precision searching is noted.

Jelalian, A. V.

1981-11-01

254

The System and Implementation Aspects of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS)  

NASA Technical Reports Server (NTRS)

MARSIS is a radar sounder operating in the HF frequency range to sound the surface of Mars, which will operate from the ESA Mars Express spacecraft. It is scheduled for launch from Baikonour, Russia in June 2003 and arrives in orbit around Mars in early 2004 for a two-year mission. This system is the result of an international collaboration between NASA, the Italian Space Agency (ASI), and European Space Agency (ESA). The MARSIS instrument is a 17 Kilogram total mass sounder consisting of a 40 meter tip-to-tip dipole antenna, a 7 meter long monopole antenna and the electronics module. This design of MARSIS is a tradeoff between the expected penetration into the Martian subsurface that is proportional to the wavelength of the system and the desire to operate at a short wavelength in order to minimize the effects of the ionosphere. Additional information is contained in the original extended abstract.

Jordan, R.; Biccari, D.; Bombaci, O.; Gurnett, D.; Johnson, W. T. K.; Kirchner, D.; Picardi, G.; Plaut, J.; Safaeinili, A.

2001-01-01

255

Binary selectable detector holdoff circuit: Design, testing, and application. [to laser radar data acquisition system  

NASA Technical Reports Server (NTRS)

A very high speed switching circuit, part of a laser radar data acquisition system, has been designed and tested. The primary function of this circuit was to provide computer controlled switching of photodiode detector preamplifier power supply voltages, typically less than plus or minus 20 volts, in approximately 10 nanoseconds. Thus, in actual use, detector and/or detector preamplifier damage can be avoided as a result of sudden extremely large values of backscattered radiation being detected, such as might be due to short range, very thin atmospheric dust layers. Switching of the power supply voltages was chosen over direct switching the photodiode detector input to the preamplifier, based on system noise considerations. Also, the circuit provides a synchronized trigger pulse output for triggering devices such as the Biomation Model 8100 100 MHz analog to digital converter.

Kadrmas, K. A.

1973-01-01

256

Spatial and diurnal variation of precipitation systems over Asia observed by the TRMM Precipitation Radar  

NASA Astrophysics Data System (ADS)

The spatial and diurnal variation of rainfall over Asia was investigated using the spaceborne radar data for four seasons during 1998-2003. The regional variation of the prevailing precipitation systems most closely associated with the maximum hourly rainfall was shown by examining the fine spatial distribution of rainfall amount and scale-based precipitation systems. Small precipitation systems (<102 km2) occurred most frequently around early afternoon over most land. The south facing slopes of the Himalayas, especially south of Mount Everest and the upper portion of the Brahmaputra valley, is the most obvious region of the daytime genesis of the convective systems over the Asian landmass. Over the Tibetan Plateau the occurrence of the small systems was larger than over inland India and the foothills. Large systems (>104 km2) developed mostly in the evening over nearly flat landmasses. Wide-spread systems with intense rain pixels developed over the foothills of the Himalayas in late night-early morning period, which was distinct from the daytime convection. Over ocean, in addition to the morning signature, spatially inhomogeneous and systematic characteristics were evident over the offshore region, for example, around the maritime continent. Large systems, which are strongly associated with terrain, have a great influence on the total number of rain pixels and the total amount of rainfall. For 86% of the region where large system is dominant the time of maximum rainfall is within 3 hours of the time of maximum rainfall for large systems.

Hirose, Masafumi; Nakamura, Kenji

2005-03-01

257

Road safety alerting system with radar and GPS cooperation in a VANET environment  

NASA Astrophysics Data System (ADS)

New applications in wireless environments are increasing and keeping even more interests from the developer companies and researchers. In particular, in these last few years the government and institutional organization for road safety spent a lot of resources and money to promote Vehicular Ad-Hoc Network (VANET) technology, also car manufactures are giving a lot of contributions on this field as well. In our paper, we propose an innovative system to increase road safety, matching the requests of the market allowing a cooperation between on-board devices. The vehicles are equipped with On Board Unit (OBU) and On Board Radar Unit (OBRU), which can spread alerting messages around the network regarding warning and dangerous situations exploiting IEEE802.llp standard. Vehicles move along roads observing the environment, traffic and road conditions, and vehicles parameters as well. These information can be elaborated and shared between neighbors, Road Side Unit (RSU)s and, of course, with Internet, allowing inter-system communications exploiting an Road Traffic Manager (RTM). Radar systems task it the detection of the environment in order to increase the knowledge of current conditions of the roads, for example it is important to identify obstacles, road accidents, dangerous situations and so on. Once detected exploiting onboard devices, such as Global Position System (GPS) receiver it is possible to know the exact location of the caught event and after a data elaboration the information is spread along the network. Once the drivers are advised, they can make some precautionary actions such as reduction of traveling speed or modification of current road path. In this work the routing algorithms, which have the main goal to rapidly disseminate information, are also been investigated.

Santamaria, Amilcare Francesco; Sottile, Cesare; De Rango, Floriano; Voznak, Miroslav

2014-05-01

258

Nonlinear filtering for tracking large objects in radar imagery  

NASA Astrophysics Data System (ADS)

Detecting and tracking a moving ground target in radar imagery is a challenge intensified by clutter, sensor anomalies, and the substantial signature variations that occur when a target's aspect angle changes rapidly. In its GMTI mode, a radar produces range-Doppler images that contain both kinematic reports and shape features. An HRR signature, when formed as the Fourier transform of the range-Doppler image across its Doppler dimension, becomes a derived measurement and an alternative source of identity information. Although HRR signatures can vary enormously with even small changes in target aspect, such signatures were vital for associating kinematic reports to tracks in this work. This development started with video phase history (VPH) data recorded from a live experiment involving a GMTI radar viewing a single moving target. Since the target could appear anywhere in the range-Doppler image derived from the VPH data, the goal was to localize it in a small range-Doppler "chip" that could be extracted and used in subsequent research. Although the clutter in any given VPH frame generally caused false chips to be formed in the full range-Doppler image, at most one chip contained the target. The most effective approach for creating any chip is to ensure that the object is present in the return from each pulse that contributes to that chip, and to correct any phase distortions arising from range gate changes. Processing constraints dictated that the algorithm for target chip extraction be coded in MATLAB with a time budget of a few seconds per frame. Furthermore, templates and shape models to describe the target were prohibited. This paper describes the nonlinear filtering approach used to reason over multiple frames of VPH data. This nonlinear approach automatically detects and segments potential targets in the range-Doppler imagery, and then extracts kinematic and shape features that are tracked over multiple data frames to ensure that the real target is in the declared chip. The algorithm described was used successfully to process over 84,000 frames of real data without human assistance.

Greenewald, John H.; Musick, Stanton H.

2005-05-01

259

Micropower impulse radar imaging  

SciTech Connect

From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

Hall, M.S.

1995-11-01

260

Volumetric analysis of a New England barrier system using ground-penetrating-radar and coring techniques  

USGS Publications Warehouse

Ground-penetrating-radar (GPR) profiles calibrated with core data allow accurate assessments of coastal barrier volumes. We applied this procedure successfully to the barrier system along Saco Bay, Maine (USA), as part of a sediment-budget study that focused on present-day sand volumes in various coastal, shoreface, and inner-shelf lith-osomes, and on sand fluxes that have affected the volume or distribution of sand in these sediment bodies through time. On GPR profiles, the components of the barrier lithosome are readily differentiated from other facies, except where the radar signal is attenuated by brackish or salty groundwater. Significant differences between dielectric properties of the barrier lithosome and other units commonly result in strong boundary reflectors. The mostly sandy barrier sediments allow deep penetration of GPR waves, in contrast to finer-grained strata and till-covered bedrock. Within the Saco Bay barrier system, 22 ??3 x 106 m3 of sediment are unevenly distributed. Two-thirds of the total barrier volume is contained within the northern and southern ends of the study area, in the Pine Point spit and the Ferry Beach/Goosefare complex, respectively. The central area around Old Orchard Beach is locally covered by only a thin veneer of barrier sand, averaging <3 m, that unconformably overlies shallow pre-Holocene facies. The prominence of barrier-spit facies and the distribution pattern of back-barrier sediments indicate that a high degree of segmentation, governed by antecedent topography, has affected the development of the Saco Bay barrier system. The present-day configuration of the barrier and back-barrier region along Saco Bay, however, conceals much of its early compartmentalized character.

Van Heteren, S.; FitzGerald, D.M.; Barber, D.C.; Kelley, J.T.; Belknap, D.F.

1996-01-01

261

Advances in Radar Technology for Bird Strike Risk Assessment  

Microsoft Academic Search

Since the 2001 BSC meeting in Calgary, Geo-Marine, Inc. has made dramatic advances in the development of avian radar systems. The Mobile Avian Radar System (MARS) has undergone major revisions. New radar processor cards provide the computer workstations with higher resolution data than was previously possible. The system now incorporates both horizontal- and vertical-scanning radars. The vertical scanning radar antenna

T. Adam Kelly; Ronald Merritt; Ronald L. White; Mark Howera; Timothy West

2002-01-01

262

A Three-Dimensional Ray Tracing Simulation of a Synthetic Aperture Ground Penetrating Radar System  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) is a useful tool for imaging the area below the Earth's surface. GPR works on the same principle as traditional radar, evaluating the electromagnetic returns reflected from an object or scene of interest to determine characteristics of the object that reflected the signal. Synthetic Aperture Radar (SAR) is a technique which combines radar returns of a given scene collected at several positions. By compiling the information contained in the returns, an image of a scene can be generated. Combining these two concepts allows us to create an image of an underground scene.

Jeter, James W., III

2002-10-01

263

Implementation and evaluation of coherent synthetic aperture radar processing for level measurements of bulk goods with an FMCW-system  

NASA Astrophysics Data System (ADS)

In industrial process measurement instrumentation, radar systems are well established for the measurement of filling levels of liquids in tanks. Level measurements of bulk goods in silos, on the other hand, are more challenging because the material is heaped up and its surface has typically a relatively complex shape. In this paper, the application of synthetic aperture radar (SAR) reconstruction with a frequency modulated continuous wave (FMCW) radar system for level measurements of bulk goods is evaluated. In the proposed monostatic setup, echo signals are acquired at discrete antenna positions on top of the silo. Spatially resolved information about the surface contour of a bulk good heap is reconstructed by coherent 'delay and sum' processing. The concept has been experimentally evaluated with a 24 to 26 GHz FMCW radar system mounted on a linear stepping motor positioning unit. Measurements on a thin metal wire at different range and on a curved test-object with a diffusely scattering surface have been performed to analyze the system's point spread function (PSF) and performance. Constant range and azimuth resolutions (-6 dB) of 15 cm and 8 cm, respectively, have been obtained up to a range of 6 m, and results of further evaluations show that the proposed concept allows more accurate and reliable level reconstructions of surface profiles compared to the conventional approach with measurements at a single antenna position.

Vogt, M.; Gerding, M.; Musch, T.

2010-09-01

264

Sensitivity of S- and Ka-band matched dual-wavelength radar system for detecting nonprecipitating cloud  

Microsoft Academic Search

Remote detection of cloud phase in either liquid, ice or mixed form a key microphysical observation. Evolution of a cloud system and associated radiative properties depend on microphysical characteristics. Polarization radars rely on the shape of the particle to delineate the regions of liquid and ice. For specified transmitter and receiver characteristics, it is easier to detect a high concentrations

J. Vivekanandan; Marcia Politovich; Robert Rilling; Scott Ellis; Frank Pratte

2004-01-01

265

Adaptive phased array radar processing on a multi-channel, acousto-optic, linear algebra system - Experimental results  

Microsoft Academic Search

The use of a high accuracy optical processor to obtain the optimal solution for the weight vector in the adaptive phased array radar (APAR) problem is discussed. This optical system is a multichannel, acoustooptic architecture which obtains high accuracy results through the encoding of the numerical data as bit stream which are processed optically. The actual accuracy is based upon

C. W. Carroll; B. V. K. Vijaya Kumar

1988-01-01

266

Radar principles  

NASA Technical Reports Server (NTRS)

Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

Sato, Toru

1989-01-01

267

Use of compact synthetic aperture radar systems to assist with device detection and discrimination  

NASA Astrophysics Data System (ADS)

NuSAR (Naval Research Laboratory Unmanned Synthetic Aperture Radar) is a sensor developed under the ONRfunded FEATHAR (Fusion, Exploitation, Algorithms, and Targeting for High-Altitude Reconnaissance) program. FEATHAR is being directed and executed by the Naval Research Laboratory (NRL) in conjunction with the Space Dynamics Laboratory (SDL). FEATHAR's goal is to develop and test new tactical sensor systems specifically designed for small manned and unmanned platforms (payload weight < 50 lbs). NuSAR is a novel dual-band (L- and X-band) SAR capable of a variety of tactically relevant operating modes and detection capabilities. Flight test results will be described for narrow and wide bandwidth and narrow and wide azimuth aperture operating modes.

Jensen, Mark; Walls, Thomas J.; Anderson, Scott A.; Linne von Berg, Dale; Holt, Niel; Kruer, Melvin; Long, David G.; Wilson, Michael L.

2010-04-01

268

Ground penetrating detection using miniaturized radar system based on solid state microwave sensor.  

PubMed

We propose a solid-state-sensor-based miniaturized microwave radar technique, which allows a rapid microwave phase detection for continuous wave operation using a lock-in amplifier rather than using expensive and complicated instruments such as vector network analyzers. To demonstrate the capability of this sensor-based imaging technique, the miniaturized system has been used to detect embedded targets in sand by measuring the reflection for broadband microwaves. Using the reconstruction algorithm, the imaging of the embedded target with a diameter less than 5 cm buried in the sands with a depth of 5 cm or greater is clearly detected. Therefore, the sensor-based approach emerges as an innovative and cost-effective way for ground penetrating detection. PMID:24387449

Yao, B M; Fu, L; Chen, X S; Lu, W; Guo, H; Gui, Y S; Hu, C-M

2013-12-01

269

Target position localization in a passive radar system through convex optimization  

NASA Astrophysics Data System (ADS)

This paper proposes efficient target localization methods for a passive radar system using bistatic time-of-arrival (TOA) information measured at multiple synthetic array locations, where the position of these synthetic array locations is subject to random errors. Since maximum likelihood (ML) formulation of this target localization problem is a non-convex optimization problem, semi-definite relaxation (SDR)-based optimization methods in general do not provide satisfactory performance. As a result, approximated ML optimization problems are proposed and solved with SDR plus bisection methods. For the case without position errors, it is shown that the relaxation guarantees a rank-one solution. The optimization problem for the case with position errors involves only a relaxation of a scalar quadratic term. Simulation results show that the proposed algorithms outperform existing methods and provide mean square position error performance very close to the Cramer-Rao lower bound even for larger values of noise and position estimation errors.

Chalise, Batu K.; Zhang, Yimin D.; Amin, Moeness G.; Himed, Braham

2013-05-01

270

A new algorithm for radar emitter recognition  

Microsoft Academic Search

A radar electronic support measures (ESM) system performs the functions of threat detection and area surveillance. The received radar pulses are sorted and segregated by the deinterleaver into a number of radar cells depending on the measured parameters of the received pulses. These radar cells will be submitted to the threat library and compared with the stored parameters of known

H. E. Hassan

2003-01-01

271

Joint deinterleaving\\/recognition of radar pulses  

Microsoft Academic Search

A radar electronic support measures (ESM) system performs the functions of threat detection and area surveillance to determine the bearing and the identity of the surrounding radar emitters. The received pulses arc sorted and segregated into a number of deinterleaved radar cells depending on their measured parameters. The parameters of the deinterleaved radar cells will be submitted to the threat

H. E. Hassan

2003-01-01

272

Radar, Insect Population Ecology, and Pest Management  

NASA Technical Reports Server (NTRS)

Discussions included: (1) the potential role of radar in insect ecology studies and pest management; (2) the potential role of radar in correlating atmospheric phenomena with insect movement; (3) the present and future radar systems; (4) program objectives required to adapt radar to insect ecology studies and pest management; and (5) the specific action items to achieve the objectives.

Vaughn, C. R. (editor); Wolf, W. (editor); Klassen, W. (editor)

1979-01-01

273

Spaceborne weather radar  

NASA Technical Reports Server (NTRS)

The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

Meneghini, Robert; Kozu, Toshiaki

1990-01-01

274

Impact of Wavelet based signal processing methods in radar classification systems using Hidden Markov Models  

Microsoft Academic Search

A classification technology is presented that uses a Wavelet based feature extractor and a Hidden Markov Model (HMM) to classify simulated and real radar signals from six classes of targets: person, tracked vehicles, wheeled vehicles, helicopters, propeller aircrafts and clutter (no match). Similar to techniques that have been well proven in speech and image recognition, the time-varying nature of radar

G. Kouemou; F. Opitz

2008-01-01

275

High speed data acquisition systems for ISRO's airborne and spaceborne radars  

Microsoft Academic Search

During 1990's, high speed data handling and control unit (DHCU) was developed for Indian Space Research Organisation's (ISRO) C-band airborne synthetic aperture radar (ASAR) at Space Applications Centre (SAC), ISRO, India. It has been extensively utilised to acquire high bandwidth radar signal during ASAR flights aboard Beechcraft-200 aircraft, conducted regularly since 1997. DHCU supports ASAR data acquisition, formatting and storage.

N. M. Desai; R. Agrawal; J. G. Vachhani; V. R. Gujraty; S. S. Rana

2003-01-01

276

78 FR 19063 - Airworthiness Approval for Aircraft Forward-Looking Windshear and Turbulence Radar Systems  

Federal Register 2010, 2011, 2012, 2013

...functionalities in Technical Standard Order (TSO)-C63d, Airborne Weather Radar Equipment. The objective is to leverage the installation...as additional functionality added to TSO-C63c, Airborne Weather and Ground Mapping Pulsed Radars. The FAA and industry...

2013-03-28

277

Radar applications overview  

NASA Astrophysics Data System (ADS)

During the fifty years since its initial development as a means of providing early warning of airborne attacks against allied countries during World War II, radar systems have developed to the point of being highly mobile and versatile systems capable of supporting a wide variety of remote sensing applications. Instead of being tied to stationary land-based sites, radar systems have found their way into highly mobile land vehicles as well as into aircraft, missiles, and ships of all sizes. Of all these applications, however, the most exciting revolution has occurred in the airborne platform arena where advanced technology radars can be found in all shapes and sizes...ranging from the large AWACS and Joint STARS long range surveillance and targeting systems to small millimeter wave multi-spectral sensors on smart weapons that can detect and identify their targets through the use of highly sophisticated digital signal processing hardware and software. This paper presents an overview of these radar applications with the emphasis on modern airborne sensors that span the RF spectrum. It will identify and describe the factors that influence the parameters of low frequency and ultra wide band radars designed to penetrate ground and dense foliage environments and locate within them buried mines, enemy armor, and other concealed or camouflaged weapons of war. It will similarly examine the factors that lead to the development of airborne radar systems that support long range extended endurance airborne surveillance platforms designed to detect and precision-located both small high speed airborne threats as well as highly mobile time critical moving and stationary surface vehicles. The mission needs and associated radar design impacts will be contrasted with those of radar systems designed for high maneuverability rapid acquisition tactical strike warfare platforms, and shorter range cued air-to-surface weapons with integral smart radar sensors.

Greenspan, Marshall

1996-06-01

278

MIMO Radar System for Respiratory Monitoring Using Tx and Rx Modulation with M-Sequence Codes  

NASA Astrophysics Data System (ADS)

The importance of respiratory monitoring systems during sleep have increased due to early diagnosis of sleep apnea syndrome (SAS) in the home. This paper presents a simple respiratory monitoring system suitable for home use having 3D ranging of targets. The range resolution and azimuth resolution are obtained by a stepped frequency transmitting signal and MIMO arrays with preferred pair M-sequence codes doubly modulating in transmission and reception, respectively. Due to the use of these codes, Gold sequence codes corresponding to all the antenna combinations are equivalently modulated in receiver. The signal to interchannel interference ratio of the reconstructed image is evaluated by numerical simulations. The results of experiments on a developed prototype 3D-MIMO radar system show that this system can extract only the motion of respiration of a human subject 2m apart from a metallic rotatable reflector. Moreover, it is found that this system can successfully measure the respiration information of sleeping human subjects for 96.6 percent of the whole measurement time except for instances of large posture change.

Miwa, Takashi; Ogiwara, Shun; Yamakoshi, Yoshiki

279

Equatorial MU Radar project  

NASA Astrophysics Data System (ADS)

Research Institute for Sustainable Humanosphere, Kyoto University (RISH) has been studying the atmosphere by using radars. The first big facility was the MU (Middle and Upper atmosphere) radar installed in Shiga, Japan in 1984. This is one of the most powerful and multi-functional radar, and is successful of revealing importance of atmospheric waves for the dynamical vertical coupling processes. The next big radar was the Equatorial Atmosphere Radar (EAR) installed at Kototabang, West Sumatra, Indonesia in 2001. The EAR was operated under close collaboration with LAPAN (Indonesia National Institute for Aeronautics and Space), and conducted the long-term continuous observations of the equatorial atmosphere/ionosphere for more than 10 years. The MU radar and the EAR are both utilized for inter-university and international collaborative research program for long time. National Institute for Polar Research (NIPR) joined EISCAT Scientific Association together with Nagoya University, and developed the PANSY radar at Syowa base in Antarctica as a joint project with University of Tokyo. These are the efforts of radar study of the atmosphere/ionosphere in the polar region. Now we can find that Japan holds a global network of big atmospheric/ionospheric radars. The EAR has the limitation of lower sensitivity compared with the other big radars shown above. RISH now proposes a plan of Equatorial MU Radar (EMU) that is to establish the MU-radar class radar next to the EAR. The EMU will have an active phased array antenna with the 163m diameter and 1055 cross-element Yagis. Total output power of the EMU will be more than 500kW. The EMU can detect turbulent echoes from the mesosphere (60-80km). In the ionosphere incoherent-scatter observations of plasma density, drift, and temperature would be possible. Multi-channel receivers will realize radar-imaging observations. The EMU is one of the key facilities in the project "Study of coupling processes in the solar-terrestrial system" for Master Plan 2014 of the Science Council of Japan (SCJ). We show the EMU project and its science in the presentation.

Yamamoto, Mamoru; Hashiguchi, H.; Tsuda, Toshitaka; Yamamoto, Masayuki

280

An integrated maritime surveillance system based on high-frequency surface-wave radars. 1. Theoretical background and numerical simulations  

Microsoft Academic Search

An integrated maritime surveillance (IMS) system, based on high-frequency surface-wave radars (HFSWR), is described. IMS provides low-cost, 24-hour, real-time, over-the-horizon surveillance of large ocean areas, out to the 200 nautical mile Exclusive Economic Zone (EEZ). The system can be used to coordinate search and rescue operations, and to combat smuggling, drug trafficking, illegal dumping of pollutants, and other undesirable activities.

Levenf Sevgi; Anthony Ponsford; H. C. Chan

2001-01-01

281

Real time control of a combined sewer system using radar-measured precipitation - results of the pilot study  

Microsoft Academic Search

Emschergenossenschaft and Lippeverband have developed a method to use radar-measured precipitation as an input for a real-time control of a combined sewer system containing several overflow structures. Two real-time control strategies have been developed and tested, one is solely volume-based, the other is volume and pollution-based. The system has been implemented in a pilot study in Gelsenkirchen, Germany. During the

A. Petruck; E. Holtmeier; A. Redder; B. Teichgräber

282

UWB 3.1–10.6 GHz CMOS transmitter for system-on-a-chip nano-power pulse radars  

Microsoft Academic Search

The building blocks of the transmitter for system-on-a-chip CMOS nano-power radar systems are presented. They consist of a novel fully integrated UWB pulse generator and a digitally programmable delay element. The pulse generator provides monocycle pulses with duration time close to 250 ps and 1-V peak-to-peak amplitude. In detail, the circuit provides a sinusoidal-like monocycle when activated by a negative

Fabio Zito; Domenico Zito; Domenico Pepe

2007-01-01

283

Evaluating and managing Cold War era historic properties : the cultural significance of U.S. Air Force defensive radar systems.  

SciTech Connect

Aircraft and later missile radar early warning stations played an important role in the Cold War. They are associated with important technological, social, political, and military themes of the Cold War and are worthy of preservation. The scope and scale of these systems make physical preservation impractical, but the U.S. Air Force program of historical evaluation and documentation of these systems will provide valuable information to future generations studying this historic period.

Whorton, M.

1999-01-20

284

Development of a noncontact and long-term respiration monitoring system using microwave radar for hibernating black bear.  

PubMed

The aim of this study is to develop a prototype system for noncontact, noninvasive and unconstrained vital sign monitoring using microwave radar and to use the system to measure the respiratory rate of a Japanese black bear (Ursus thibetanus japonicus) during hibernation for ensuring the bear's safety. Ueno Zoological Gardens in Tokyo planned to help the Japanese black bear (female, approximately 2 years of age) going into hibernation. The prototype system has a microwave Doppler radar antenna (10-GHz frequency, approximately 7 mW output power) for measuring motion of the body surface caused by respiratory activity without making contact with the body. Monitoring using this system was conducted from December 2006 to April 2007. As a result, from December 18, 2006, to March 17, 2007, similar behaviors reported by earlier studies were observed, such as sleeping with curled up posture and not eating, urinating or defecating. During this hibernation period and also around the time of hibernation, the prototype system continuously measured cyclic oscillations. The presence of cyclic vibrations at 8-sec intervals (about 7 bpm) was confirmed by the system before she entered hibernation on December 3, 2006. The respiratory rate gradually decreased, and during the hibernation period the respiratory rate was extremely low at approximately 2 bpm with almost no change. The results show that motion on the body surface caused by respiratory activity can be measured without touching the animal's body. Thus, the microwave radar employed here can be utilized as an aid in observing vital signs of animals. PMID:19504598

Suzuki, Satoshi; Matsui, Takemi; Kawahara, Hiroshi; Gotoh, Shinji

2009-05-01

285

Exploiting robust direct data domain STAP for GMTI in very high resolution SAR  

Microsoft Academic Search

In this paper we exploit the robust direct data domain STAP (RD3-STAP) in the SAR case. This is extremely interesting especially for very high resolution SAR systems. In fact, in this case due to the strong heterogeneous characteristics of the clutter over range, stochastic STAP might fail due to the possible lack of enough homogeneous secondary data for adequate clutter

Diego Cristallini; Fraunhofer FHR

2012-01-01

286

Planetary Radar Astronomy  

NASA Technical Reports Server (NTRS)

Radar is a powerful technique that has furnished otherwise unavailable information about solar system bodies for three decades. The advantages of radar in planetary astronomy result from: (1) the observer's control of all the attributes of the coherent signal used to illuminate the target, especially the wave form's time/frequency modulation and polarization; (2) the ability of radar to resolve objects spatially via measurements of the distribution of echo power in time delay and Doppler frequency; (3) the pronounced degree to which delay-Doppler measurements constrain orbits and spin vectors; and (4) centimeter-to-meter wavelengths, which easily penetrate optically opaque planetary clouds and cometary comae, permit investigation of near-surface macrostructure and bulk density, and are sensitive to high concentrations of metal or, in certain situations, ice. Planetary radar astronomy has primarily involved observations with Earth-based radar telescopes, but also includes some experiments with a spaceborne transmitter or receiver. In addition to providing a wealth of information about the geological and dynamical properties of asteroids, comets, the inner planets, and natural satellites, radar experiments have established the scale of the solar system, have contributed significantly to the accuracy of planetary ephemerides, and have helped to constrain theories of gravitation. This review outlines radar astronomical techniques and describes principal observational results.

Ostro, Steven J.

1993-01-01

287

Determination of the effectiveness of commercial-off-the-shelf radar in the cuing of unmanned aerial vehicle pan-tilt-zoom camera systems  

NASA Astrophysics Data System (ADS)

This study examined the use of low-cost commercial-off-the-shelf (COTS) radar in support of the cuing of pan-tilt-zoom (PTZ) optical payload systems. Cancellation of the U.S. Navy's vertical take off and landing (VTOL) unmanned aerial vehicle (VTUAV) program left the Navy without a UAV with radar sensor capability. Using a UAV PTZ optical payload and a COTS radar, this study collected specific time difference measurements between PTZ optical payload searches without radar cuing and searches with radar cuing. In every test run conducted, searches with radar cuing reduced PTZ optical payload detection time. The study showed that a low-cost COTS radar mounted on a small UAV can meet some of the radar requirements lost with cancellation of the VTUAV program. The study results could have a direct impact on myriad of U.S. Navy and other U.S. government surveillance requirements, especially the monitoring of U.S. coastal waters in support of homeland security goals and objectives.

Ford, Patrick Joseph

288

Bird-aircraft strike avoidance radar  

Microsoft Academic Search

Avian radar system has been developed for bird-aircraft strike hazard avoidance. Two representative systems, which are countrywide and airport-based avian radar systems, are surveyed to summarize the state-of-the-art in this research field. Avian radar experimental system built by Beihang University is introduced in detail, including system architecture, performance analysis, and processing algorithm for bird target detection and tracking. This radar

Ning Huansheng; Chen Weishi; Mao Xia; Li Jing

2010-01-01

289

Micropower impulse radar  

SciTech Connect

Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s Laser Directorate stem from Nova`s transient digitizer. The MIR`s extraordinary range of applications include security, search and rescue, life support, nondestructive evaluation, and transportation.

Azevedo, S.; McEwan, T.E.

1996-01-01

290

A Tower-based Prototype VHF/UHF Radar for Subsurface Sensing: System Description and Data Inversion Results  

NASA Technical Reports Server (NTRS)

Knowledge of subsurface characteristics such as permittivity variations and layering structure could provide a breakthrough in many terrestrial and planetary science disciplines. For Earth science, knowledge of subsurface and subcanopy soil moisture layers can enable the estimation of vertical flow in the soil column linking surface hydrologic processes with that in the subsurface. For planetary science, determining the existence of subsurface water and ice is regarded as one of the most critical information needs for the study of the origins of the solar system. The subsurface in general can be described as several near-parallel layers with rough interfaces. Each homogenous rough layer can be defined by its average thickness, permittivity, and rms interface roughness assuming a known surface spectral distribution. As the number and depth of layers increase, the number of measurements needed to invert for the layer unknowns also increases, and deeper penetration capability would be required. To nondestructively calculate the characteristics of the rough layers, a multifrequency polarimetric radar backscattering approach can be used. One such system is that we have developed for data prototyping of the Microwave Observatory of Subcanopy and Subsurface (MOSS) mission concept. A tower-mounted radar makes backscattering measurements at VHF, UHF, and L-band frequencies. The radar is a pulsed CW system, which uses the same wideband antenna to transmit and receive the signals at all three frequencies. To focus the beam at various incidence angles within the beamwidth of the antenna, the tower is moved vertically and measurements made at each position. The signals are coherently summed to achieve focusing and image formation in the subsurface. This requires an estimate of wave velocity profiles. To solve the inverse scattering problem for subsurface velocity profile simultaneously with radar focusing, we use an iterative technique based on a forward numerical solution of the layered rough surface problem. The layers are each defined in terms of a small number of unknown distributions as given above. An a priori estimate of the solution is first assumed, based on which the forward problem is solved for the backscattered measurements. This is compared with the measured data and using iterative techniques an update to the solution for the unknowns is calculated. The process continues until convergence is achieved. Numerical results will be shown using actual radar data acquired with the MOSS tower radar system in Arizona in Fall 2003, and compared with in-situ measurements.

Moghaddam, Mahta; Pierce, Leland; Tabatabaeenejad, Alireza; Rodriguez, Ernesto

2005-01-01

291

Radar absorbing material (RAM) and shaping on radar cross section reduction of dihedral corners  

Microsoft Academic Search

How far can a radar system detect an object depends the radar cross section (RCS) of the target. Corner reflectors are the major scattering centers in the radar signatures of vehicles. The monostatic return from such structures can be reduced by ensuring that surfaces never meet at right angles and by application of radar absorbing materials (RAM). This paper deals

G. G. Peixoto; A. L. de Paula; L. A. Andrade; C. M. A. Lopes; M. C. Rezende

2005-01-01

292

Overview of Doppler Radar Observations of Precipitating Cloud Systems in Sumatera Island During the First CPEA Campaign  

Microsoft Academic Search

During the latter half of the first CPEA campaign (CPEA-I), X-band Doppler radar (XDR) observation was carried out from 10 April to 9 May 2004 in west Sumatera. In this paper, characteristics of precipitating systems and their relation to the Madden-Julian Oscillation (MJO) are investigated based on the analysis of the XDR data. Significant diurnal variations of precipitation were observed

Masayuki KAWASHIMA; Yasushi FUJIYOSHI; Masayuki OHI; Tetsuya HONDA; Toshiaki KOZU; Toyoshi SHIMOMAI; Hiroyuki HASHIGUCHI

2006-01-01

293

The NASA radar entomology program at Wallops Flight Center  

NASA Technical Reports Server (NTRS)

NASA contribution to radar entomology is presented. Wallops Flight Center is described in terms of its radar systems. Radar tracking of birds and insects was recorded from helicopters for airspeed and vertical speed.

Vaughn, C. R.

1979-01-01

294

Phased-array radars  

NASA Astrophysics Data System (ADS)

The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.

Brookner, E.

1985-02-01

295

Development of an ultra wide band microwave radar based footwear scanning system  

NASA Astrophysics Data System (ADS)

At airports, security screening can cause long delays. In order to speed up screening a solution to avoid passengers removing their shoes to have them X-ray scanned is required. To detect threats or contraband items hidden within the shoe, a method of screening using frequency swept signals between 15 to 40 GHz has been developed, where the scan is carried out whilst the shoes are being worn. Most footwear is transparent to microwaves to some extent in this band. The scans, data processing and interpretation of the 2D image of the cross section of the shoe are completed in a few seconds. Using safe low power UWB radar, scattered signals from the shoe can be observed which are caused by changes in material properties such as cavities, dielectric or metal objects concealed within the shoe. By moving the transmission horn along the length of the shoe a 2D image corresponding to a cross section through the footwear is built up, which can be interpreted by the user, or automatically, to reveal the presence of concealed threat within the shoe. A prototype system with a resolution of 6 mm or less has been developed and results obtained for a wide range of commonly worn footwear, some modified by the inclusion of concealed material. Clear differences between the measured images of modified and unmodified shoes are seen. Procedures for enhancing the image through electronic image synthesis techniques and image processing methods are discussed and preliminary performance data presented.

Rezgui, Nacer Ddine; Bowring, Nicholas J.; Andrews, David A.; Harmer, Stuart W.; Southgate, Matthew J.; O'Reilly, Dean

2013-10-01

296

Polarimetric synthetic aperture radar image unsupervised classification method based on artificial immune system  

NASA Astrophysics Data System (ADS)

An unsupervised classification method based on the H/? classifier and artificial immune system (AIS) is proposed to overcome the inefficiencies that arise when traditional classification methods deal with polarimetric synthetic aperture radar (PolSAR) data having large numbers of overlapping pixels and excess polarimetric information. The method is composed of two steps. First, Cloude-Pottier decomposition is used to obtain the entropy H and the scattering angle ?. The classification result based on the H/? plane is used to initialize the AIS algorithm. Second, to obtain accurate results, the AIS clonal selection algorithm is used to perform an iterative calculation. As a self-organizing, self-recognizing, and self-optimizing algorithm, the AIS is able to obtain a global optimal solution and better classification results by making use of both the scattering mechanism of ground features and polarimetric scattering characteristics. The effectiveness and feasibility of this method are demonstrated by experiments using a NASA-JPL PolSAR image and a high-resolution PolSAR image of Lingshui autonomous county in Hainan Province.

Jie, Yu; Gang, Wang; Teng, Zhu; Xiaojuan, Li; Qin, Yan

2014-01-01

297

MIDAS-W: a workstation-based incoherent scatter radar data acquisition system  

NASA Astrophysics Data System (ADS)

The Millstone Hill Incoherent Scatter Data Acquisition System (MIDAS) is based on an abstract model of an incoherent scatter radar. This model is implemented in a hierarchical software system, which serves to isolate hardware and low-level software implementation details from higher levels of the system. Inherent in this is the idea that implementation details can easily be changed in response to technological advances. MIDAS is an evolutionary system, and the MIDAS hardware has, in fact, evolved while the basic software model has remained unchanged. From the earliest days of MIDAS, it was realized that some functions implemented in specialized hardware might eventually be implemented by software in a general-purpose computer. MIDAS-W is the realization of this concept. The core component of MIDAS-W is a Sun Microsystems UltraSparc 10 workstation equipped with an Ultrarad 1280 PCI bus analog to digital (A/D) converter board. In the current implementation, a 2.25 MHz intermediate frequency (IF) is bandpass sampled at 1 µs intervals and these samples are multicast over a high-speed Ethernet which serves as a raw data bus. A second workstation receives the samples, converts them to filtered, decimated, complex baseband samples and computes the lag-profile matrix of the decimated samples. Overall performance is approximately ten times better than the previous MIDAS system, which utilizes a custom digital filtering module and array processor based correlator. A major advantage of MIDAS-W is its flexibility. A portable, single-workstation data acquisition system can be implemented by moving the software receiver and correlator programs to the workstation with the A/D converter. When the data samples are multicast, additional data processing systems, for example for raw data recording, can be implemented simply by adding another workstation with suitable software to the high-speed network. Testing of new data processing software is also greatly simplified, because a workstation with the new software can be added to the network without impacting the production system. MIDAS-W has been operated in parallel with the existing MIDAS-1 system to verify that incoherent scatter measurements by the two systems agree. MIDAS-W has also been used in a high-bandwidth mode to collect data on the November, 1999, Leonid meteor shower.

Holt, J. M.; Erickson, P. J.; Gorczyca, A. M.; Grydeland, T.

2000-09-01

298

Installation of a Permanent Doppler Radar Monitoring System at Colima Volcano, Mexico, and its use for Eruption Cloud Modelling  

NASA Astrophysics Data System (ADS)

In February 2007 we installed a standalone Doppler radar monitoring station at Colima volcano, Mexico. During that time, a new episode of dome growth was underway with daily Vulcanian eruptive events occurring. These were continuously recorded with the Doppler radar. In December 2008 we upgraded the monitoring station with a second Doppler radar, a network video camera, and a direct WLAN connection to the 28.5km distant Colima University, which allows us to remotely reconfigure the whole system in times of volcanic crises. A custom made data logger collects and stores all data at the station before transmitting data in packages to the office. The entire system is powered by solar panels. The camera is triggered by the Doppler radar that is aimed at the vent. In case an eruption is detected, the camera switches from taking pictures at arbitrary intervals to continuous video recording until the end of the eruption. Similarly the Doppler radar switches to a high sampling rate (15Hz). In 2007 we recorded 92 events during six months with durations of 20 to 200 seconds. The velocity spectra clearly show two regimes: (a) buoyant updraft with 20 to 60 seconds of constant velocities and a maximum of 20 m/s (vertical) and (b) series of pulses of intense jetting where every pulse lasts about 20s and starts with vertical velocities up to 85 m/s (measured ~75m above vent). Our deployment at Colima volcano is the first investigation of Vulcanian eruption column dynamics using Doppler radar. The data provide particle velocities and a proxy of the particles mass ~75m above the vent, which allows us to define the activity status in near real time during an eruption. Here we focus on the dynamic processes during the early stages of eruption cloud formation. Using (1) a simple ballistic model for particle transport and (2) the active tracer high-resolution atmospheric model (ATHAM) we model the first 100 m of cloud formation in 2D (axis-symmetric) and 3D. We constrain the initial conditions for both models trying to reproduce the dynamics measured by the radars. For this comparison synthetic Doppler radar data are calculated from the numerical models by converting particle properties (size, velocity, and backscatter-efficiency) into synthetic velocity spectra. First results show that pure ballistic transport of particles in a gas jet cannot reproduce the measured spectra. Eruption clouds are a major hazard to aviation. Hence real-time tracking and forecasting of ash clouds are increasingly important tasks in volcanology. In-situ measurements of the dynamics inside the developing cloud are needed to constrain the input parameters of the Volcanic Ash Advisory Center's (VAAC) numerical ash cloud dispersion models. Our aim is to directly deduce the initial conditions for an eruption column model or ash dispersal model from the radar data in near-real time.

Scharff, L.; Hort, M. K.; Varley, N. R.; Herzog, M.

2011-12-01

299

Characterization of Mesoscale Convective Systems by Means of Composite Radar Reflectivity Data  

NASA Technical Reports Server (NTRS)

A mesoscale convective system (MCS) is broadly defined as a cloud and precipitation system of mesoscale dimensions (often too large for most aircraft to circumnavigate) with deep-convective activity concentrated in at least part of the MCS, or present during part of its evolution. A large areal fraction of MCSs is stratiform in nature, yet estimates from MCSs over the Great Plains, the Southeast, and tropical waters indicate that at least half of the precipitation is of convective origin. The presence of localized convection is important, because within convective towers cloud particles and hydrometeors are carried upward towards the cloud top. Ice crystals then move over more stratiform regions, either laterally, or through in situ settling over decaying and spreading convection. These ice crystals then grow to precipitation-size particles in mid- to upper tropospheric mesoscale updrafts. The convective portion of a MCS is often a more or less continuous line of thunderstorms, and may be either short-lived or long-lived. Geerts (1997) presents a preliminary climatology of MCSs in the southeastern USA, using just one year of composite digital radar reflectivity data. In this study MCSs are identified and characterized by means of visual inspection of animated images. A total of 398 MCSs were identified. In the warm season MCSs were found to be about twice as frequent as in the cold season. The average lifetime and maximum length of MCSs are 9 hours, and 350 km, respectively, but some MCSs are much larger and more persistent. In the summer months small and short-lived MCSs are relatively more common, whereas in winter larger and longer-lived systems occur more frequently. MCSs occur more commonly in the afternoon, in phase with thunderstorm activity, but the amplitude of the diurnal cycle is small compared to that of observed thunderstorms. It is estimated that in the Southeast more than half of all precipitation and severe weather results from MCSs.

Geerts, Bart

1998-01-01

300

Use of the X-Band Radar to Support the Detection of In-Flight Icing Hazards by the NASA Icing Remote Sensing System  

NASA Technical Reports Server (NTRS)

The Alliance Icing Research Study-II (AIRS-II) field program was conducted near Montreal, Canada during the winter of 2003. The NASA Icing Remote Detection System (NIRSS) was deployed to detect in-flight icing hazards and consisted of a vertically pointing multichannel radiometer, a ceilometer and an x-band cloud radar. The radiometer was used to derive atmospheric temperature soundings and integrated liquid water, while the ceilometer and radar were used only to define cloud boundaries. The purpose of this study is to show that the radar reflectivity profiles from AIRS-II case studies could be used to provide a qualitative icing hazard.

Serke, David J.; Politovich, Marcia K.; Reehorst, Andrew L.; Gaydos, Andrew

2009-01-01

301

Adaptive phased array radar processing on a multi-channel, acousto-optic, linear algebra system - Experimental results  

NASA Astrophysics Data System (ADS)

The use of a high accuracy optical processor to obtain the optimal solution for the weight vector in the adaptive phased array radar (APAR) problem is discussed. This optical system is a multichannel, acoustooptic architecture which obtains high accuracy results through the encoding of the numerical data as bit stream which are processed optically. The actual accuracy is based upon the number of bits used for processing and is controlled through software. Experimental results obtained using the laboratory optical processing system are presented for several APAR signal environments. These experiments demonstrate that the optical processing system is capable of yielding weight vectors nearly identical to the optimal solution.

Carroll, C. W.; Kumar, B. V. K. Vijaya

1988-01-01

302

Remote profiling of lake ice thickness using a short pulse radar system aboard a C-47 aircraft  

NASA Technical Reports Server (NTRS)

Description of the design and operation of two new short-pulse radar systems developed for use aboard aircraft for remote profiling of lake ice thickness. The principle of operation is based on the fact that the return signal is composed of a pulse return from the top of the ice and another, delayed in time, from the ice-water interface. The delay time between these two pulses directly gives the ice thickness when allowance is made for the slower RF propagation through the ice. The two systems are the S band and the C band systems, and their comparative merits are discussed.

Cooper, D. W.; Heighway, J. E.; Shook, D. F.; Jirberg, R. J.; Vickers, R. S.

1974-01-01

303

Cyclostationary Approach for Heart and Respiration Rates Monitoring with Body Movement Cancellation Using Radar Doppler System  

E-print Network

Heart and respiration rate measurement using Doppler radar is a non-contact and non-obstructive way for remote thorough-clothing monitoring of vital signs. The modulated back-scattered radar signal in the presence of high noise and interference is non-stationary with hidden periodicities, which cannot be detected by ordinary Fourier analysis. In this paper we propose a cyclostationary approach for such signals and show that by using non-linear transformation and then Fourier analysis of the radar signal, the hidden periodicities can be accurately obtained. Numerical results show that the vital signs can be extracted as cyclic frequencies, independent of SNR and without any filtering or phase unwrapping.

Kazemi, Somayeh; Amindavar, Hamidreza; Li, Changzhi

2013-01-01

304

Assimilation of Doppler Radar Observations with a Regional 3DVAR System: Impact of Doppler Velocities on Forecasts of a Heavy Rainfall Case  

Microsoft Academic Search

In this paper, the impact of Doppler radar radial velocity on the prediction of a heavy rainfall event is examined. The three-dimensional variational data assimilation (3DVAR) system for use with the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5) is further developed to enable the assimilation of radial velocity observations. Doppler velocities from the Korean Jindo radar are assimilated into MM5

Qingnong Xiao; Ying-Hwa Kuo; Juanzhen Sun; Wen-Chau Lee; Eunha Lim; Yong-Run Guo; Dale M. Barker

2005-01-01

305

78 FR 68861 - Certain Navigation Products, Including GPS Devices, Navigation and Display Systems, Radar Systems...  

Federal Register 2010, 2011, 2012, 2013

...Navigational Aids, Mapping Systems and Related Software; Institution of Investigation Pursuant...navigational aids, mapping systems and related software by reason of infringement of certain...navigational aids, mapping systems and related software by reason of infringement of one or...

2013-11-15

306

Research relative to weather radar measurement techniques  

NASA Technical Reports Server (NTRS)

This grant provides for some investigations related to weather radar measurement techniques applicable to meteorological radar systems in Thailand. Quality data are needed from those systems to support TRMM and other scientific investigations. Activities carried out during a trip to the radar facilities at Phuket are described.

Smith, Paul L.

1992-01-01

307

Generalized radar/radiometry imaging problems  

E-print Network

- ing simulation based on radar, synthetic aperture radar (SAR) and radiometry systems are presented of real time image processing. Thus, the problem of adequate simulation of image formation actual. In this paper three main classes of imaging systems (mono- static radar, SAR and radiometer

Genève, Université de

308

On wave radar measurement  

NASA Astrophysics Data System (ADS)

The SAAB REX WaveRadar sensor is widely used for platform-based wave measurement systems by the offshore oil and gas industry. It offers in situ surface elevation wave measurements at relatively low operational costs. Furthermore, there is adequate flexibility in sampling rates, allowing in principle sampling frequencies from 1 to 10 Hz, but with an angular microwave beam width of 10° and an implied ocean surface footprint in the order of metres, significant limitations on the spatial and temporal resolution might be expected. Indeed there are reports that the accuracy of the measurements from wave radars may not be as good as expected. We review the functionality of a WaveRadar using numerical simulations to better understand how WaveRadar estimates compare with known surface elevations. In addition, we review recent field measurements made with a WaveRadar set at the maximum sampling frequency, in the light of the expected functionality and the numerical simulations, and we include inter-comparisons between SAAB radars and buoy measurements for locations in the North Sea.

Ewans, Kevin; Feld, Graham; Jonathan, Philip

2014-09-01

309

Cognitive processing for nonlinear radar  

NASA Astrophysics Data System (ADS)

An increasingly cluttered electromagnetic environment (EME) is a growing problem for radar systems. This problem is becoming critical as the available frequency spectrum shrinks due to growing wireless communication device usage and changing regulations. A possible solution to these problems is cognitive radar, where the cognitive radar learns from the environment and intelligently modifies the transmit waveform. In this paper, a cognitive nonlinear radar processing framework is introduced where the main components of this framework consist of spectrum sensing processing, target detection and classification, and decision making. The emphasis of this paper is to introduce a spectrum sensing processing technique that identifies a transmit-receive frequency pair for nonlinear radar. It will be shown that the proposed technique successfully identifies a transmit-receive frequency pair for nonlinear radar from data collected from the EME.

Martone, Anthony; Ranney, Kenneth; Hedden, Abigail; Mazzaro, Gregory; McNamara, David

2013-05-01

310

Australian Weather Watch Radar Home Page  

NSDL National Science Digital Library

The Commonwealth Bureau of Meteorology's Weather Watch Radar website provides up-to-date radar images of the locations of rain in Australia in relation to local features such as coast lines. The newly developed Loops provide four consecutive radar images so that users can view how the weather has been changing in the last forty to fifty minutes. The website provides radar images of past cyclone events as well as updates on severe weather throughout Australia. Those interested in radar systems can discover how the weather radars work and how to interpret the maps. [RME

311

3D AOA\\/TDOA emitter location by integrated passive radar\\/GPS\\/INS systems  

Microsoft Academic Search

3D passive geolocation of radar emitters is an important problem in electronic support for military surveillance. The angle of arrivals (AOA) and time difference of arrivals (TDOA) are two popular schemes for passive emitter location. In this paper, a location scheme is proposed based on fusion of AOA and TDOA measurements from two electronic support measures (ESM) sensors installed on

Wenhua Li; Peiguo Liu

2005-01-01

312

Development of micropower ultrawideband impulse radar medical diagnostic systems for continuous monitoring applications and austere environments  

Microsoft Academic Search

This paper discusses the application of Micropower Ultrawideband Impulse Radar (MUIR) technology to the detection and monitoring of intracranial hemorrhage. MUIR is ideally suited for medical diagnostic and monitoring applications because the emitted electromagnetic radiation is non-ionizing and has both peak and average power levels that are orders of magnitude lower than those of a hand-held cell phone. Furthermore, MUIR

John Chang; Christine Paulson; Patrick Welsh

2012-01-01

313

Automatic ship classification system for inverse synthetic aperture radar (ISAR) imagery  

Microsoft Academic Search

The U.S. Navy has been interested in applying neural network processing architectures to automatically determine the naval class of ships from an inverse synthetic aperture radar (ISAR) on-board an airborne surveillance platform. Currently an operator identifies the target based on an ISAR display. The emergence of the littoral warfare scenario, coupled with the addition of multiple sensors on the platform,

Murali M. Menon

1995-01-01

314

Multi-frequency synthetic-aperture imaging with a lightweight ground penetrating radar system  

Microsoft Academic Search

The detection of buried objects, particularly hazardous waste containers and unexploded ordnance (UXO), has gained significant interest in the Unites States in the late 1990s. The desire to remediate the thousands of sites worldwide has become an increasing concern and the application of radar to this problem has received renewed attention. The US Department of Energy's Special Technologies Laboratory (STL),

Steven K. Koppenjan; Curt M. Allen; Duane Gardner; Howard R. Wong; Hua Lee; Stephanie J. Lockwood

2000-01-01

315

76 FR 35176 - Operation of Radar Systems in the 76-77 GHz Band  

Federal Register 2010, 2011, 2012, 2013

...Office of Engineering and Technology, 445 12th Street, SW...enable enhanced vehicular radar technologies in the 76-77 GHz band...to impose requirements for a GPS-aware automatic cut-off...cable television equipment, GPS equipment, pagers,...

2011-06-16

316

Development of a GPS-aided motion measurement, pointing, and stabilization system for a Synthetic Aperture Radar. [Global Positioning System (GPS)  

SciTech Connect

An advanced Synthetic Aperture Radar Motion Compensation System has been developed by Sandia National Laboratories (SNL). The system includes a miniaturized high accuracy ring laser gyro inertial measurement unit, a three axis gimbal pointing and stabilization assembly, a differential Global Positioning System (GPS) navigation aiding system, and a pilot guidance system. The system provides several improvements over previous SNL motion compensation systems and is capable of antenna stabilization to less than 0.01 degrees RMS and absolute position measurement to less than 5.0 meters RMS. These accuracies have been demonstrated in recent flight testing aboard a DHC-6-300 Twin Otter'' aircraft.

Fellerhoff, J.R.; Kohler, S.M.

1991-01-01

317

Radar sector blanker  

NASA Astrophysics Data System (ADS)

A radar sector blanker comprises in analog-to-digital converter and a sector controller unit. The analog-to-digital converter receives the analog synchro voltages describing the positioning of a radar antenna and changes these voltages into binary-coded decimal (BCD) information. The sector controller unit comprises a portable housing, a controller system, and a power supply. The controller system includes an OFF comparator circuit, an ON comparator circuit, an S-R latch, and a solid-state switch. Each comparator circuit comprises three cascaded transistor-transistor logic (TTL) integrated chips. The power supply gives a direct-current voltage to the solid-state switch and the TTL chips. The sector blanker blocks transmission for a predetermined rotational region or sector of a radar system.

Hall, Roger B.

1994-03-01

318

First Results Of The New Goldstone Delay-Doppler Radar Chirp Imaging System  

NASA Astrophysics Data System (ADS)

We report the first results of a new delay-Doppler radar chirp waveform system at Goldstone, which improves the range resolution by a factor of five from 18.75-m to 3.75-m. We successfully tested the new system on near-Earth asteroids (NEAs) 2010 AL30 and 2009 UN3 in January and February 2010. 2010 AL30 was a target-of-opportunity observed only three days after its discovery by LINEAR on January 10. During 2.3 hours of observations, 2010 AL30 moved between 1.0 to 0.8 lunar distances from Earth en route to a close approach of only 0.34 lunar distances. Due to this short round-trip light-travel time, the observations were bistatic with transmissions at the 70-m DSS-14 antenna and reception at the 34-m DSS-13 antenna. 2010 AL30 has a very faint absolute magnitude of 27.2, suggesting a diameter of less than 20 meters. We imaged 2010 AL30 at resolutions as high as 3.75-m, which reveal a somewhat elongated shape roughly 15-m in diameter, making 2010 AL30 the smallest NEA spatially resolved at Goldstone to date. The sequence of images shows obvious rotation that is consistent with the period of about 9 minutes reported by W. Ryan. (pers. comm.). 2009 UN3 was discovered in October 2009 by the Siding Spring Survey and approached within 0.037 AU (14 lunar distances) on February 9. We observed 2009 UN3 monostatically at Goldstone on February 8 and 9. Due to its moderate SNRs, we used chirp imaging at 15-m and 30-m resolutions, and binary-phase-coded imaging with 37.5-m resolution. The images reveal an irregular, elongated object close to 700-m in diameter. For future research, the new 3.75-m-resolution capability at Goldstone offers significant scientific potential to reveal much more detailed surface features than previously possible, to yield more detailed 3D shapes, and to substantially improve NEA orbits and long-term orbit prediction.

Slade, Martin A.; Lee, C. G.; Jao, J. S.; Benner, L. A. M.; Brozovic, M.; Giorgini, J. D.; Busch, M. W.

2010-10-01

319

Remote profiling of lake ice thickness using a short pulse radar system aboard a C-47 aircraft  

NASA Technical Reports Server (NTRS)

Design and operation of short pulse radar systems for use in ice thickness measurement are described. Two ice profiling systems were tested, an S system which used either random noise or continous wave modulation at 2.8 GHz and a less powerful C band system which operated at 6.0 GHz and did not have random noise modulation. Flight altitudes of 4,000 feet were used, but the S band system was usable at 7,000 feet allowing flights in poor weather conditions. A minimum ice thickness of four inches is required for measurement, while the thickest ice measured was 36 inches. System accuracy is plus or minus one inch.

Cooper, D. W.; Heighway, J. E.; Shook, D. F.; Jirberg, R. J.; Vickers, R. S.

1974-01-01

320

Space-based radar. II - An overview  

NASA Astrophysics Data System (ADS)

The paper examines the major functions a pulse Doppler space-based radar system will be required to perform, including search, track, target classification, and designation for strike. In addition, attention is given to orbital considerations, such phenomenological factors as clutter statistics and target characteristics, radar technology, and the radar in the overall spacecraft design.

Avrin, J.

1981-10-01

321

Space-based radar clutter cancellation techniques  

Microsoft Academic Search

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent upon the clutter cancellation technique employed. In this paper, radar clutter is described using temporal probability models, spectral models, and average backscatter coefficient models. Capitalizing on the different spectral characteristics between clutter and targets, three representative Doppler clutter cancellation

J. Devenuto; K. G. Castor

1984-01-01

322

Implications of modeling clutter for radar simulations  

NASA Astrophysics Data System (ADS)

Methods for minimizing clutter returns which enhance the performance of surveillance radar systems are discussed. Included are methods which were implemented in the radar simulations currently in use at the Rome Air Development Center. The simulation output will include plots of raw clutter data for different mediums and clutter-to-noise ratios established after signal processing by a radar receiver.

Borek, Stanley E.; Pechewlys, Deborah A.

323

Millimeter-Wave Concurrent Dual-Band BiCMOS RFIC Transmitter for Radar and Communication Systems  

E-print Network

in radio astronomy and synthetic aperture radar (SAR) applications [14]. Receiver The radar receivers amplify, filter, and down-convert the received signal to the intermediate frequency (IF) or baseband signal, from which the target can be correctly... in radio astronomy and synthetic aperture radar (SAR) applications [14]. Receiver The radar receivers amplify, filter, and down-convert the received signal to the intermediate frequency (IF) or baseband signal, from which the target can be correctly...

Huynh, Cuong Phu Minh 1976-

2012-11-21

324

Spaceborne radar remote sensing: Applications and techniques  

Microsoft Academic Search

The operation and applications of spaceborne radars for terrestrial and planetary remote sensing are described in an introduction for advanced students and practicing scientists. Chapters are devoted to imaging radars, wave-surface interactions and geoscientific applications, real- and synthetic-aperture radars, end-to-end system design, SAR data processing, altimeters, and scatterometers. Extensive diagrams, drawings, graphs, photographs, and sample radar images are provided.

Charles Elachi

1988-01-01

325

A highly capable arbitrary waveform generator for next generation radar systems  

NASA Technical Reports Server (NTRS)

We are developing an Arbitrary Waveform Generator (AWG) to provide enhanced capability for radar applications. The current design will accommodate two waveform generators on a single unit for dual frequency operation. The basic architecture of this unit employs a Field Programmable Gate Array (FPGA) and a high speed and high precision Digital to Analog Converter (DAC) for direct digital synthesis. This AWG will be capable of up to 450 MHz bandwidth with ability for frequency notching. Phase fidelity of less than 1.2(sup o) deviation RMS is also achievable. This AWG operates with lower power consumption as compared with other waveform generators, which is advantageous for future spaceborne applications. This will enable radars to return higher precision data, to be reduced in complexity, and to operate in any band without interfering with dedicated bandwidths.

Chuang, Ernie; Hensley, Scott; Wheeler, Kevin

2006-01-01

326

A short-term predictive system for surface currents from a rapidly deployed coastal HF radar network  

NASA Astrophysics Data System (ADS)

In order to address the need for surface trajectory forecasts following deployment of coastal HF radar systems during emergency-response situations (e.g., search and rescue, oil spill), a short-term predictive system (STPS) based on only a few hours data background is presented. First, open-modal analysis (OMA) coefficients are fitted to 1-D surface currents from all available radar stations at each time interval. OMA has the effect of applying a spatial low-pass filter to the data, fills gaps, and can extend coverage to areas where radial vectors are available from a single radar only. Then, a set of temporal modes is fitted to the time series of OMA coefficients, typically over a short 12-h trailing period. These modes include tidal and inertial harmonics, as well as constant and linear trends. This temporal model is the STPS basis for producing up to a 12-h current vector forecast from which a trajectory forecast can be derived. We show results of this method applied to data gathered during the September 2010 rapid-response demonstration in northern Norway. Forecasted coefficients, currents, and trajectories are compared with the same measured quantities, and statistics of skill are assessed employing 16 24-h data sets. Forecasted and measured kinetic variances of the OMA coefficients typically agreed to within 10-15%. In one case where errors were larger, strong wind changes are suspected and examined as the cause. Sudden wind variability is not included properly within the STPS attack we presently employ and will be a subject for future improvement.

Barrick, Donald; Fernandez, Vicente; Ferrer, Maria I.; Whelan, Chad; Breivik, Øyvind

2012-05-01

327

Regional and Diurnal Variability of the Vertical Structure of Precipitation Systems in Africa Based on Spaceborne Radar Data  

E-print Network

). Large differences exist between passive microwave and radar-based rain-rate estimates, mainly Rainfall Measuring Mission (TRMM) 2A25 radar reflectivity profiles and derived surface rain rates are used on Spaceborne Radar Data BART GEERTS AND TEFERI DEJENE Department of Atmospheric Science, University of Wyoming

Geerts, Bart

328

The Weather Radar Toolkit, National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center's support of interoperability and the Global Earth Observation System of Systems (GEOSS)  

NASA Astrophysics Data System (ADS)

In February 2005, 61 countries around the World agreed on a 10 year plan to work towards building open systems for sharing geospatial data and services across different platforms worldwide. This system is known as the Global Earth Observation System of Systems (GEOSS). The objective of GEOSS focuses on easy access to environmental data and interoperability across different systems allowing participating countries to measure the "pulse" of the planet in an effort to advance society. In support of GEOSS goals, NOAA's National Climatic Data Center (NCDC) has developed radar visualization and data exporter tools in an open systems environment. The NCDC Weather Radar Toolkit (WRT) loads Weather Surveillance Radar 1988 Doppler (WSR-88D) volume scan (S-band) data, known as Level-II, and derived products, known as Level-III, into an Open Geospatial Consortium (OGC) compliant environment. The application is written entirely in Java and will run on any Java- supported platform including Windows, Macintosh and Linux/Unix. The application is launched via Java Web Start and runs on the client machine while accessing these data locally or remotely from the NCDC archive, NOAA FTP server or any URL or THREDDS Data Server. The WRT allows the data to be manipulated to create custom mosaics, composites and precipitation estimates. The WRT Viewer provides tools for custom data overlays, Web Map Service backgrounds, animations and basic filtering. The export of images and movies is provided in multiple formats. The WRT Data Exporter allows for data export in both vector polygon (Shapefile, Well-Known Text) and raster (GeoTIFF, ESRI Grid, VTK, NetCDF, GrADS) formats. By decoding the various Radar formats into the NetCDF Common Data Model, the exported NetCDF data becomes interoperable with existing software packages including THREDDS Data Server and the Integrated Data Viewer (IDV). The NCDC recently partnered with NOAA's National Severe Storms Lab (NSSL) to decode Sigmet C-band Doppler radar data providing the NCDC Viewer/Data Exporter the functionality to read C-Band. This also supports a bilateral agreement between the United States and Canada for data sharing and to support interoperability with the US WSR-88D and Environment Canada radar networks. In addition, the NCDC partnered with the University of Oklahoma to develop decoders to read a test bed of distributed X- band radars that are funded through the Collaborative Adaptive Sensing of the Atmosphere (CASA) project. The NCDC is also archiving the National Mosaic and Next Generation QPE (Q2) products from NSSL, which provide products such as three-dimensional reflectivity, composite reflectivity and precipitation estimates at a 1 km resolution. These three sources of Radar data are also supported in the WRT.

Ansari, S.; Del Greco, S.

2006-12-01

329

Use of ground-penetrating radar technology in construction of the Los Angeles MetroRail subway system  

NASA Astrophysics Data System (ADS)

State-of-the-art ground penetrating radar (GPR) technology was used successfully in tunneling through the former L.A. City Oil Field to search for uncharted, abandoned oil wells. A magnetometer probe was previously used for this purpose, because it was felt abandoned oil wells with steel casings may exist ahead of tunneling. These wells were suspected to contain methane gases which could be released into the tunnels. Studies revealed the abandoned wells could be wooden-cased or uncased open holes, indicating they would not be detected using a magnetometer probe. GPR was therefore selected as a geophysical technique more capable of detecting both steel-cased and uncased oil wells. After some initial testing from inside the tunnel, a commercially available GPR system was selected. Procedures were developed for conducting the surveys and evaluating the data profiles for possible oil wells. The profiles were obtained by moving the radar antenna across the smoothed tunnel face. During tunnelling of the oil field area abandoned oil wells were not encountered. However, the GPR surveys did detect anomalous radar reflections that the machine operator was alerted to as possible oil wells. Review of the data indicates that other changes in ground conditions were detected, such as transitions from soft- to hard-ground conditions and zones of oil bearing sands. These results suggest GPR could be useful for other exploratory applications during mining. GPR was also used as an investigative tool to check for possible shallow subsurface voids from the ground surface. Air-filled cavities or voids beneath city streets can sometimes be formed as a result of deeper tunneling-induced ground movements, resulting in dangerous sink-hole forming conditions. The GPR surveys were conducted from the street surface above the tunnels in areas where geotechnical data measured greater ground movements. These surveys helped rule out the possibility of voids beneath the street pavement in an area where over nine inches of ground settlement was measured.

Hebert, Christopher D.; Olson, Mark G.

1995-05-01

330

Airborne Doppler radar for wind shear detection  

NASA Technical Reports Server (NTRS)

There has been extensive discussion concerning the use of ground based Doppler radars for the detection and measurement of microburst features and the mapping of associated wind shears. Recent and planned research at Langley into technology and techniques useful for the future development of airborne Doppler weather radar systems for both turbulence and wind shear detection are addressed. Such systems, if successfully developed, would represent a marked increase in performance over airborne weather radars currently available. A principal difficulty in extending to airborne radars the capabilities of current ground based Doppler radars is emphasized.

Staton, Leo

1987-01-01

331

Multinomial pattern matching for high range resolution radar profiles  

NASA Astrophysics Data System (ADS)

Airborne ground moving-target indication (GMTI) radar can track moving vehicles at large standoff distances. Unfortunately, trajectories from multiple vehicles can become kinematically ambiguous, resulting in confusion between a target vehicle of interest and other vehicles. We propose the use of high range resolution (HRR) radar profiles and multinomial pattern matching (MPM) for target fingerprinting and track stitching to overcome kinematic ambiguities. Sandia's MPM algorithm is a robust template-based identification algorithm that has been applied successfully to various target recognition problems. MPM utilizes a quantile transformation to map target intensity samples to a small number of grayscale values, or quantiles. The algorithm relies on a statistical characterization of the multinomial distribution of the sample-by-sample intensity values for target profiles. The quantile transformation and statistical characterization procedures are extremely well suited to a robust representation of targets for HRR profiles: they are invariant to sensor calibration, robust to target signature variations, and lend themselves to efficient matching algorithms. In typical HRR tracking applications, target fingerprints must be initiated on the fly from a limited number of HRR profiles. Data may accumulate indefinitely as vehicles are tracked, and their templates must be continually updated without becoming unbounded in size or complexity. To address this need, an incrementally updated version of MPM has been developed. This implementation of MPM incorporates individual HRR profiles as they become available, and fuses data from multiple aspect angles for a given target to aid in track stitching. This paper provides a description of the incrementally updated version of MPM.

Koudelka, Melissa L.; Richards, John A.; Koch, Mark W.

2007-04-01

332

Characteristics of Sunset radar  

NASA Technical Reports Server (NTRS)

Located in a narrow canyon 15 km west of Boulder, Colorado, the Sunset pulsed Doppler radar was the first radar designed and constructed specifically as a VHF ST radar. The antenna system is a phased array of coaxial-colinear dopoles with computer-controlled phase shifters for each line of dipoles. It operates at a frequency of 40.475 MHz and a wavelength of 7.41M. Peak transmitter power is 100 kW. Aperture efficiency is 0.58 and resistive loss is 0.30 for its 3600 sq m area. The practical steering rate is 1 record/minute/position to any arbitrary antenna beam position. The first clear-air turbulence echoes and wind velocity measurements were obtained in 1974. Significant accomplishments are listed.

Green, J. L.

1983-01-01

333

Real time control of a combined sewer system using radar-measured precipitation--results of the pilot study.  

PubMed

Emschergenossenschaft and Lippeverband have developed a method to use radar-measured precipitation as an input for a real-time control of a combined sewer system containing several overflow structures. Two real-time control strategies have been developed and tested, one is solely volume-based, the other is volume and pollution-based. The system has been implemented in a pilot study in Gelsenkirchen, Germany. During the project the system was optimised and is now in constant operation. It was found, that the volume of combined sewage overflow could be reduced by 5 per cent per year. This was also found in simulations carried out in similar catchment areas. Most of the potential of improvement can already be achieved by local pollution-based control strategies. PMID:12793702

Petruck, A; Holtmeier, E; Redder, A; Teichgräber, B

2003-01-01

334

Signature management of radar returns from wind turbine generators  

Microsoft Academic Search

The large radar cross section of wind turbine generator (WTG) blades combined with high tip speeds can produce significant Doppler returns when illuminated by a radar. Normally, an air traffic control radar system will filter out large returns from stationary targets, but the Doppler shifts introduced by the WTG blades are interpreted as moving aircraft that can confuse radar operators

A. Tennant; B. Chambers

2006-01-01

335

Paleodrainages of the Eastern Sahara - The radar rivers revisited (SIR-A/B implications for a mid-tertiary Trans-African drainage system)  

NASA Technical Reports Server (NTRS)

The images obtained by the Shuttle Imaging Radar (SIR)-A and -B systems over the southwestern Egypt and northwestern Sudan were coregistered with the Landsat images and the existing maps to aid in extrapolations of the buried paleodrainages ('radar rivers'), first discovered by SIR-A. Field observations explain the radar responses of three types of radar rivers, RR-1 (broad, aggraded valleys filled with alluvium), RR-2 (braided channels inset in the RR-1 valleys), and RR-3 (narrow, long, bedrock-incised channels). A generalized model of the radar rivers, based on field studies and regional geologic relations, shows inferred changes in river regimen since the large valleys were established during the later Paleogene-early Neogene. It is suggested that a former Trans-African master stream system may have flowed from headwaters in the Red Sea Hills southwestward across North Africa, discharging into the Atlantic at the Paleo-Niger delta, prior to the Neogene domal uplifts and building of volcanic edifices across the paths of these ancient watercourses.

Mccauley, J. F.; Breed, C. S.; Schaber, G. G.; Mchugh, W. P.; Haynes, C. C.

1986-01-01

336

A radar image time series  

NASA Technical Reports Server (NTRS)

A set of ten side-looking radar images of a mining area in Arizona that were aquired over a period of 14 yr are studied to demonstrate the photogrammetric differential-rectification technique applied to radar images and to examine changes that occurred in the area over time. Five of the images are rectified by using ground control points and a digital height model taken from a map. Residual coordinate errors in ground control are reduced from several hundred meters in all cases to + or - 19 to 70 m. The contents of the radar images are compared with a Landsat image and with aerial photographs. Effects of radar system parameters on radar images are briefly reviewed.

Leberl, F.; Fuchs, H.; Ford, J. P.

1981-01-01

337

The Newcastle meteor radar  

NASA Technical Reports Server (NTRS)

A brief history and development of the Newcastle Meteor Radar system is given. Also described are its geographical coordinates and its method of operation. The initial objective when the project was commenced was to develop an entirely digital analyzer capable of recognizing meteor echo signals and recording as many of their parameters as possible. This objective was achieved.

Keay, Colin

1987-01-01

338

Shuttle orbiter Ku-band radar/communications system design evaluation: High gain antenna/widebeam horn  

NASA Technical Reports Server (NTRS)

The physical characteristics of the high gain antenna reflector and feed elements are described. Deficiencies in the sum feed are discussed, and lack of atmospheric venting is posed as a potential problem area. The measured RF performance of the high gain antenna is examined and the high sidelobe levels measured are related to the physical characteristics of the antenna. An examination of the attributes of the feed which might be influenced by temperature extremes shows that the antenna should be insensitive to temperature variations. Because the feed support bipod structure is considered a significant contributor to the high sidelobe levels measured in the azimuth plane, pod relocation, material changes, and shaping are suggested as improvements. Alternate feed designs are presented to further improve system performance. The widebeam horn and potential temperature effects due to the polarizer are discussed as well as in the effects of linear polarization on TDRS acquisition, and the effects of circular polarization on radar sidelobe avoidance. The radar detection probability is analyzed as a function of scan overlap and target range.

Iwasaki, R.; Dodds, J. G.; Broad, P.

1979-01-01

339

Dual Super-Systolic Core for Real-Time Reconstructive Algorithms of High-Resolution Radar/SAR Imaging Systems  

PubMed Central

A high-speed dual super-systolic core for reconstructive signal processing (SP) operations consists of a double parallel systolic array (SA) machine in which each processing element of the array is also conceptualized as another SA in a bit-level fashion. In this study, we addressed the design of a high-speed dual super-systolic array (SSA) core for the enhancement/reconstruction of remote sensing (RS) imaging of radar/synthetic aperture radar (SAR) sensor systems. The selected reconstructive SP algorithms are efficiently transformed in their parallel representation and then, they are mapped into an efficient high performance embedded computing (HPEC) architecture in reconfigurable Xilinx field programmable gate array (FPGA) platforms. As an implementation test case, the proposed approach was aggregated in a HW/SW co-design scheme in order to solve the nonlinear ill-posed inverse problem of nonparametric estimation of the power spatial spectrum pattern (SSP) from a remotely sensed scene. We show how such dual SSA core, drastically reduces the computational load of complex RS regularization techniques achieving the required real-time operational mode. PMID:22736964

Atoche, Alejandro Castillo; Castillo, Javier Vazquez

2012-01-01

340

Using X-band Weather Radar Measurements to Monitor the Integrity of Digital Elevation Models for Synthetic Vision Systems  

NASA Technical Reports Server (NTRS)

Synthetic Vision Systems (SVS) provide pilots with displays of stored geo-spatial data representing terrain, obstacles, and cultural features. As comprehensive validation is impractical, these databases typically have no quantifiable level of integrity. Further, updates to the databases may not be provided as changes occur. These issues limit the certification level and constrain the operational context of SVS for civil aviation. Previous work demonstrated the feasibility of using a realtime monitor to bound the integrity of Digital Elevation Models (DEMs) by using radar altimeter measurements during flight. This paper describes an extension of this concept to include X-band Weather Radar (WxR) measurements. This enables the monitor to detect additional classes of DEM errors and to reduce the exposure time associated with integrity threats. Feature extraction techniques are used along with a statistical assessment of similarity measures between the sensed and stored features that are detected. Recent flight-testing in the area around the Juneau, Alaska Airport (JNU) has resulted in a comprehensive set of sensor data that is being used to assess the feasibility of the proposed monitor technology. Initial results of this assessment are presented.

Young, Steve; UijtdeHaag, Maarten; Sayre, Jonathon

2003-01-01

341

A Numerical Model for VHF Meteor Radars  

Microsoft Academic Search

VHF meteor radar systems are employed in various locations around the earth to measure the wind speeds and directions in the Mesosphere and Lower Thermosphere (MLT) region. The design of these radar systems is highly driven by existing systems and earlier system success rather than detailed system simulation. We will present our current work and results from an effort to

Kyle Johnson; Scott Palo; Diego Janches; Jonathan Fentzke

2008-01-01

342

Research relative to weather radar measurement techniques  

NASA Technical Reports Server (NTRS)

Research relative to weather radar measurement techniques, which involves some investigations related to measurement techniques applicable to meteorological radar systems in Thailand, is reported. A major part of the activity was devoted to instruction and discussion with Thai radar engineers, technicians, and meteorologists concerning the basic principles of radar meteorology and applications to specific problems, including measurement of rainfall and detection of wind shear/microburst hazards. Weather radar calibration techniques were also considered during this project. Most of the activity took place during two visits to Thailand, in December 1990 and February 1992.

Smith, Paul L.

1992-01-01

343

Mars Radar Opens a Planet's Third Dimension  

NASA Technical Reports Server (NTRS)

Radar sounder instruments orbiting Mars have looked beneath the Martian surface and opened up the third dimension for planetary exploration. The technique's success is prompting scientists to think of all the other places in the Solar System where they would like to use radar sounders.

The first radar sounder at Mars was the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on the European Space Agency's Mars Express Orbiter. It has been joined by the complementary Shallow Subsurface Radar (SHARAD), operating at a different wavelength aboard NASA's Mars Reconnaissance Orbiter. The data in this animation are from SHARAD.

2008-01-01

344

NASA Radar Images Asteroid Toutatis  

NASA Video Gallery

This 64-frame movie of asteroid Toutatis was generated from data by Goldstone's Solar System Radar on Dec. 12 and 13, 2012. In the movie clips, the rotation of the asteroid appears faster than it o...

345

Fabrication of Radar Absorbing Shells Made of Hybrid Composites and Evaluation of Radar Cross Section  

Microsoft Academic Search

** , Seoung-Bae Park ** and Myung-Shik Won *** ABSTRACT The avoidance of enemy's radar detection is very important issue in the modern electronic weapon system. Researchers have been studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), \\

Woo-Kyun Jung; Sung-Hoon Ahn; Bierng-Chearl Ahn

2005-01-01

346

Radar cross-section analysis of wind turbine blades with radar absorbing materials  

Microsoft Academic Search

Wind turbines interfere with radar systems due to their large radar cross-section (RCS) and the rotation of the blades. Applying radar absorbing materials (RAM) is considered as a possible mitigation measure. This paper will present RCS modeling results of a generic 40 meters blade. The blade is segmented into 4 sections and the monostatic scattering from each section is modeled.

L. S. Rashid; A. K Brown

2011-01-01

347

An investigation of 3.2-cm attenuation by subtropical precipitation through use of a dual-frequency, equi-volume radar system  

E-print Network

17 17 Average attenuation The reflectivity factor (Z) Attenuation at a point ~ ~ 17 21 26 iv Chapter IV. DATA COLLECTION Collection of Basic Data Systems Chosen for Analysis V. RESULTS AND ERROR ANALYSIS The Radar Constant Discrepancy... the 10. 3-cm wave-length radar viii PA PS PT pTO &A &s &TO S 0 td VT Wl Ze e the ' indicates P* value actually observed (cm ) total absorbed power total scattered power transmitted power (kw) total power removed from the beam total...

Hodges, Donald Bartholomew

2012-06-07

348

Adaptive optics for large aperture coherent laser radars  

Microsoft Academic Search

When the aperture size of a coherent laser radar is much larger than the turbulence coherence length, the radar's performance is significantly degraded by turbulence-induced beam distortions. This paper addresses the correction of turbulence effects on such large aperture radars by means of adaptive optics. The radar system model is of a ground-based monostatic radar doing angle-angle imaging of a

Naomi E. Zirkind; Jeffrey H. Shapiro

1989-01-01

349

The FlySafe project: How weather radars can improve the en-route bird strike warning system. Hans van Gasteren1,2  

E-print Network

1 The FlySafe project: How weather radars can improve the en-route bird strike warning system. Hans Graaf3 and Willem Bouten1 In civil aviation the majority of bird strikes occur below 1000 ft, thus civil bird strikes predominantly occur on and around aerodromes. In military aviation, however, the problem

Graaf, Martin de

350

Reference oscillator stability effect on clutter cancellation in a radar system  

NASA Astrophysics Data System (ADS)

A model to calculate the improvement value in a video processor consisting of a generic filter with only zeros for radar applications was applied to two oscillators with known characteristics. The maximum value of improvement attainable does not depend on the frequency response of the processor, nor on the behavior of the nonuniform part of the oscillator's spectrum. It is limited by the uniform level of the spectrum. Improvement values obtained from a clutter with nonideal characteristics depend on the processor. The improvement calculation was carried out starting from the spectrum (in the frequency domain). It can also be carried out in the time variable domain, by using directly the autocorrelation function. The choice made takes into account the fact that the characteristics of the oscillators are often defined in terms of the spectrum, rather than autocorrelation function.

Sabatini, S.

351

ASEISMIC SLIP EVENTS ALONG THE SOUTHERN SAN ANDREAS FAULT SYSTEM CAPTURED BY RADAR INTERFEROMETRY  

E-print Network

Aseismic slip is observed along several faults in the Salton Sea and southernmost Landers rupture zone regions using interferometric synthetic aperture radar (InSAR) data spanning different time periods between 1992 and 1997. In the southernmost Landers rupture zone, projecting south from the Pinto Mountain Fault, sharp discontinuities in the interferometric phase are observed along the sub-parallel Burnt Mountain and Eureka Peak Faults beginning three months after the Landers earthquake and is interpreted to be post-Landers after-slip. Abrupt phase offsets are also seen along the two southernmost contiguous 11 km Durmid Hill and North Shore segments of the San Andreas Fault with an abrupt termination of slip near the northern end of the North Shore Segment. A sharp phase offset is

Paul Vincent

352

Advanced ground penetrating radar  

SciTech Connect

An advanced Ground Penetrating Radar (GPR) system has the potential for efficiently and reliably providing high resolution images for inspecting concrete civil structures for defects and damage assessment. To achieve the required performance, improvements in radar hardware, and development and adaptation of advanced 2- and 3-dimensional synthetic aperture imaging techniques are needed. Recent and continuing advancement in computer and computer-related technology areas have made it possible to consider more complex and capable systems for a variety of imaging applications not previously conceived. The authors developed conceptual designs, analyzed system requirements, and performed experiments, modeling, and image reconstructions to study the feasibility of improving GPR technology for non-destructive evaluation of bridge decks and other high-value concrete structures. An overview and summary of practical system concepts and requirements, are presented.

Warhus, J.P.; Mast, J.E.; Johansson, E.M.; Nelson, S.D. [Lawrence Livermore National Lab., CA (United States). Electronics Engineering Dept.

1994-07-26

353

An Integrated Navigation System using GPS Carrier Phase for Real-Time Airborne Synthetic Aperture Radar (SAR)  

SciTech Connect

A Synthetic Aperture Radar (SAR) requires accu- rate measurement of the motion of the imaging plat- form to produce well-focused images with minimal absolute position error. The motion measurement (MoMeas) system consists of a inertial measurement unit (IMU) and a P-code GPS receiver that outputs corrected ephemeris, L1 & L2 pseudoranges, and L1 & L2 carrier phase measurements. The unknown initial carrier phase biases to the GPS satellites are modeled as states in an extended Kalman filter and the resulting integrated navigation solution has po- sition errors that change slowly with time. Position error drifts less than 1- cm/sec have been measured from the SAR imagery for various length apertures.

Fellerhoff, J. Rick; Kim, Theodore J.; Kohler, Stewart M.

1999-06-24

354

Simulation of snow stratigraphy using full-waveform inversion applied to data from an upward-looking radar system  

NASA Astrophysics Data System (ADS)

Snow stratigraphy is a key contributing factor for assessing avalanche danger, but so far only destructive methods can provide this kind of information. Furthermore, continuous monitoring of the temporal evolution of the snowpack is not possible with destructive methods. Radar technology provides information on the snowpack non-destructively and allows deriving internal snow properties from its signal response. In our previous work, we demonstrated that it is feasible to quantitatively derive snowpack properties relevant for avalanche formation and monitor their evolution in time using an upward-looking ground penetrating radar system (upGPR) that was buried in a wooden box underneath the snow. Reliable results could only be obtained for the time when the snow cover was dry. In addition, to determine some properties, we still needed additional information such as independently measured snow height or modeled snow density. Hence, the system was not yet able to provide information from avalanche starting zones, since this type of information is generally not available in avalanche-prone terrain. To fully exploit the information content of upGPR data, and thus to at least partially compensate for the lack of information, we applied full-waveform inversion (FWI) techniques. We refined the model of the snowpack by repeated forward modeling the waveforms and updating the model parameters to match it with recorded data. The forward model took into account both the effect of the snow density on the velocity of the electromagnetic wave, as well as the influence of snow wetness on the attenuation. This allowed the density and the liquid water content for each layer in the snowpack to be determined. As we conducted a measurement every 3 hours (every 30 minutes as soon as the snowpack became wet), we could also simulate the temporal evolution of the density and the liquid water profiles. The method worked without assumptions or external measurements, even when the snow cover was wet.

Schmid, Lino; Maurer, Hansruedi; Schweizer, Jürg; Heilig, Achim; Mitterer, Christoph; Okorn, Robert; Eisen, Olaf

2014-05-01

355

Application of polarimetric synthetic aperture radar interferometry for land cover classification  

Microsoft Academic Search

The development of radar polarimetry and radar interferometry is advancing rapidly. The textural fine structure, target orientation, system metrics and material constituents can be recovered with radar polarimetry; while with radar interferometry, the elevation structure of a target can be explored. Polarimetric synthetic aperture radar interferometric (Pol-InSAR) is interferometry between all possible polarization channels at each end of the baseline.

Yang Zhen; Yang Ruliang

2002-01-01

356

Dual-Frequency Radar Observations of Precipitation  

Microsoft Academic Search

An equal volume, dual-frequency radar system is used to obtain a quantitative characterization of a precipitation volume. The power back-scattered is related to the rainfall rate through the use of an assumed exponential drop-size distribution and the Mie radar cross section. A method is given whereby the relative consistency of a dual-frequency radar system is aided by calibration in the

B. Walker; L. S. Lamberth; J. J. Stephens

1964-01-01

357

Agricultural and hydrological applications of radar  

NASA Technical Reports Server (NTRS)

Program objectives, covering a wide range of disciplines and activities in radar remote sensing, include radar systems development and analysis, data processing and display, and data interpretation in geology, geography and oceanography. Research was focused on the evaluation of radar remote sensing applications in hydrology and agriculture based on data acquired with the Microwave Active Spectrometer (MAS) system. The title, author(s) and abstract of each of the 62 technical reports generated under this contract are appended.

Ulaby, F. T.

1976-01-01

358

Weather Radar Fundamentals  

NSDL National Science Digital Library

This 2-hour module presents the fundamental principles of Doppler weather radar operation and how to interpret common weather phenomena using radar imagery. This is accomplished via conceptual animations and many interactive radar examples in which the user can practice interpreting both radar reflectivity and radar velocity imagery. Although intended as an accelerated introduction to understanding and using basic Doppler weather radar products, the module can also serve as an excellent refresher for more experienced users.

Comet

2012-03-21

359

TerraSAR-X high-resolution radar remote sensing: an operational warning system for Rift Valley fever risk.  

PubMed

In the vicinity of the Barkedji village (in the Ferlo region of Senegal), the abundance and aggressiveness of the vector mosquitoes for Rift Valley fever (RVF) are strongly linked to rainfall events and associated ponds dynamics. Initially, these results were obtained from spectral analysis of high-resolution (~10 m) Spot-5 images, but, as a part of the French AdaptFVR project, identification of the free water dynamics within ponds was made with the new high-resolution (down to 3-meter pixels), Synthetic Aperture Radar satellite (TerraSAR-X) produced by Infoterra GmbH, Friedrichshafen/Potsdam, Germany. During summer 2008, within a 30 x 50 km radar image, it was found that identified free water fell well within the footprints of ponds localized by optical data (i.e. Spot-5 images), which increased the confidence in this new and complementary remote sensing technique. Moreover, by using near real-time rainfall data from the Tropical Rainfall Measuring Mission (TRMM), NASA/JAXA joint mission, the filling-up and flushing-out rates of the ponds can be accurately determined. The latter allows for a precise, spatio-temporal mapping of the zones potentially occupied by mosquitoes capable of revealing the variability of pond surfaces. The risk for RVF infection of gathered bovines and small ruminants (~1 park/km(2)) can thus be assessed. This new operational approach (which is independent of weather conditions) is an important development in the mapping of risk components (i.e. hazards plus vulnerability) related to RVF transmission during the summer monsoon, thus contributing to a RVF early warning system. PMID:21080318

Vignolles, Cécile; Tourre, Yves M; Mora, Oscar; Imanache, Laurent; Lafaye, Murielle

2010-11-01

360

Applications of Ground Penetrating Radar in Bridge Health Monitoring Using Different Frequency Antennae Systems  

NASA Astrophysics Data System (ADS)

Inspection and assessment of bridge structures within the context of health monitoring of structures as well as the life cycle of structures is of paramount importance for structural engineers and bridge owners. No doubt the early detection of structural defects in particular internal structural elements such as bridge deck delamination, formation of cracks and corrosion of rebar will enable engineers to remedy the imperfection and prolong the serviceability of the structure. Applications of Ground Penetrating Radar (GPR) have proved to be effective in detecting such imperfections if utilised correctly. This paper presents and discusses the applications of GPR in assessing the structural integrity of a heavily used bridge in a town centre position (Pentagon Road Bridge, Chatham, Kent, UK) using different antennae in terms of frequency and method of application (2 GHz and 200-600 MHz GPR antennae). The paper focuses on the effectiveness of using the 'correct' tool and data processing in terms of better understanding possible structural defects. Processing, interpretation and analysis of collected data were supported by GRED software, with three-dimensional scanning capabilities. Reported results illustrate the effectiveness of GPR mapping providing valuable information regarding the positions of rebar (upper and lower reinforcement), unknown structural features as well as possible moisture ingress within the structure. The results also demonstrate a possible phenomenon in identifying the presence of moisture within the bridge deck confirming a similar finding in an earlier case (Forth Road Bridge in Scotland). Keywords: Bridge; Structure; Health Monitoring; Moisture Ingress.

Alani, A.; Kilic, G.; Aboutalebi, M.

2012-04-01

361

New law enforcement applications of millimeter-wave radar  

NASA Astrophysics Data System (ADS)

Recent advances in millimeter-wave (MMW) radar technologies provide new applications for law enforcement use over-and- above the venerable speed timing radar. These applications include the potential to detect weapons under clothing and to conduct surveillance through walls. Concealed Weapon Detection and covert surveillance are of high interest to both the Department of Defense in support of Small Unit Operations and the Justice Department for civilian law enforcement applications. MMW sensors are under development which should provide the needed capabilities including radiometric sensors at 95 GHz, active 95 GHz real aperture radars, active focal plane array (FPA) radars, and holographic radars. Radiometric sensors include 2D FPA systems, 1D FPA, scanned systems, and single element scanned sensors. Active FPA radars include illuminated radiometric systems and coherent radar systems. Real aperture MMW radar systems include raster scanned and conical scanned sensors. Holographic systems ruse mechanical scanners to collect coherent data over a significant solid angular sector.

Currie, Nicholas C.; Ferris, David D., Jr.; McMillan, Robert W.; Wicks, Michael C.

1997-06-01

362

Electro optical radar transmission chain modeling and simulation  

Microsoft Academic Search

In traditional radar systems, the use of electronic analog devices, such as mixers and oscillators, introduces some noise sources which complicate the realization of a completely digital radar systems. In fact, non linear behaviors of such systems as well as low Spurious Free Dynamic Range (SFDR) and low phase coherence, compromise radar performance in terms of detection and coherent signal

Francesco Laghezza; Amerigo Capria; Andrea Cacciamano; Fabrizio Berizzi; Paolo Ghelfi; Antonella Bogoni

2011-01-01

363

New weather radar coming  

NASA Astrophysics Data System (ADS)

What would you call the next generation of radar for severe weather prediction? NEXRAD, of course. A prototype for the new system was recently completed in Norman, Okla., and by the early 1990s up to 195 stations around the United States will be tracking dangerous weather and sending faster, more accurate, and more detailed warnings to the public.NEXRAD is being built for the Departments of Commerce, Transportation, and Defense by the Unisys Corporation under a $450 million contract signed in December 1987. Th e system will be used by the National Weather Service, the Federal Aviation Administration (FAA), and the U.S. Air Force and Navy. The NEXRAD radar tower in Norman is expected to be operational in October.

Maggs, William Ward

364

Structure of precipitating systems over Taiwan’s complex terrain during Typhoon Morakot (2009) as revealed by weather radar and rain gauge observations  

NASA Astrophysics Data System (ADS)

This study documents from an observational perspective the structure of precipitation systems over the complex topography of Taiwan as Typhoon Morakot (2009) impinged on the island on 8 August 2009. An advanced multiple-Doppler radar synthesis technique particularly designed for dealing with non-flat surfaces is applied to analyze the three-dimensional wind fields over the ocean and terrain. In the northern and southern portion of the analysis domain where the mountain slope is relatively gentle and steep, respectively, the radar reflectivity measurements indicate that the precipitation systems exhibit very distinct features, namely, horizontal translation in the north and abrupt intensification in the south. While still far from the southern mountainous region, a north-south oscillation of an east-west-oriented band of strong radar reflectivity (>40 dBZ) with a horizontal span of 20 km is observed. Along the mountain slopes, the band of strong radar reflectivity has a much wider north-south extent. Both the radar and rain gauge observations show that the major precipitation is primarily confined to the windward side of the mountains. An analysis of the saturated Brunt-Väisälä frequency reveals that the upstream atmosphere is statically unstable, which implies that the lifting of the incoming convective cells by the topography will easily trigger precipitation. Thus, most of the moisture will be consumed before the air reaches the leeward side of the mountains. The long duration and the wide range of heavy precipitation in the mountainous regions resulted in a record-breaking average (over the gauges) rainfall amount of 2000 mm over 4 days. The prevailing winds approaching the mountains are from the west. The cross-barrier wind speed has a maximum (?40 m s-1) above the mountain crest that can be reasonably explained by a simplified shallow water model. The capability of applying the weather radar to provide a reliable quantitative estimate of the rainfall over a large area with high temporal and spatial resolution is demonstrated using dual-polarimetric radar data. The potential applications of the knowledge of the wind and precipitation characteristics in hydrology and other fields are addressed in this manuscript.

Liou, Yu-Chieng; Wang, Tai-Chi Chen; Tsai, Yi-Chun; Tang, Yu-Shuang; Lin, Pay-Liam; Lee, Yung-An

2013-12-01

365

The impact of reflectivity correction and conversion methods to improve precipitation estimation by weather radar for an extreme low-land Mesoscale Convective System  

NASA Astrophysics Data System (ADS)

Between 25 and 27 August 2010 a long-duration mesoscale convective system was observed above the Netherlands. For most of the country this led to over 15 hours of near-continuous precipitation, which resulted in total event accumulations exceeding 150 mm in the eastern part of the Netherlands. Such accumulations belong to the largest sums ever recorded in this country and gave rise to local flooding. Measuring precipitation by weather radar within such mesoscale convective systems is known to be a challenge, since measurements are affected by multiple sources of error. For the current event the operational weather radar rainfall product only estimated about 30% of the actual amount of precipitation as measured by rain gauges. In the current presentation we will try to identify what gave rise to such large underestimations. In general weather radar measurement errors can be subdivided into two different groups: 1) errors affecting the volumetric reflectivity measurements taken, and 2) errors related to the conversion of reflectivity values in rainfall intensity and attenuation estimates. To correct for the first group of errors, the quality of the weather radar reflectivity data was improved by successively correcting for 1) clutter and anomalous propagation, 2) radar calibration, 3) wet radome attenuation, 4) signal attenuation and 5) the vertical profile of reflectivity. Such consistent corrections are generally not performed by operational meteorological services. Results show a large improvement in the quality of the precipitation data, however still only ~65% of the actual observed accumulations was estimated. To further improve the quality of the precipitation estimates, the second group of errors are corrected for by making use of disdrometer measurements taken in close vicinity of the radar. Based on these data the parameters of a normalized drop size distribution are estimated for the total event as well as for each precipitation type separately (convective, stratiform and undefined). These are then used to obtain coherent parameter sets for the radar reflectivity-rainfall rate (Z-R) and radar reflectivity-attenuation (Z-k) relationship, specifically applicable for this event. By applying a single parameter set to correct for both sources of errors, the quality of the rainfall product improves further, leading to >80% of the observed accumulations. However, by differentiating between precipitation type no better results are obtained as when using the operational relationships. This leads to the question: how representative are local disdrometer observations to correct large scale weather radar measurements? In order to tackle this question a Monte Carlo approach was used to generate >10000 sets of the normalized dropsize distribution parameters and to assess their impact on the estimated precipitation amounts. Results show that a large number of parameter sets result in improved precipitation estimated by the weather radar closely resembling observations. However, these optimal sets vary considerably as compared to those obtained from the local disdrometer measurements.

Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko

2014-05-01

366

Joint deinterleaving\\/recognition of radar pulses  

Microsoft Academic Search

An electronic support measures (ESM) system consists of a passive radar receiver that receives and measures the monopulse parameters of pulses emitted by radars in its instantaneous view, and a deinterleaver that sorts these pulses and groups them into individual cells. The cell parameters are compared with those stored in the threat library of the electronic warfare (EW) system to

Hossam E. Abou-Bakr Hassan; Franqois Chan; Y. T. Chan

2003-01-01

367

Wind shear radar simulation  

NASA Technical Reports Server (NTRS)

Viewgraphs used in a presentation on wind shear radar simulation are given. Information on a microburst model of radar reflectivity and wind velocity, radar pulse output, the calculation of radar return, microburst power spectrum, and simulation plans are given. A question and answer session is transcribed.

Britt, Charles L.

1988-01-01

368

A probabilistic approach of the Flash Flood Early Warning System (FF-EWS) in Catalonia based on radar ensemble generation  

NASA Astrophysics Data System (ADS)

Early Warning Systems (EWS) are commonly identified as the most efficient tools in order to improve the preparedness and risk management against heavy rains and Flash Floods (FF) with the objective of reducing economical losses and human casualties. In particular, flash floods affecting torrential Mediterranean catchments are a key element to be incorporated within operational EWSs. The characteristic high spatial and temporal variability of the storms requires high-resolution data and methods to monitor/forecast the evolution of rainfall and its hydrological impact in small and medium torrential basins. A first version of an operational FF-EWS has been implemented in Catalonia (NE Spain) under the name of EHIMI system (Integrated Tool for Hydrometeorological Forecasting) with the support of the Catalan Water Agency (ACA) and the Meteorological Service of Catalonia (SMC). Flash flood warnings are issued based on radar-rainfall estimates. Rainfall estimation is performed on radar observations with high spatial and temporal resolution (1km2 and 10 minutes) in order to adapt the warning scale to the 1-km grid of the EWS. The method is based on comparing observed accumulated rainfall against rainfall thresholds provided by the regional Intensity-Duration-Frequency (IDF) curves. The so-called "aggregated rainfall warning" at every river cell is obtained as the spatially averaged rainfall over its associated upstream draining area. Regarding the time aggregation of rainfall, the critical duration is thought to be an accumulation period similar to the concentration time of each cachtment. The warning is issued once the forecasted rainfall accumulation exceeds the rainfall thresholds mentioned above, which are associated to certain probability of occurrence. Finally, the hazard warning is provided and shown to the decision-maker in terms of exceeded return periods at every river cell covering the whole area of Catalonia. The objective of the present work includes the probabilistic component to the FF-EWS. As a first step, we have incorporated the uncertainty in rainfall estimates and forecasts based on an ensemble of equiprobable rainfall scenarios. The presented study has focused on a number of rainfall events and the performance of the FF-EWS evaluated in terms of its ability to produce probabilistic hazard warnings for decision-making support.

Velasco, David; Sempere-Torres, Daniel; Corral, Carles; Llort, Xavier; Velasco, Enrique

2010-05-01

369

Radar emitter signal recognition based on support vector machines  

Microsoft Academic Search

Radar emitter signal recognition plays an important role in electronic intelligence systems and electronic support measure systems. To heighten accurate recognition rate of radar emitter signals, this paper proposes a hierarchical classifier structure to recognize radar emitter signals. The proposed structure combines resemblance coefficient classifier, support vector machines with binary tree architecture and linear classifier based on Mahalanobis distance. Experimental

Gexiang Zhang; Weidong Jin; Laizhao Hu

2004-01-01

370

The magmatic system beneath Torfajökull volcano, Iceland: A combination of radar and seismic interferometric analysis  

NASA Astrophysics Data System (ADS)

Torfajökull is the largest silicic volcanic centre in Iceland; it erupts infrequently, with only two eruptions in the last 1200 years, the latest of which was over 5 centuries ago. However, ongoing seismicity, deformation and geothermal activity within its large caldera (18x12 km diameter) indicate the continued presence of a long-lasting magma chamber. Using radar interferometry (InSAR) time series we analyse the area covering Torfajökull volcano. In addition to displacements related to the tectonic spreading of the area, we detect a pattern of subsidence in the SW region of Torfajökull's caldera, on-going since at least 1993, at rates of up to ~13 mm yr-1. The data can be fit reasonably well using a model of a NE-SW oriented spheroidal body at ~5 km depth, undergoing a pressure decrease that is uniform in space and time. One potential interpretation for this deformation is therefore that it is due to the presence of a cooling magma chamber. The estimated surface displacements from InSAR can be used to constrain the pressure change. However, because the resolution of the inferred magma chamber is poor and the elastic/rheological properties are not known, we do not have a unique solution. More insight into the geometry and rock properties can be gained using seismic interferometry (SI); cross-correlation of natural signals can be used to generate seismic records that simulate active sources, allowing tomographic analysis. For the SI processing we use seismic data acquired during 2005 at 30 stations sparsely distributed around the Torfajökull area. We divide the ambient noise recorded at two stations in portions of 1h, cross-correlate the corresponding portions and then sum the correlated results. The result is a retrieved surface-wave part of the Green's function between the two stations. This is repeated between all pairs of stations. Careful assessment of the quality of the retrieved Green's functions for small time windows allows analysis of the microseism noise. The results show that the microseisms are dominant in the NW-SE direction and the resulting retrieved surface waves propagate at ~3 km/s in the double-frequency microseism band. Dispersion curves are derived based on the cross-correlation results. The retrieved dispersion curves between pairs of stations are then used in tomographic inversion for the derivation of the 3D S-wave velocity distribution in the subsurface. We then use this subsurface wave velocity field, including uncertainties, as a prior constraint on the geometry of the deflating pressure source in our inversion using InSAR observations.

Martins, J.; Hooper, A. J.; Draganov, D.; Ruigrok, E.; Hanssen, R. F.; White, R. S.; Soosalu, H.

2013-12-01

371

Aseismic Slip Events along the Southern San Andreas Fault System Captured by Radar Interferometry  

SciTech Connect

A seismic slip is observed along several faults in the Salton Sea and southernmost Landers rupture zone regions using interferometric synthetic aperture radar (InSAR) data spanning different time periods between 1992 and 1997. In the southernmost Landers rupture zone, projecting south from the Pinto Mountain Fault, sharp discontinuities in the interferometric phase are observed along the sub-parallel Burnt Mountain and Eureka Peak Faults beginning three months after the Landers earthquake and is interpreted to be post-Landers after-slip. Abrupt phase offsets are also seen along the two southernmost contiguous 11 km Durmid Hill and North Shore segments of the San Andreas Fault with an abrupt termination of slip near the northern end of the North Shore Segment. A sharp phase offset is seen across 20 km of the 30 km-long Superstition Hills Fault before phase decorrelation in the Imperial Valley along the southern 10 km of the fault prevents coherent imaging by InSAR. A time series of deformation interferograms suggest most of this slip occurred between 1993 and 1995 and none of it occurred between 1992 and 1993. A phase offset is also seen along a 5 km central segment of the Coyote Creek fault that forms a wedge with an adjoining northeast-southwest trending conjugate fault. Most of the slip observed on the southern San Andreas and Superstition Hills Faults occurred between 1993 and 1995--no slip is observed in the 92-93 interferograms. These slip events, especially the Burnt Mountain and Eureka Peak events, are inferred to be related to stress redistribution from the June, 1992 M{sub w} = 7.3 Landers earthquake. Best-fit elastic models of the San Andreas and Superstition Hills slip events suggest source mechanisms with seismic moments over three orders of magnitude larger than a maximum possible summation of seismic moments from all seismicity along each fault segment during the entire 4.8-year time interval spanned by the InSAR data. Aseismic moment releases of this magnitude (equivalent to M{sub w} = 5.3 and 5.6 events on the Superstition Hills and San Andreas Faults respectively) are hitherto unknown and have not been captured previously by any geodetic technique.

Vincent, P

2001-10-01

372

Analysis of synthetic aperture radar imagery  

NASA Technical Reports Server (NTRS)

Some problems faced in applications of radar measurements in hydrology are: (1) adequate calibration of the radar systems and direct digital data will be required in order that repeatable data can be acquired for hydrologic applications; (2) quantitative hydrologic research on a large scale will be prohibitive with aircraft mounted synthetic aperture radar systems due to the system geometry; (3) spacecraft platforms appear to be the best platforms for radar systems when conducting research over watersheds larger than a few square kilometers; (4) experimental radar systems should be designed to avoid use of radomes; and (5) cross polarized X and L band data seem to discriminate between good and poor hydrologic cover better than like polarized data.

Blanchard, B. J.

1977-01-01

373

Optical Metrology System for Radar Phase Correction on Large Flexible Structure  

Microsoft Academic Search

In aerospace applications there is an increasing interest in metrology systems. Metrology systems are used in applications such as wave front correction and formation flying, for measuring deployable structure deformation\\/oscillations, and as the crude stage for interferometer missions. In this paper we describe a concept for a metrology system. The metrology system concept will be able to determine the Cartesian

C. C. Liebe; A. Abramovici; R. K. Bartman; J. Chapsky; L. Chapsky; K. Coste; R. Lam

2008-01-01

374

Development of coherent laser radar  

Microsoft Academic Search

Over the past 25 years many coherent laser radar systems have been developed and applied to a variety of problems, including military systems to image solid objects and map their velocities. This paper addresses primarily civilian applications of coherent lidar systems for observations of the atmosphere.

Madison J. Post

1994-01-01

375

Pointing mechanisms for the Shuttle Radar Laboratory  

NASA Technical Reports Server (NTRS)

The Shuttle Radar Laboratory (SRL) is scheduled for launch in December of 1993 on the first of its two missions. The SRL has three major radar instruments: two distributed phased-array antennas, which make up the Spaceborne Imaging Radar-C System (SIR-C) and are capable of being electronically steered, and one X-Band Synthetic Aperture Radar (X-SAR), which is pointed mechanically by a suite of mechanisms. This paper will describe these mechanisms and summarize the development difficulties that were encountered in bringing them from the design stage through prototype development and protoflight testing.

Lilienthal, Gerald W.; Olivera, Argelio M.; Shiraishi, Lori R.

1993-01-01

376

PRISM: An In-Vehicle CPU-Oriented Novel Azimuth Estimation Technique for Electronic-Scan 76GHz Adaptive-Cruise-Control Radar System  

Microsoft Academic Search

In this paper, we have developed a novel azimuth- estimation technique for 76-GHz adaptive-cruise-control radar systems. To resolve the rank deficiency of the signal covariance matrix and to decrease the influence of dominant noise components, we used an improved SS technique. To balance computational cost with azimuth resolution for in-vehicle implementation, we introduced a projection matrix kernel, which formally is

Kazuo Shirakawa

2008-01-01

377

Applications of the HI-CLASS (high-performance CO2 laser radar surveillance sensor) laser system for active imaging of space objects  

Microsoft Academic Search

The HI-CLASS is a high power, wideband, coherent laser radar (ladar) for long range detection, tracking, and imaging located at the Maui Space Surveillance Site. HI-CLASS will be used to provide high precision metrics as well as information for images of space objects and remote sensing with the same system. The four phases of the HI-CLASS hardware development program were

Debora E. Mosley; Charles L. Matson

1998-01-01

378

A satellite-based radar wind sensor  

NASA Technical Reports Server (NTRS)

The objective is to investigate the application of Doppler radar systems for global wind measurement. A model of the satellite-based radar wind sounder (RAWS) is discussed, and many critical problems in the designing process, such as the antenna scan pattern, tracking the Doppler shift caused by satellite motion, and backscattering of radar signals from different types of clouds, are discussed along with their computer simulations. In addition, algorithms for measuring mean frequency of radar echoes, such as the Fast Fourier Transform (FFT) estimator, the covariance estimator, and the estimators based on autoregressive models, are discussed. Monte Carlo computer simulations were used to compare the performance of these algorithms. Anti-alias methods are discussed for the FFT and the autoregressive methods. Several algorithms for reducing radar ambiguity were studied, such as random phase coding methods and staggered pulse repitition frequncy (PRF) methods. Computer simulations showed that these methods are not applicable to the RAWS because of the broad spectral widths of the radar echoes from clouds. A waveform modulation method using the concept of spread spectrum and correlation detection was developed to solve the radar ambiguity. Radar ambiguity functions were used to analyze the effective signal-to-noise ratios for the waveform modulation method. The results showed that, with suitable bandwidth product and modulation of the waveform, this method can achieve the desired maximum range and maximum frequency of the radar system.

Xin, Weizhuang

1991-01-01

379

Use of radar for nonintrusive subsurface investigations  

SciTech Connect

Finding and mapping buried hazardous waste can be a time-consuming process. However, advances in ground-penetrating radar technology are improving the means by which to detect subsurface features and related contamination. Geophysical Survey Systems, Inc. (North Salem, New Hampshire) has developed an innovative ground-penetrating radar system. The Subsurface Interface Radar (SIR{reg_sign}) system can provide real-time and continuous-profile records that indicate the location and depth of objects within subsurfaces of soil, concrete, rock, water, or other dielectric materials. The SIR{reg_sign} system allows the user to investigate subsurface conditions in a nonintrusive manner; this radar can locate underground storage tanks and buried drums, delineate landfill boundaries and burial trenches, and in some cases, the radar can identify hydrocarbon plums.

NONE

1995-07-01

380

Spaceborne Imaging Radar Project  

NASA Technical Reports Server (NTRS)

In June of 1985 the Project Initiation Agreement was signed by the Jet Propulsion Laboratory and the NASA Office of Space Science and Applications for the Spaceborne Imaging Radar Project (SIR). The thrust of the Spaceborne Imaging Radar Project is to continue the evolution of synthetic aperture radar (SAR) science and technology developed during SEASAT, SIR-A and SIR-B missions to meet the needs of the Earth Observing System (EOS) in the mid 1990's. As originally formulated, the Project plans were for a reflight of the SIR-B in 1987, the development of a new SAR, SIR-C, for missions in mid 1989 and early 1990, and the upgrade of SIR-C to EOS configuration with a qualification flight aboard the shuttle in the 1993 time frame (SIR-D). However, the loss of the shuttle Challenger has delayed the first manifest for SIR to early 1990. This delay prompted the decision to drop SIR-B reflight plans and move ahead with SIR-C to more effectively utilize this first mission opportunity. The planning for this project is discussed.

Herman, Neil

1986-01-01

381

Modern FMCW radar - techniques and applications  

Microsoft Academic Search

The range of practical applications for FMCW radars has increased significantly in the last decade or so. This paper renews some of the recent applications and also some of the techniques which are now being applied to improve the versatility and performance of FMCW radars. Significant system developments include the use of moving-target detection techniques, the development of the automotive

A. G. Stove

2004-01-01

382

Imaging radar for bridge deck inspection  

Microsoft Academic Search

Lawrence Livermore National Laboratory is developing a prototype imaging radar for inspecting steel reinforced concrete bridge decks. The system is designed to acquire synthetic aperture radar data and provide high-resolution images of internal structure, flaws, and defects enabling bridge inspectors to nondestructively evaluate and characterized bridge deck condition. Concrete delamination resulting from corrosion of steel reinforcing bars (rebars) is an

John P. Warhus; Jeffrey E. Mast; Scott D. Nelson

1995-01-01

383

Radar Signals Sorting with Kohonen Neural Net  

Microsoft Academic Search

Kohonen neural network is capable of self-organizing and recognizing clustering center, which is used in many artificial Intelligence (AI) fields. A radar electronic support measures (ESM) system must sort the received radar pulse signal to cells with the same features according to the single pulse parameters, such as radio frequency (RF), angle of arrival (AOA), pulse width (PW), etc. Considering

Chuang Zhao; Yongjun Zhao; Jianqi Lu

2006-01-01

384

Roadrunner: A novel radar guidance concept  

Microsoft Academic Search

An exploratory development program aimed at demonstrating a novel radar navigation\\/guidance scheme which enables a small unmanned aircraft (drone) to follow roads is presented. Since vehicles on the road can be easily detected, this aircraft could be used as either a strike vehicle itself or as a reconnaissance adjunct to another strike system. The guidance scheme involves onboard radar measurements

J. R. Kelsey

1979-01-01

385

GSFC short pulse radar, JONSWAP-75  

NASA Technical Reports Server (NTRS)

In September 1975, the Goddard Space Flight Center operated a short pulse radar during ocean wave measuring experiments off the coast of West Germany in the North Sea. The experiment was part of JONSWAP-75. The radar system and operations during the experiment are described along with examples of data.

Levine, D. M.; Walton, W. T.; Eckerman, J.; Kutz, R. L.; Dombrowski, M.; Kalshoven, J. E., Jr.

1977-01-01

386

Ship signatures in synthetic aperture radar imagery  

Microsoft Academic Search

Ship signatures in synthetic aperture radar (SAR) imagery have been matched to Automatic Identification System (AIS) data to yield a large database of known ships for ship signature analysis. This paper focuses on ship radar cross section and ship length derived from the ship signature length. Cross- polarization is an attractive option for ship detection.

Paris W. Vachon; Ryan A. English; John Wolfe

2007-01-01

387

Radar signature control of wind turbine generators  

Microsoft Academic Search

Many of the prime locations for wind farms in the UK are on exposed landscapes close to regional airports. However, planning permission for such installations is often being denied because the moving blades of the wind turbines interfere with the operation of airport radar systems. Airport surveillance radars track the position and speed of aircraft in their surrounding airspace using

A. Tennant; B. Chambers

2005-01-01

388

A space-based microwave radar concept  

NASA Technical Reports Server (NTRS)

A space-based microwave radar (SBR) concept is defined using a tether trans-receive antenna supported between two gravity gradient low earth-orbiting satellites. A cluster of four tether antennas each of 6 km maximum length and 1.5 km separation between tethers constitutes a radar. A system of eight to eleven such clusters constitutes the overall radar scheme which will cover approximately one third of the earth surface for detecting sea-based targets. Issues identified are the array structure, coherence of tethered arrays, grating lobe energy clamping, clutter effects, communications, system requirements and the overall radar system concept including stability considerations. This paper presents the base-line definition of an alternate space-based radar scheme.

Chakraborty, D.

1992-01-01

389

European near-Earth object radar  

NASA Astrophysics Data System (ADS)

Radar astronomy paradox (RAP): practically everybody agree with essential contributions of active radar observations to Solar System and especially to near-Earth object (NEO) explorations, but despite everything prefer to develop new and new passive telescopes and disposable space missions, only, and nobody want to build at least one dedicated multipurpose radar telescope (neither Arecibo nor Goldstone and Evpatoria radars were created as dedicated radar astronomy instruments). Also, as of June 2002, among of 188 radar detected asteroids and comets there are only 3 NEOs, which were investigated in Europe, with single European radar facility, sited in Evpatoria. The main reason of such deep gap is a low sensitivity of Evpatoria radar, which is in 10 and 300 times less powerful than Goldstone and Arecibo. Therefore, I guess the first dedicated European NEO Radar (ENEOR) is earnestly needful now. From time to time we discuss this problem, but it is not solve for the present moment, perhaps because of above formulated RAP. Origin and concept of the ENEOR, as well as the ENEOR project, based on the being under construction 64-m Sardinia Radio Telescope, will be presented below.

Zaitsev, Alexander L.

2002-11-01

390

Proprocessing: Geocoding of AVIRIS Data Using Navigation, Engineering, DEM, and Radar Tracking System Data  

NASA Technical Reports Server (NTRS)

Remotely sensed data have geometric characteristics and representation which depend on the type of the acquisition system used. To correlate such data over large regions with other real world representation lools like conventional maps or Geographic Information Systems (GIS) for verification purposes, or for further treatment within different data sets, a coregistration has to be performed.

Meyer, P.; Larson, S. A.; Hansen, E. G.; Itten, K. I

1993-01-01

391

Radar Cuts Subsoil Survey Costs  

NASA Technical Reports Server (NTRS)

Soil features located with minimum time and labor. Ground-penetrating radar (GPR) system supplements manual and mechanical methods in performing subsurface soil survey. Mobile system obtains graphic profile of soil discontinuities and interfaces as function of depth. One or two test borings necessary to substantiate soil profile. GPR proves useful as reconnaissance tool.

Johnson, R.; Glaccum, R.

1984-01-01

392

Karhunen - Loeve Transformation in Radar Signal Features Processing  

Microsoft Academic Search

One of the most difficult tasks in the radar signal processing is an optimal features extraction and classification. The multifunction radar systems can not be classified and precisely recognized by most of new and modern Electronic Support Measure and Electronic Intelligence devices in the real time. It is directly combined with a possibility of measurement radar features. The number of

A. Kawalec; R. Owczarek; J. Dudczyk

2006-01-01

393

EMP (electro-magnetic pulse) hardening of a relocatable radar  

Microsoft Academic Search

The problem of ensuring radar survivability in a HEMP (high-altitude electromagnetic pulse) environment is examined with particular reference to experimental results obtained for the relocatable TRS 22XX radar. The approach used here is global hardening, whereby the whole system except the antenna is enclosed in a Faraday cage. Every penetration of the radar station is protected, the energy input is

G. J. Deville

1987-01-01

394

A Kernel Density Window Clustering Algorithm for Radar Pulses  

Microsoft Academic Search

As radar signal environments become denser and more complex, the capability of high-speed and accurate signal analysis is required for ES (electronic warfare support) system to identify individual radar signals at real-time. In this paper, we propose the novel clustering algorithm of radar pulses to alleviate the load of signal analysis process and support reliable analysis. The proposed algorithm uses

Dong-Weon Lee; Jin-Woo Han; Kyu-Ha Song; Won Don Lee

2008-01-01

395

Flight Test Results for a Turbulence Detection Radar  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides an overview of flight tests conducted on an aircraft turbulence detection radar system. Topics covered include: flight operations summary, radar data collection, baseline algorithm methodology, radar hazard tables and proposed alert criteria. Flight tests results are presented and summarized. Data analysis from these flight tests are also included.

Schaffner, Phil

2003-01-01

396

New techniques applied to air-traffic control radars  

Microsoft Academic Search

During the past two years a program has been carried out to show how new techniques can greatly improve the performance of radars used for air-traffic control. A survey of problems associated with presently used radars was undertaken. This survey indicates that primary radar in an automated air-traffic control system can be made significantly more effective by the use of

CHARLES E. MUEHE; LINCOLN CARTLEDGE; WILLIAM H. DRURY; EDWARD M. HOFSTETTER; MELVIN LABITT; PETER B. McCORISON; VINCENT J. SFERRINO

1974-01-01

397

Model-based object recognition using laser radar range imagery  

Microsoft Academic Search

The combined effects of laser speckle and local oscillator shot noise degrade coherent laser radar range measurements. As a result, laser radar range imagery suffers from both uniformly-distributed range anomalies and Gaussian-distributed local range errors. Our goal in this research is to develop a target recognition system capable of recognizing military vehicles in range images provided by airborne laser radars.

Asuman E. Koksal; Jeffrey H. Shapiro; William M. Wells

1999-01-01

398

Computer simulation of a multiple-aperture coherent laser radar  

Microsoft Academic Search

This paper presents the construction of a 2D multiple aperture coherent laser radar simulation that is capable of including the effects of the time evolution of speckle on the laser radar output. Every portion of a laser radar system is modeled in software, including quarter and half wave plates, beamsplitters (polarizing and non-polarizing), the detector, the laser source, and all

Kevin J. Gamble

1996-01-01

399

Study to investigate and evaluate means of optimizing the radar function for the space shuttle. [(pulse radar)  

NASA Technical Reports Server (NTRS)

Results are discussed of a study to define a radar and antenna system which best suits the space shuttle rendezvous requirements. Topics considered include antenna characteristics and antenna size tradeoffs, fundamental sources of measurement errors inherent in the target itself, backscattering crosssection models of the target and three basic candidate radar types. Antennas up to 1.5 meters in diameter are within specified installation constraints, however, a 1 meter diameter paraboloid and a folding, four slot backfeed on a two gimbal mount implemented for a spiral acquisition scan is recommended. The candidate radar types discussed are: (1) noncoherent pulse radar (2) coherent pulse radar and (3) pulse Doppler radar with linear FM ranging. The radar type recommended is a pulse Doppler with linear FM ranging. Block diagrams of each radar system are shown.

1975-01-01

400

Bayesian radar data cube processing and syntactic tracking  

NASA Astrophysics Data System (ADS)

The output of a GMTI tracker (such as the VS-IMM) over an extended period of time can be viewed as generating a string sequence (namely the mode sequence) that defines the trajectory. In previous work, it was demonstrated with real data that the target trajectory could be (probabilistically) parsed in real-time, assuming any string sequence output from the tracker could arise only from a stochastic context-free grammar (SCFG). In this paper, an GMTI data processing chain, with a view towards the application to syntactic parsing, is presented. An emphasis is placed on the Bayesian formualtions, which provides a unified description of the processing algorithms.

Balaji, Bhashyam

2011-06-01

401

Study on ground clutter prevention fences for boundary layer radars  

NASA Astrophysics Data System (ADS)

A low elevation sidelobe suppression algorithm based on the uniform physical theory of diffraction (PTD) is developed to simulate ground clutter prevention fences for boundary layer radars (BLRs). As applications to the algorithm, the most suitable fence is achieved for the lower troposphere radar (LTR) and the L-28 boundary layer radar, respectively. The developed algorithm can also be applied to other radar systems where reducing low elevation sidelobes is desired.

Rao, Qinjiang; Hashiguchi, Hiroyuki; Fukao, Shoichiro

2003-04-01

402

Active laser radar systems with stochastic electromagnetic beams in turbulent atmosphere  

Microsoft Academic Search

Propagation of stochastic electromagnetic beams through paraxial ABCD optical systems operating through turbulent atmosphere is investigated with the help of the ABCD matrices and the generalized Huygens-Fresnel integral. In particular, the analytic formula is derived for the cross-spectral density matrix of an electromagnetic Gaussian Schell-model (EGSM) beam. We applied our analysis for the ABCD system with a single lens located

Yangjian Cai; Olga Korotkova; Halil T. Eyyuboglu; Yahya Baykal

2008-01-01

403

Space reflectors for radar and astronomy.  

PubMed

A new concept to utilize large flat optical reflecting surfaces in space to increase by several orders of magnitude the sensitivity and resolution of earth laser radar and astronomy measurements is described. The physical principles on which simple structures can maintain the optical reflectance gratings in space are derived, and the data processing requirements of the measurements are discussed. Space and ground system designs are given for a high resolution earth resources laser radar sensor, a synchronous earth and planetary science laser radar system, and an astronomy observation system including a variable very long compound grating interferometer system. PMID:20134917

Yater, J C

1975-02-01

404

Simultaneous dual-band radar development  

NASA Technical Reports Server (NTRS)

Efforts to design and construct an airborne imaging radar operating simultaneously at L band and X band with an all-inertial navigation system in order to form a dual-band radar system are described. The areas of development include duplex transmitters, receivers, and recorders, a control module, motion compensation for both bands, and adaptation of a commercial inertial navigation system. Installation of the system in the aircraft and flight tests are described. Circuit diagrams, performance figures, and some radar images are presented.

Liskow, C. L.

1974-01-01

405

USAGE OF RADARS FOR WIND ENERGY APPICATIONS Determine the benefit of using radar observations for wind energy applications by  

E-print Network

USAGE OF RADARS FOR WIND ENERGY APPICATIONS TASK: Determine the benefit of using radar observations for wind energy applications by analyzing i) the resolution effects and ii) sensitivity effects of weather radar systems. MOTIVATION: Wind energy applications strongly focus high-resolution wind observations

406

A Parallel, High-Fidelity Radar Model  

NASA Astrophysics Data System (ADS)

Accurate modeling of Space Surveillance sensors is necessary for a variety of applications. Accurate models can be used to perform trade studies on sensor designs, locations, and scheduling. In addition, they can be used to predict system-level performance of the Space Surveillance Network to a collision or satellite break-up event. A high fidelity physics-based radar simulator has been developed for Space Surveillance applications. This simulator is designed in a modular fashion, where each module describes a particular physical process or radar function (radio wave propagation & scattering, waveform generation, noise sources, etc.) involved in simulating the radar and its environment. For each of these modules, multiple versions are available in order to meet the end-users needs and requirements. For instance, the radar simulator supports different atmospheric models in order to facilitate different methods of simulating refraction of the radar beam. The radar model also has the capability to use highly accurate radar cross sections generated by the method of moments, accelerated by the fast multipole method. To accelerate this computationally expensive model, it is parallelized using MPI. As a testing framework for the radar model, it is incorporated into the Testbed Environment for Space Situational Awareness (TESSA). TESSA is based on a flexible, scalable architecture, designed to exploit high-performance computing resources and allow physics-based simulation of the SSA enterprise. In addition to the radar models, TESSA includes hydrodynamic models of satellite intercept and debris generation, orbital propagation algorithms, optical brightness calculations, optical system models, object detection algorithms, orbit determination algorithms, simulation analysis and visualization tools. Within this framework, observations and tracks generated by the new radar model are compared to results from a phenomenological radar model. In particular, the new model will be used to simulate an S-band upgrade to the space fence.

Horsley, M.; Fasenfest, B.

2010-09-01

407

Analysis and evaluation of a forward-viewing scanning radar scatterometer system  

E-print Network

at 265 KHz plus the doppler shift frequency around 250 KMz. The power loss, ampli- tier flucuations, and system noise could then be ac- counted for and corrected. The power split in the mixer would not occur. Signal Reduction and Logic Once... at 265 KHz plus the doppler shift frequency around 250 KMz. The power loss, ampli- tier flucuations, and system noise could then be ac- counted for and corrected. The power split in the mixer would not occur. Signal Reduction and Logic Once...

Arnold, Richard H

2012-06-07

408

Design and development of control software in the experiment system of synthetic aperture laser imaging radar  

NASA Astrophysics Data System (ADS)

A control software experiment system of synthetic aperture imaging ladar is developed based on multithreading parallel mechanism of Labview8.6 and SCPI (standard commands for programmable instruments) protocol. Firstly, hardware composition and software function requirement of the system are analyzed. Then, the control module of the laser and stepper motor and the data communication module of oscillograph are developed separately and the three modules are integrated to realize the gather and compute of the return signal. Finally, by the result of experiment, the control software worked steady and real timely and it can operate the laser, stepper motor and oscillograph successfully.

Wu, Yapeng; Zhou, Yu; Zhi, Ya'nan; Sun, Jianfeng; Lu, Wei; Liu, Liren

2010-08-01

409

Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) Applied in Optimization of Radiation Pattern Control of Phased-Array Radars for Rocket Tracking Systems  

PubMed Central

In launching operations, Rocket Tracking Systems (RTS) process the trajectory data obtained by radar sensors. In order to improve functionality and maintenance, radars can be upgraded by replacing antennas with parabolic reflectors (PRs) with phased arrays (PAs). These arrays enable the electronic control of the radiation pattern by adjusting the signal supplied to each radiating element. However, in projects of phased array radars (PARs), the modeling of the problem is subject to various combinations of excitation signals producing a complex optimization problem. In this case, it is possible to calculate the problem solutions with optimization methods such as genetic algorithms (GAs). For this, the Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) method was developed to control the radiation pattern of PAs. The GA-MMC uses a reconfigurable algorithm with multiple objectives, differentiated coding and a new crossover genetic operator. This operator has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, GA-MMC was successful in more than 90% of the tests for each application, increased the fitness of the final population by more than 20% and reduced the premature convergence. PMID:25196013

Silva, Leonardo W. T.; Barros, Vitor F.; Silva, Sandro G.

2014-01-01

410

Lectures on Radar Applications in Mesoscale Meteorology  

NSDL National Science Digital Library

This website provides access to the streaming presentations and PowerPoint source files for the 11 lectures delivered during the AMS Educational Forum âA Primer on Radar Analysis Techniques Used in Mesoscale Meteorologyâ held on 23 October 2005 in Albuquerque, NM. The presentations discuss how many advanced techniques for the analysis of meteorological radar data can be used to improve understanding of the structure, dynamics, and evolution of mesoscale circulations. The Forum was organized into four sections: 1) Microphysical Characterization of Precipitation Systems Using Dual-Polarization Radar Measurements, 2) Single Doppler Retrieval and Assimilation Techniques for Use in Mesoscale Models, 3) Analysis of Mesoscale Processes Using Wind Profiling Radars and Velocity Azimuth Display and 4) Airborne Doppler Radar Analysis of Tropical and Extratropical Mesoscale Systems.

Comet

2006-02-07

411

The method for radar signal recognition  

NASA Astrophysics Data System (ADS)

One of the principal functions of the ESM/ELINT system is gathering basic information from entire electromagnetic spectrum and its analysis. In most cases, based only on primary features of incoming radar signals, the modern electronic intelligence system cannot recognize the different devices of the same type or class. The radar signal is the source of information about recognized object, which is propagated into surrounding environment. Radar emitter identification based on a collection of received radar signals is a subject of wide interest in both civil and military applications. To classify radar emitters in the surrounding environment we need to explore the detailed structure inside each pulse. An emitter has its own electrical signal structure inside each of its transmitted pulses due to both intentional and unintentional modulations. It is very difficult work to perfectly employ a microwave sensors in the combat identification, because it is a composite task that involves pulse measurements, features extraction, normalization, selection, classification (recognition) and verification.

Kawalec, A.; Owczarek, R.

2006-11-01

412

Preprocessing: Geocoding of AVIRIS data using navigation, engineering, DEM, and radar tracking system data  

NASA Technical Reports Server (NTRS)

Remotely sensed data have geometric characteristics and representation which depend on the type of the acquisition system used. To correlate such data over large regions with other real world representation tools like conventional maps or Geographic Information System (GIS) for verification purposes, or for further treatment within different data sets, a coregistration has to be performed. In addition to the geometric characteristics of the sensor there are two other dominating factors which affect the geometry: the stability of the platform and the topography. There are two basic approaches for a geometric correction on a pixel-by-pixel basis: (1) A parametric approach using the location of the airplane and inertial navigation system data to simulate the observation geometry; and (2) a non-parametric approach using tie points or ground control points. It is well known that the non-parametric approach is not reliable enough for the unstable flight conditions of airborne systems, and is not satisfying in areas with significant topography, e.g. mountains and hills. The present work describes a parametric preprocessing procedure which corrects effects of flight line and attitude variation as well as topographic influences and is described in more detail by Meyer.

Meyer, Peter; Larson, Steven A.; Hansen, Earl G.; Itten, Klaus I.

1993-01-01

413

Microwave FMCW Doppler radar implementation for in-house pervasive health care system  

Microsoft Academic Search

In recent years, the research in the area of ubiquitous healthcare has intensified. There are many technological advances regarding the development of unobtrusive sensors for cardiac and respiratory activity, but the current scenario is still far away from an everyday life fulfilled with ubiquitous healthcare systems. In this paper, it is described the usage of 24GHz microwave FMCW (frequency modulated

Octavian Postolache; R. N. Madeira; P. S. Gira?o; Gabriela Postolache

2010-01-01

414

Synthetic aperture radar for a crop information system: A multipolarization and multitemporal approach  

Microsoft Academic Search

Acquisition of timely information is a critical requirement for successful management of an agricultural monitoring system. Crop identification and crop-area estimation can be done fairly successfully using satellite sensors operating in the visible and near-infrared (VIR) regions of the spectrum. However, data collection can be unreliable due to problems of cloud cover at critical stages of the growing season. The

Yifang Ban

1997-01-01

415

A coherent FM laser radar based system for remote metrology in ITER  

Microsoft Academic Search

The plasma facing surfaces in ITER must be aligned to millimeter accuracy with respect to the magnetic flux surfaces to prevent impurity influx into the plasma and to avoid component damage. Checking of in-vessel component alignment during initial assembly, operation, and subsequent maintenance is anticipated. A fully remote metrology system is necessary, particularly since major remote operations such as shield

R. E. Barry; T. W. Burgess; M. M. Menon; A. Slotwinski; R. Sebastian

1995-01-01

416

Improving Ground Penetrating Radar Imaging in High Loss Environments by Coordinated System Development, Data Processing, Numerical Modeling, & Visualization ...  

SciTech Connect

The Department of Energy has identified the location and characterization of subsurface contaminants and the characterization of the subsurface as a priority need. Many DOE facilities are in need of subsurface imaging in the vadose and saturated zones. This includes (1) the detection and characterization of metal and concrete structures, (2) the characterization of waste pits (for both contents and integrity) and (3) mapping the complex geological/hydrological framework of the vadose and saturated zones. The DOE has identified ground penetrating radar (GPR) as a method that can non-invasively map transportation pathways and vadose zone heterogeneity. An advanced GPR system and advanced subsurface modeling, processing, imaging, and inversion techniques can be directly applied to several DOE science needs in more than one focus area and at many sites. Needs for enhanced subsurface imaging have been identified at Hanford, INEEL, SRS, ORNL, LLNL, SNL, LANL, and many other sites. In fact, needs for better subsurface imaging probably exist at all DOE sites. However, GPR performance is often inadequate due to increased attenuation and dispersion when soil conductivities are high. Our objective is to extend the limits of performance of GPR by improvements to both hardware and numerical computation. The key features include (1) greater dynamic range through real time digitizing, receiver gain improvements, and high output pulser, (2) modified, fully characterized antennas with sensors to allow dynamic determination of the changing radiated waveform, (3) modified deconvolution and depth migration algorithms exploiting the new antenna output information, (4) development of automatic full waveform inversion made possible by the known radiated pulse shape.

Powers, Michael H.

2003-06-01

417

The evolution of total lightning and radar reflectivity characteristics of two mesoscale convective systems over Houston, Texas  

E-print Network

.1.2.2 Contoured Frequency by Altitude Diagrams (CFADs)............................41 2.1.2.3 Rainfall Totals ..........................................................................................42 2.2 Lightning Detection and Ranging Network....3 Time series plot of the mean reflectivities (dBZ) in three equally sized areas of the stratiform region ............................................................ 57 3.4 Contoured frequency by altitude diagrams (CFADs) and mean profiles of radar...

Hodapp, Charles Lee

2009-05-15

418

HF Radar Sounding of TIDs with the Use of the DPS System and Signals from Broadcasting Stations  

Microsoft Academic Search

Atmospheric gravity waves (AGW) propagating in the ionosphere produce quasiperiodic varia- tions of the ionospheric electron density, known as traveling ionospheric disturbances (TID). In its turn, these wavelike processes modulate parameters of the radio signals in the medium; this effect is widely used for the remote sensing of TIDs. For example, paper (1) presents a bistatic radar technique for recovering

V. S. Beley; V. G. Galushko; D. Paznukhov; B. W. Reinisch; Y. M. Yampolski

419

Radar augmentation device  

NASA Technical Reports Server (NTRS)

The radar augmentation device (RAD) serves to increase the radar response of a target body and thus expedite radar acquisition. The design and development of the RAD are discussed with particular emphasis on technical problems that were encountered and solved. Discussions of the mode of operation of the RAD and the ground test history are also included.

Riedel, J. K.

1972-01-01

420

Lunar radar backscatter studies  

NASA Technical Reports Server (NTRS)

The lunar surface material in the Plato area is characterized using Earth based visual, infrared, and radar signatures. Radar scattering in the lunar regolith with an existing optical scattering computer program is modeled. Mapping with 1 to 2 km resolution of the Moon using a 70 cm Arecibo radar is presented.

Thompson, T. W.

1979-01-01

421

Controlling radar signature  

SciTech Connect

Low observable technologies for military and tactical aircraft are reviewed including signature-reduction techniques and signal detection/jamming. Among the applications considered are low-signature sensors and the reduction of radar cross section in conjunction with radar-absorbing structures and materials. Technologies for reducing radar cross section are shown to present significant technological challenges, although they afford enhanced aircraft survivability.

Foulke, K.W. (U.S. Navy, Naval Air Warfare Center, China Lake, CA (United States))

1992-08-01

422

Controlling radar signature  

Microsoft Academic Search

Low observable technologies for military and tactical aircraft are reviewed including signature-reduction techniques and signal detection\\/jamming. Among the applications considered are low-signature sensors and the reduction of radar cross section in conjunction with radar-absorbing structures and materials. Technologies for reducing radar cross section are shown to present significant technological challenges, although they afford enhanced aircraft survivability.

Foulke

1992-01-01

423

Radar hydrology: rainfall estimation  

Microsoft Academic Search

Radar observations of rainfall and their use in hydrologic research provide the focus for the paper. Radar-rainfall products are crucial for input to runoff and flood prediction models, validation of satellite remote sensing algorithms, and for statistical characterization of extreme rainfall frequency. In this context we discuss the issues of radar-rainfall product development, and the theoretical and practical requirements of

W. F. Krajewski; J. A. Smith

2002-01-01

424

Synchronization in spread spectrum laser radar systems based on PMD-DLL  

NASA Astrophysics Data System (ADS)

This paper proposes a new optoelectronic delay locked loop (OE-DLL) and its use in optical ranging systems. The so called PMD-DLL receiver module is based on a novel electro-optical modulator (EOM), called the Photonic Mixer Device (PMD). This sensor element is a semiconductor device, which combines fast optical sensing and mixing of incoherent light signals in one component part by its unique and powerful principle of operation. Integration of some simple additional on-chip components offers a high integrated electro-optical correlation unit. Simulations and experimental results have already impressively verified the operation principle of PMD structures, all realized in CMOS technology so far. Although other technologies are also promising candidates for the PMD realization they should not be further discussed in this contribution. The principle of the new DLL approach is intensively discussed in this paper. Theoretical analysis as well as experimental results of a realized PMD-DLL system are demonstrated and judged. Due to the operation principle of sophisticated PMD devices and their unique features, a correlation process may be realized in order to synchronize a reflected incoherent light wave with an electronic reference signal. The phase shift between both signals represents the distance to an obstacle and may be determined by means of the synchronization process. This new approach, avoiding so far needed critical components such as broadband amplifiers and mixers for the detection of small photo currents in optical distance measurement, offers an extremely fast and precise phase determination in ranging applications based on the time- of-flight (TOF) principle. However, the optical measurement signal may be incoherent -- therefore a laser source is not needed imperatively. The kind of waveform used for the modulation of the light signal is variable and depends on the demands of every specific application. Even if there are plenty other alternatives (e.g., heterodyne techniques), in this contribution only so called quasi-heterodyne techniques - - also known as phase shifting methods -- are discussed and used for the implementation. The light modulation schemes described in this contribution are square-wave as well as pseudo-noise modulation. The latter approach, inspired by the wide spread use in communication as well as in position detection (e.g., IS-95 and GPS), offers essential advantages and is the most promising modulation method for the ranging approach. So called CDMA (code division multiple access) systems form a major task in communication technology investigations since the third generation mobile phone standard is also partly based on this principle. Fast and reliable synchronization in direct sequence spread spectrum communication systems (DSSS) differs hardly from the already mentioned ranging approach and will also be discussed. The possibility to integrate all components in a monolithic PMD based DLL design is also presented and discussed. This method might offer the feature to integrate complete lines or matrixes of PMD based DLLs for highly parallel, multidimensional ranging. Finally, an outlook is given with regard to further optimized PMD front ends. An estimation of the expected characteristics concerning accuracy and speed of the distance measurement is given in conclusion.

Buxbaum, Bernd; Schwarte, Rudolf; Ringbeck, Thorsten; Luan, Xuming; Zhang, Zhigang; Xu, Zhanping; Hess, H.

2000-09-01

425

CLASSIFICATION AND CHARACTERIZATION OF TROPICAL PRECIPITATION BASED ON HIGH-RESOLUTION AIRBORNE VERTICAL-INCIDENCE RADAR  

E-print Network

,231 km of flight tracks over tropical precipitation systems . . The radar, the ER-2 Doppler radar (EDOP on the Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar V-method (NASDA 1999). Fig 1. Flowchart AND VERTICAL VELOCITY PROFILES The TRMM Precipitation Radar (PR) vertical resolution is 250 m, at least

Geerts, Bart

426

Use of imaging radar for geology and archeology  

NASA Technical Reports Server (NTRS)

Imaging radar is shown to be a useful sensor for geological analysis as a standal one sensor in clouded regions or as a complementary data source with visible NIR systems. Radar image tone is a function of the radar system parameters (imaging geometry, frequency, polarization) and a function of the target (local slope, electrical properties, and surface roughness). Substantial topographic texture enhancement can be achieved for large scale features by using specular returns associated with steep-incidence radars or shadows associated with grazing-incidence systems. Texture enhancement also allows radar to image lineaments and archeological features, such as canals and causeways. Future multispectral radars may achieve better discrimination of subresolution structures. Seasat radar images of several geographic locations are provided.

Daily, M.

1981-01-01

427

Application of radar for automotive collision avoidance. Volume 2: Development plan and progress reports  

NASA Technical Reports Server (NTRS)

The purpose of this project was research and development of an automobile collision avoidance radar system. Items within the scope of the one-year effort were to: (1) review previous authors' work in this field; (2) select a suitable radar approach; (3) develop a system design; (4) perform basic analyses and observations pertinent to radar design, performance, and effects; (5) fabricate and collect radar data from a data collection radar; (6) analyze and derive conclusions from the radar data; and (7) make recommendations about the likelihood of success of the investigated radar techniques. The final technical report presenting all conclusions is contained in Volume 1.

Lichtenberg, Christopher L. (editor)

1987-01-01

428

SMAP RADAR Processing and Calibration  

NASA Astrophysics Data System (ADS)

The Soil Moisture Active Passive (SMAP) mission uses L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This presentation will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation. To obtain the desired high spatial resolution the level 1 radar ground processor employs synthetic aperture radar (SAR) imaging techniques. Part of the challenge of the SMAP data processing comes from doing SAR imaging on a conically scanned system with rapidly varying squint angles. The radar echo energy will be divided into range/Doppler bins using time domain processing algorithms that can easily follow the varying squint angle. For SMAP, projected range resolution is about 250 meters, while azimuth resolution varies from 400 meters to 1.2 km. Radiometric calibration of the SMAP radar means measuring, characterizing, and where necessary correcting the gain and noise contributions from every part of the system from the antenna radiation pattern all the way to the ground processing algorithms. The SMAP antenna pattern will be computed using an accurate antenna model, and then validated post-launch using homogeneous external targets such as the Amazon rain forest to look for uncorrected gain variation. Noise subtraction is applied after image processing using measurements from a noise only channel. Variations of the internal electronics are tracked by a loopback measurement which will capture most of the time and temperature variations of the transmit power and receiver gain. Long-term variations of system performance due to component aging will be tracked and corrected using stable external reference targets. Candidate targets include the Amazon rain forest and a model-corrected global ocean measurement. Radio frequency interference (RFI) signals are expected in the L-band frequency window used by the SMAP radar because many other users also operate in this band. Based on results of prior studies at JPL, SMAP L1 radar processing will use a "Slow-time thresholding" or STT algorithm to handle RFI contamination. The STT technique looks at the slow-time series associated with a given range sample, sets an appropriate threshold, and identifies any samples that rise above this threshold as RFI events. The RFI events are removed and the data are azimuth compressed without those samples. Faraday rotation affects L-band signals by rotating the polarization vector during propagation through the ionosphere. This mixes HH, VV, HV, and VH results with each other introducing another source of error. The SMAP radar is not fully polarimetric so the radar data do not provide a correction by themselves. Instead a correction must be derived from other sources. L1 radar processing will use estimates of Faraday rotation derived from externally supplied GPS-based measurements of the ionosphere total electron content (TEC). This work is supported by the SMAP project at the Jet Propulsion Laboratory, California Institute of Technology.

West, R. D.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M. J.

2013-12-01

429

The Radar Image Generation (RIG) model  

NASA Technical Reports Server (NTRS)

RIG is a modeling system which creates synthetic aperture radar (SAR) and inverse SAR images from 3-D faceted data bases. RIG is based on a physical optics model and includes the effects of multiple reflections. Both conducting and dielectric surfaces can be modeled; each surface is labeled with a material code which is an index into a data base of electromagnetic properties. The inputs to the program include the radar processing parameters, the target orientation, the sensor velocity, and (for inverse SAR) the target angle rates. The current version of RIG can be run on any workstation, however, it is not a real-time model. We are considering several approaches to enable the program to generate realtime radar imagery. In addition to its image generation function, RIG can also generate radar cross-section (RCS) plots as well as range and doppler radar return profiles.

Stenger, Anthony J.

1993-01-01

430

Progress in coherent laser radar  

Microsoft Academic Search

Considerable progress with coherent laser radar has been made over the last few years, most notably perhaps in the available range of high performance devices and components and the confidence with which systems may now be taken into the field for prolonged periods of operation. Some of this increasing maturity was evident at the 3rd Topical Meeting on Coherent Laser

J. M. Vaughan

1986-01-01

431

Radar Technology for Mine Detection  

Microsoft Academic Search

Much attention is being given to the challenge of detecting buried non-metallic mines and National and International programmes are underway to develop more effective detection and clearance systems. Reported results from the US national programmes on mine detection suggest that radar can outperform conventional metal detectors, which only respond to the metal content of a mine and hence are insensitive

D J Daniels; C Martel

2001-01-01

432

Performance assessment criteria for OTH radar  

NASA Astrophysics Data System (ADS)

While most aspects of the performance of such over-the-horizon (OTH) systems as Australia's Jindalee Operational Radar Network are expressible in conventional parameters, these parameters do not usually express results in the form required by automated high-level decision-makers. The present approach is to use a 'top-down' method; fuzzy logic is shown to be useful in furnishing a linguistic statement concerning the system performance of an OTH radar system.

Kewley, D. J.; dall, I. W.

433

European firms target development of bistatic radar  

NASA Astrophysics Data System (ADS)

European R&D organizations are actively pursuing bistatic radar systems in virtue of their ECM-related advantages. In bistatic systems, the vulnerability of the passive, covert receiver to direct attack is substantially reduced; bistatic receivers can operate with target illuminations furnished by several monostatic radars or by dedicated mobile illuminators. Attention is being given to the problem of transmitter/receiver synchronization, which governs system sensitivity, resolution, accuracy, reliability, response time, and directivity. Terrain-related effects are also noted.

Mitchell, Bill

1988-03-01

434

Highly Integrated Radar Sensor-on-Chip  

NASA Astrophysics Data System (ADS)

A highly integrated 24 GHz radar sensor is presented, based on a Radio Frequency Integrated Circuit (RFIC) which was specifically developed for a Frequency Modulated Shift Keying (FMSK) based Radar system design. Antenna, waveform, the Radio Frequency (RF) and Digital Signal Processor (DSP) module, the software design, cost and performance aspects will be described. The significant technical and economical advantages of the implemented Silicon-Germanium (SiGe) Bipolar CMOS (BiCMOS) transceiver are demonstrated. Some automotive and other applications based on this technology and new radar system design will be explained.

Mende, Ralph

2012-05-01

435

A Bayesian technique for conditioning radar precipitation estimates to rain-gauge measurements Hydrology and Earth System Sciences, 5(2), 187199 (2001) EGS  

E-print Network

A Bayesian technique for conditioning radar precipitation estimates to rain-gauge measurements 187 precipitation estimates to rain-gauge measurements Ezio Todini Department of Earth and Geo sense, areal precipitation fields estimated from meteorological radar to point measurements

Paris-Sud XI, Université de

436

Research on CO2 laser radar imaging experiment  

Microsoft Academic Search

The laser radar is a radar system adopting laser photosource and operating on optical band and the laser heterodyne measurement is a detection technique with high sensitivity. Optical system plays an important role in heterodyne detection system. The reasonable selection of performance parameters of optical system has direct influence upon the ability of system to detect objects. The characteristics of

Hai-yan Li; Min Zhu; Yan-zhi Dong

2008-01-01

437

An estimation and verification of vessel radar-cross-sections for HF surface wave radar  

Microsoft Academic Search

The radar cross sections (RCS) of both small and large ships for High Frequency Surface Wave Radar (HFSWR) were studied by using Numerical Electromagnetics Code and by using measurements from a HFSWR system at Cape Race, Newfoundland, Canada. The results of the study indicate that Teleost, a 2405-ton Canadian Coast Guard ship, and large cargo-container vessels (?36000 ton) have comparable

Harold Wilson; Hank Leong

2003-01-01

438

P15R.1 THE DETECTABILITY OF TORNADIC SIGNATURES WITH DOPPLER RADAR: A RADAR EMULATOR STUDY  

E-print Network

time series of radar data by combining the simulated returns from individual hydrometeors within The design of a weather radar system, as well as its scanning strategies, involves various tradeoffs based upon the goal of observing certain features of interest. The tradeoffs made in this design are based

Xue, Ming

439

Pedestrian recognition using automotive radar sensors  

NASA Astrophysics Data System (ADS)

The application of modern series production automotive radar sensors to pedestrian recognition is an important topic in research on future driver assistance systems. The aim of this paper is to understand the potential and limits of such sensors in pedestrian recognition. This knowledge could be used to develop next generation radar sensors with improved pedestrian recognition capabilities. A new raw radar data signal processing algorithm is proposed that allows deep insights into the object classification process. The impact of raw radar data properties can be directly observed in every layer of the classification system by avoiding machine learning and tracking. This gives information on the limiting factors of raw radar data in terms of classification decision making. To accomplish the very challenging distinction between pedestrians and static objects, five significant and stable object features from the spatial distribution and Doppler information are found. Experimental results with data from a 77 GHz automotive radar sensor show that over 95% of pedestrians can be classified correctly under optimal conditions, which is compareable to modern machine learning systems. The impact of the pedestrian's direction of movement, occlusion, antenna beam elevation angle, linear vehicle movement, and other factors are investigated and discussed. The results show that under real life conditions, radar only based pedestrian recognition is limited due to insufficient Doppler frequency and spatial resolution as well as antenna side lobe effects.

Bartsch, A.; Fitzek, F.; Rasshofer, R. H.

2012-09-01

440

Theoretical investigation of the applicability of a dual-frequency radar system to the study of convective liquid precipitation  

E-print Network

interval of diameters from a to atda. The element of volume sampled by the radar may be written as Red+1. Integration of [19] over the total volume of scatterers and in range over half the pulse length, h, gives Rib/a P f&P?== ~~r" j ~ f. m)z(sar)Ja J... interval of diameters from a to atda. The element of volume sampled by the radar may be written as Red+1. Integration of [19] over the total volume of scatterers and in range over half the pulse length, h, gives Rib/a P f&P?== ~~r" j ~ f. m)z(sar)Ja J...

Von, Vernon Mow Hing

2012-06-07

441

2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

442

A complementary filtering technique for deriving aircraft velocity and position information. [onboard navigation system and radar tracking signals for instrument landing approach guidance  

NASA Technical Reports Server (NTRS)

An onboard navigation system which employed complementary filtering was developed to provide velocity and position information. The inputs to the mix filter included both acceleration inputs, which provided high-frequency position and velocity information, and radar position inputs, which provided the low-frequency position and velocity information. Onboard aircraft instrumentation, including attitude reference gyros and body-mounted accelerometers, was used to provide the acceleration information. An in-flight comparison of signal quality and accuracy showed good agreement between the complementary filtering system and an aided inertial navigation system. Furthermore, the complementary filtering system was proven to be satisfactory in control and display system applications for both automatic and pilot-in-the-loop instrument approaches and landings.

Niessen, F. R.

1975-01-01

443

Imaging radar for bridge deck inspection  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL)l is developing a prototype imaging radar for inspecting steel reinforced concrete bridge decks. The system is designed to acquire Synthetic Aperture Radar (SAR) data and provide high-resolution images of internal structure, flaws, and defects enabling bridge inspectors to nondestructively evaluate and characterize bridge deck condition. Concrete delamination resulting from corrosion of steel reinforcing bars (rebars) is an important structural defect that the system is designed to detect. The prototype system uses arrays of compact, low-cost Micropower Impulse Radar (MIR) modules, supported by appropriate data acquisition and storage subsystems, to generate and collect the radar data, and unique imaging codes to reconstruct images of bridge deck internals. In this paper, we provide an overview of the prototype system concept, discuss its expected performance, and present recent experimental results showing the capability of this approach to detect thin delamination simulations embedded in concrete.

Warhus, J.; Mast, J.; Nelson, S.

1995-04-13

444

Imaging radar for bridge deck inspection  

NASA Astrophysics Data System (ADS)

Lawrence Livermore National Laboratory is developing a prototype imaging radar for inspecting steel reinforced concrete bridge decks. The system is designed to acquire synthetic aperture radar data and provide high-resolution images of internal structure, flaws, and defects enabling bridge inspectors to nondestructively evaluate and characterized bridge deck condition. Concrete delamination resulting from corrosion of steel reinforcing bars (rebars) is an important structural defect that the system is designed to detect. The prototype system uses arrays of compact, low-cost micropower impulse radar (MIR) modules, supported by appropriate data acquisition and storage subsystems, to generate and collect the radar data, and unique imaging codes to reconstruct images of bridge deck internals. In this paper, we provide an overview of the prototype system concept, discuss its expected performance, and present recent experimental results showing the capability of this approach to detect thin delamination simulations embedded in concrete.

Warhus, John P.; Mast, Jeffrey E.; Nelson, Scott D.

1995-05-01

445

Transverter Assembly for the Advanced Instrumentation Radar.  

National Technical Information Service (NTIS)

This report presents a physical description of the S84789 Transverter Assembly which is part of the Advanced Instrument Radar Relay System. The environmental and electrical requirements are also provided along with the descriptions and results of evaluati...

J. M. Simons

1988-01-01

446

Assimilation of Doppler weather radar observations in a mesoscale model for the prediction of rainfall associated with mesoscale convective systems  

Microsoft Academic Search

Obtaining an accurate initial state is recognized as one of the biggest challenges in accurate model prediction of convective\\u000a events. This work is the first attempt in utilizing the India Meteorological Department (IMD) Doppler radar data in a numerical\\u000a model for the prediction of mesoscale convective complexes around Chennai and Kolkata. Three strong convective events both\\u000a over Chennai and Kolkata

S. Abhilash; Someshwar Das; S. R. Kalsi; M. Das Gupta; K. Mohankumar; J. P. George; S. K. Banerjee; S. B. Thampi; D. Pradhan

2007-01-01

447

Geophysical assessment of the hydraulic property of the fracture systems around Lake Nasser-Egypt: In sight of polarimetric borehole radar  

NASA Astrophysics Data System (ADS)

Hydraulic property of the subsurface structures is a complicated mission. In this work, the polarimetric analysis for the measured dataset applied by the polarimetric borehole radar system in order to delineate the characteristics of subsurface fractures. Two different locations in USA and Egypt were selected to perform our investigation. The first polarimetric dataset has been acquired at Mirror Lake, USA which is well known as a standard site for testing the hydraulic properties of subsurface fractures (Sato et al., 1999). The results show the presence of nine fracture zones in one borehole FSE-1. The hydraulic properties were detected and the subsurface fractures were differentiated into four categories fracture zones after deriving the radar polarimetric analysis of alpha, entropy and anisotropy parameters at 30 MHz frequency. The fracture zones at 24.75, 47.8 and 55.2 m depths have the highest hydraulic transmissivity while the fracture zones at 28.5, 36.15 m have the lowest hydraulic transmissivity. These results show a good consistency with the hydraulic permeability tracer test and the structures exist in the area. Similarly, we used the same technique to characterize the subsurface fracture systems detected by geoelectric and geomagnetic methods around Lake Nasser in Egypt using the previous results of Mirror Lake as a key guide. The results show a great correlation with detected structures prevailed in the sedimentary and basement rocks. These results illustrate an ideal explanation for the prevailed subsurface structures and the recharging of the main Nubian sandstone aquifer from Lake Nasser. Also, these results also show that the northeast fracture zone trends are most probably having the highest hydraulic transmissivity whereas the northwest fracture zones have the lowest one. The integration of surface geophysical measurements with the polarimetric borehole radar and the polarimetric analysis of its datasets introduce better understanding of the recharging mechanism between surface water and the subsurface aquifer and also can be used as clue for identifying the subsurface structures for different areas.

Mansour, Khamis; Basheer, Alhussein A.; Rabeh, Taha; Khalil, Ahmed; Eldin, A. A. Essam; Sato, Motoyuki

2014-06-01

448

Target detection and positioning in correlated scattering using widely distributed MIMO radar  

Microsoft Academic Search

Multiple-input multiple-output (MIMO) radars use different sources of diversity to improve the performance of the radar. A MIMO radar in which angular diversity is achieved by using widely distributed antennas has been proposed to reduce the impact of the fluctuations of the target radar cross-section. This type of system is also known as the statistical MIMO radar. Typically, it has

T. Aittomaki; Visa Koivunen

2010-01-01

449

Radar/radiometer facilities for precipitation measurements  

NASA Technical Reports Server (NTRS)

The OSU ElectroScience Laboratory Radar/Radiometer Facilities are described. This instrumentation includes a high-resolution radar/radiometer system, a fully automated low-resolution radar system, and a small surveillance radar system. The high-resolution radar/radiometer system operates at 3, 9, and 15 GHz using two 9.1 m and one 4.6 m parabolic antennas, respectively. The low-resolution and surveillance radars operate at 9 and 15 GHz, respectively. Both the high- and low-resolution systems are interfaced to real-time digital processing and recording systems. This capability was developed for the measurement of the temporal and spatial characteristics of precipitation in conjunction with millimeter wavelength propagation studies utilizing the Advanced Technology Satellites. Precipitation characteristics derived from these measurements could also be of direct benefit in such diverse areas as: the atmospheric sciences, meteorology, water resources, flood control and warning, severe storm warning, agricultural crop studies, and urban and regional planning.

Hodge, D. B.; Taylor, R. C.

1973-01-01

450

CloudSat as a Global Radar Calibrator  

SciTech Connect

The calibration of the CloudSat spaceborne cloud radar has been thoroughly assessed using very accurate internal link budgets before launch, comparisons with predicted ocean surface backscatter at 94 GHz, direct comparisons with airborne cloud radars, and statistical comparisons with ground-based cloud radars at different locations of the world. It is believed that the calibration of CloudSat is accurate to within 0.5 to 1 dB. In the present paper it is shown that an approach similar to that used for the statistical comparisons with ground-based radars can now be adopted the other way around to calibrate other ground-based or airborne radars against CloudSat and / or detect anomalies in long time series of ground-based radar measurements, provided that the calibration of CloudSat is followed up closely (which is the case). The power of using CloudSat as a Global Radar Calibrator is demonstrated using the Atmospheric Radiation Measurement cloud radar data taken at Barrow, Alaska, the cloud radar data from the Cabauw site, The Netherlands, and airborne Doppler cloud radar measurements taken along the CloudSat track in the Arctic by the RASTA (Radar SysTem Airborne) cloud radar installed in the French ATR-42 aircraft for the first time. It is found that the Barrow radar data in 2008 are calibrated too high by 9.8 dB, while the Cabauw radar data in 2008 are calibrated too low by 8.0 dB. The calibration of the RASTA airborne cloud radar using direct comparisons with CloudSat agrees well with the expected gains and losses due to the change in configuration which required verification of the RASTA calibration.

Protat, Alain; Bouniol, Dominique; O'Connor, E. J.; Baltink, Henk K.; Verlinde, J.; Widener, Kevin B.

2011-03-01

451

3. VIEW NORTHWEST, height finder radar towers, and radar tower ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

452

Evaluation of atmospheric turbulence, energy exchanges and structure of convective cores during the occurrence of mesoscale convective systems using MST radar facility at Gadanki  

NASA Astrophysics Data System (ADS)

Mesoscale convective systems (MCSs) wreak lots of havoc and severe damage to life and property due to associated strong gusty winds, rainfall and hailstorms even though they last for an hour or so. Planetary boundary layer (PBL) plays an important role in the transportation of energy such as momentum, heat and moisture through turbulence into the upper layers of the atmosphere and acts as a feedback mechanism in the generation and sustenance of MCS. In the present study, three severe thunderstorms that occurred over mesosphere-stratosphere-troposphere (MST) radar facility at National Atmospheric Research Laboratory (NARL), Gadanki, India, have been considered to understand turbulence, energy exchanges and wind structure during the different epochs such as pre-, during and after the occurrence of these convective episodes. Significant changes in the turbulence structure are noticed in the upper layers of the atmosphere during the thunderstorm activity. Identified strong convective cores with varying magnitudes of intensity in terms of vertical velocity at different heights in the atmosphere discern the presence of shallow as well as deep convection during initial, mature and dissipative stages of the thunderstorm. Qualitative assessments of these convective cores are verified using available Doppler Weather Radar imageries in terms of reflectivity. The MST radar derived horizontal wind profiles are in good comparison with observed radiosonde winds. Significant variations in the surface meteorological parameters, sensible heat flux and turbulent kinetic energy as well as horizontal wind profiles are noticed during the different epochs of the convective activity. This work is useful in evaluating the performance of PBL schemes of mesoscale models in simulating MCS.

Satyanarayana, A. N. V.; Sultana, Sabiha; Narayana Rao, T.; Satheesh Kumar, S.

2014-06-01

453

Space-based radar clutter cancellation techniques  

NASA Astrophysics Data System (ADS)

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent upon the clutter cancellation technique employed. In this paper, radar clutter is described using temporal probability models, spectral models, and average backscatter coefficient models. Capitalizing on the different spectral characteristics between clutter and targets, three representative Doppler clutter cancellation schemes are described. Using the clutter models and cancellation schemes described, the clutter attenuation factors for the various cancellation methods against different backgrounds are computed to evaluate the clutter cancellation ability of different cancellation schemes.

Devenuto, J.; Castor, K. G.

454

Space Radar Image of Baikal Lake, Russia  

NASA Technical Reports Server (NTRS)

This is an X-band black-and-white image of the forests east of the Baikal Forest in the Jablonowy Mountains of Russia. The image is centered at 52.5 degrees north latitude and 116 degrees east longitude near the mining town of Bukatschatscha. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on October 4, 1994, during the second flight of the spaceborne radar. This area is part of an international research project known as the Taiga Aerospace Investigation using Geographic Information System Applications.

1994-01-01

455

Planetary radar studies  

NASA Technical Reports Server (NTRS)

A catalog of lunar and radar anomalies was generated to provide a base for comparison with Venusian radar signatures. The relationships between lunar radar anomalies and regolith processes were investigated, and a consortium was formed to compare lunar and Venusian radar images of craters. Time was scheduled at the Arecibo Observatory to use the 430 MHz radar to obtain high resolution radar maps of six areas of the lunar suface. Data from 1978 observations of Mare Serenitas and Plato are being analyzed on a PDP 11/70 computer to construct the computer program library necessary for the eventual reduction of the May 1981 and subsequent data acquisitions. Papers accepted for publication are presented.