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Fully polarized Xpatch signatures are transformed to two left circularly polarized signals. These two signals are then filtered by a linear FM pulse compression ('chirp') transfer function, corrupted by AWGN, and filtered by a filter matched to the 'chirp' transfer function. The bandwidth of the 'chirp' radar is about 750 MHz. Range profile feature extraction is performed using the TLS Prony Model parameter estimation technique developed at Ohio State University. Using the Prony Model, each scattering center is described by a polarization ellipse, relative energy, frequency response, and range. This representation of the target is vector quantized using a K-means clustering algorithm. Sequences of vector quantized scattering centers as well as sequences of vector quantized range profiles are used to synthesize target specific Hidden Markov Models (HMM's). The identification decision is made by determining which HMM has the highest probability of generating the unknown sequence. The data consist of synthesized Xpatch signatures of two targets which have been difficult to separate with other RTI algorithms. The RTI algorithm developed for this thesis is clearly able to separate these two targets over a 10 by 10 degree (1 degree granularity) aspect angle window off the nose for SNRs as low as 0 dB. The classification rate is 100 % for SNRs of 5 - 20 dB, 95 % for a SNR of 0 dB and it drops rapidly for SNRs lower than 0 dB.

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Pulse compression techniques are studied which are applicable to a satellite altimeter having a topographic resolution of + 10 cm. A systematic design procedure is used to determine the system parameters. The performance of an optimum, maximum likelihood processor is analysed, which provides the basis for modifying the standard split-gate tracker to achieve improved performance. Bandwidth considerations lead to the recommendation of a full deramp STRETCH pulse compression technique followed by an analog filter bank to separate range returns. The implementation of the recommended technique is examined.

An approach is described for retrieving surface soil moisture and freeze/thaw state using 3-km resolution L-band radar data of the planned Soil Moisture Active and Passive (SMAP) mission. SMAP radar backscatter coefficients are simulated using radar scattering models and land surface hydrology model output generated over the contiguous United States (CONUS). A Monte-Carlo simulation is performed to assess the error budget of the soil moisture retrievals in the presence of radar measurement error and error in surface roughness. The estimated soil moisture retrieval accuracy is better than 0.06 cm3/cm3 for vegetation water content less than 1.2 kg/m2 and soil moisture in the range of 0 to 0.3 cm3/cm3. The retrieval performance improves if radar speckle is reduced by additional observations (e.g., including both fore- and aft-scan data). It is currently assumed that the surface roughness is known with 10% error, but a timeseries method is under development to estimate the roughness. The surface freeze/thaw state retrieval is simulated using a surface hydrology process model forced with climatology. The simulation illustrates a SMAP daily composite freeze/thaw product derived using a time-series algorithm applied to the SMAP high-resolution radar data.

The proposed work is in direct support of the Office of Naval Research's Transparent Urban Structures (TUS) program. The objective of the TUS program is to improve the collection, understanding, and dissemination of intelligence for the urban conflict. Through TUS, ONR seeks to develop technology which assists the warfighter in understanding the urban terrain of interest by detecting and classifying threats, both inside buildings and underground, and by maximizing situational awareness inside structures. The key focus of TUS is to develop advanced technologies that make urban man-made structures transparent, thereby eliminating the safe harbor that buildings provide to hostile forces and their malicious activities.

Previous radar mappings of the Moon at 70 cm wavelength in the late 1960's by Thompson have been replaced with a new set of observations using the 430 MHz radar at the Arecibo Observatory, Puerto Rico. Radar resolution was reduced to 2 to 5 km radar cell size and a beam-sweep, limb-to-limb calibration was conducted. Advances in computer technology provided the principle means of improving lunar radar mapping at this wavelength. Observation techniques and data processing are described and scattering differences found in the orthographic projection of the radar data are discussed.

A design study for a high resolution meteor radar system is carried out with the objective of measuring upper atmospheric winds and particularly studying short period atmospheric waves in the 80 to 120 km altitude region. The transmitter that is to be used emits a peak power of 4 Mw. The system is designed to measure the wind velocity and height of a meteor trail very accurately. This is achieved using a specially developed digital reduction procedure to determine wind velocity and range together with an interferometer for measuring both the azimuth and elevation angles of the region with a long baseline vernier measurement being used to refine the elevation angle measurement. The resultant accuracies are calculated to be + or - 0.9 m/s for the wind, + or - 230 m for the range and + or - 0.12 deg for the elevation angle, giving a height accuracy of + or - 375 m. The prospects for further development of this system are also discussed.

Bell System Technical Journal, 39: 4 July 1960 pp 809-820. The Design of Radar Signals Having Both High Range Resolution and High Velocity Resolution (Klauder, J.R.)

In this performing period, we have focused on radar imaging with the synchronized RF link. Specifically, after synchronizing, we fix the slave node, and move the master node smoothly, collecting raw correlator output continuously. From the starting and stopping time of the master motion, and the known distance, we estimate the relative master and slave positions in 2D (Figure 1). These positions, and the correlator outputs are combined in a backprojection algorithm to form a radar image of the surroundings (Figure 2).

In this period of performance, we are continuing to develop the radar design, software, and software for the final demonstration. We are also ordering and building the final demonstration hardware.

High range resolution can be obtained using a number of methods including ultra-wideband radar, intrapulse pulse compression, and super- resolution techniques. This thesis investigates the achievement of high radar range resolution by means of the step frequency waveform. The key advantage of the step frequency approach compared to other methods is the wide total bandwidth resulting in high range resolution while still maintaining a narrow instantaneous bandwidth which eases A/D sampling requirements. The effects of various waveform parameters on the high resolution range profile are determined for both noise and clutter limited environments. A novel technique is developed which enhances the resolution of moving targets in clutter and estimates the target velocity. This method consists of clutter cancellation followed by successive velocity compensations. Finally, design methods are developed to optimize system performance in a low PRF mode for both noise and clutter limited environments. Step frequency radar, Stepped-frequency waveform, High resolution radar, HRR.

The lunar regolith will most likely be a primary raw material for lunar base construction and resource extraction. High-resolution radar observations of the Moon provide maps of radar backscatter that have intensity variations generally controlled by the local slope, material, and structural properties of the regolith. The properties that can be measured by the radar system include the dielectric constant, density, loss tangent, and wavelength scale roughness. The radar systems currently in operation at several astronomical observatories provide the ability to image the lunar surface at spatial resolutions approaching 30 m at 3.8 cm and 12.6 cm wavelengths and approximately 500 m at 70 cm wavelength. The radar signal penetrates the lunar regolith to a depth of 10-20 wavelengths so the measured backscatter contains contributions from the vacuum-regolith interface and from wavelength-scale heterogeneities in the electrical properties of the subsurface material. The three wavelengths, which are sensitive to different scale structures and scattering volumes, provide complementary information on the regolith properties. Aims of the previous and future observations include (1) analysis of the scattering properties associated with fresh impact craters, impact crater rays, and mantled deposits; (2) analysis of high-incidence-angle observations of the lunar mare to investigate measurement of the regolith dielectric constant and hence porosity; (3) investigation of interferometric techniques using two time-delayed observations of the same site, observations that require a difference in viewing geometry less than 0.05 deg and, hence, fortuitous alignment of the Earth-Moon system when visible from Arecibo Observatory.

As part of an effort to further understand the geologic utility of radar studies of the terrestrial planets, investigators at the Hawaii Institute of Geophysics are collaborating with NEROC Haystack Observatory, MIT and the Jet Propulsion Laboratory in the analysis of existing 3.8 and 70 cm radar images of the Moon, and in the acquisition of new data for selected lunar targets. The intent is to obtain multi-polarization radar images at resolutions approaching 75 meters (3.8 cm wavelength) and 400 meters (70 cm wavelength) for the Apollo landing sites (thereby exploiting available ground truth) or regions covered by the metric camera and geochemical experiments onboard the command modules of Apollos 15, 16 and 17. These data were collected in both like- and cross-polarizations, and, in the case of the 70 cm data, permit the phase records to be used to assess the scattering properties of the surface. The distribution of surface units on the Moon that show a mismatch between the surface implied by like- and cross-polarized scattering data is being analyzed, based on the scattering models of Evans and Hagfors.

In this paper, TRMM (Tropical Rainfall Measuring Mission Satellite) Precipitation Radar (PR) products are evaluated by means of simultaneous comparisons with data from the high-altitude ER-2 Doppler Radar (EDOP), as well as ground-based radars. The comparison is aimed primarily at the vertical reflectivity structure, which is of key importance in TRMM rain type classification and latent heating estimation. The radars used in this study have considerably different viewing geometries and resolutions, demanding non-trivial mapping procedures in common earth-relative coordinates. Mapped vertical cross sections and mean profiles of reflectivity from the PR, EDOP, and ground-based radars are compared for six cases. These cases cover a stratiform frontal rainband, convective cells of various sizes and stages, and a hurricane. For precipitating systems that are large relative to the PR footprint size, PR reflectivity profiles compare very well to high-resolution measurements thresholded to the PR minimum reflectivity, and derived variables such as bright band height and rain types are accurate, even at high PR incidence angles. It was found that for, the PR reflectivity of convective cells small relative to the PR footprint is weaker than in reality. Some of these differences can be explained by non-uniform beam filling. For other cases where strong reflectivity gradients occur within a PR footprint, the reflectivity distribution is spread out due to filtering by the PR antenna illumination pattern. In these cases, rain type classification may err and be biased towards the stratiform type, and the average reflectivity tends to be underestimated. The limited sensitivity of the PR implies that the upper regions of precipitation systems remain undetected and that the PR storm top height estimate is unreliable, usually underestimating the actual storm top height. This applies to all cases but the discrepancy is larger for smaller cells where limited sensitivity is compounded by incomplete beam filling. Users of level three TRMM PR products should be aware of this scale dependency.

In this paper, TRMM (Tropical Rainfall Measuring Mission Satellite) Precipitation Radar (PR) products are evaluated by means of simultaneous comparisons with data from the high-altitude ER-2 Doppler Radar (EDOP), as well as ground-based radars. The comparison is aimed primarily at the vertical reflectivity structure, which is of key importance in TRMM rain type classification and latent heating estimation. The radars used in this study have considerably different viewing geometries and resolutions, demanding non-trivial mapping procedures in common earth-relative coordinates. Mapped vertical cross sections and mean profiles of reflectivity from the PR, EDOP, and ground-based radars are compared for six cases. These cases cover a stratiform frontal rainband, convective cells of various sizes and stages, and a hurricane. For precipitating systems that are large relative to the PR footprint size, PR reflectivity profiles compare very well to high-resolution measurements thresholded to the PR minimum reflectivity, and derived variables such as bright band height and rain types are accurate, even at high PR incidence angles. It was found that for, the PR reflectivity of convective cells small relative to the PR footprint is weaker than in reality. Some of these differences can be explained by non-uniform beam filling. For other cases where strong reflectivity gradients occur within a PR footprint, the reflectivity distribution is spread out due to filtering by the PR antenna illumination pattern. In these cases, rain type classification may err and be biased towards the stratiform type, and the average reflectivity tends to be underestimated. The limited sensitivity of the PR implies that the upper regions of precipitation systems remain undetected and that the PR storm top height estimate is unreliable, usually underestimating the actual storm top height. This applies to all cases but the discrepancy is larger for smaller cells where limited sensitivity is compounded by incomplete beam filling. Users of level three TRMM PR products should be aware of this scale dependency.

Contents: General Aspects of High Resolution Radar, High Resolution Radar Systems and Their Operational Environment, Special Components for use in High Resolution Radar, Motion Compensation for SAR, Detection and Imaging of Moving, and Signal and Data Processing. Compilation Report, NATO furnished.

This report addresses a problem of estimation of a constant false alarm rate (CFAR) processing loss for a high-resolution maritime radar system on an example of a generic radar system Anti-Submarine Warfare mode and discusses approaches to modelling of the detection performance for such a system. It has been shown that the value of the CFAR loss for a high-resolution radar system can vary considerably over a radar detection range, dependent on the clutter scenario and the CFAR detection processing used and, therefore, can not be given by a single number for the whole detection area, as it is usually done for a low-resolution radar system.

In this period of performance, we finalized the concept for the final demonstration. We have also demonstrated bench top frequency synchronization through our RF frontend.

A ten-nanosecond-pulse, rapid-scan, X-band radar was designed, built, and installed aboard the USS MALOY (EDE 791). The capability of this radar for submarine periscope detection was investigated. It was found that the high range resolution and rapid-scan features permitted resolution of individual waves and showed their growth, movement, and decay. Periscope detection and tracking capability were found to be superior to that of conventional search radars because of the ability to distinguish periscope radar return from that of the sea background. However, antenna configuration and low average power in the experimental radar limited tracking range to about 6000 yd. (Author)

High resolution radar data for the lunar surface were acquired over 14 sites in June and November 1990 using the new 10 MHz data taking system at the Arecibo Observatory. The raw data collected for each site covers an area approximately 100 by 400 km and will be processed using delay-Doppler techniques into images of backscatter cross section with three fo four independent looks. All observations transmitted a circularly polarized signal and both senses of circular polarization were received containing the polarized and depolarized component of the backscatter signal. The relative power in these two polarizations provides useful information on properties of the surface, in particular surface roughness. The effort to date focused on the initial data analysis with new software written to perform a full synthetic aperture focusing on the raw radar data. This analysis will involve the use of complementary high resolution optical and topographic data sets to aid interpretation of surface scattering mechanisms.

In this performance period we performed the first measurements with the digital synchronization transceiver hardware. We have characterized the tenability and stability of the reference clocks used to clock the transceiver's digital hardware. We have tested the ADC board, and have discovered several issues with its performance. We have completed the redesign of the ADC board to address these issues. The RF front-end is in manufacture now, and will be tested shortly. We have finalized our approach to frequency synchronization which addresses the effects of multipath and mobility. We have tested the frequency synchronization algorithm in a loopback test on the digital transceiver hardware. We are designing a final demonstration using the synchronization transceiver and in-house radar- and high-precision hardware.

A comparison of single-range cell detection and integrated contiguous range-cell detection for a high-range resolution radar is presented. A simulation was used to generate probability of detection curves for the two detection strategies using ten target models with different target scattering characteristics. The integrated range-cell detection strategy is superior in all cases except when the target is composed of a single strong flare point. (Author)

During this period of performance, we processed data collected in different node location configurations for accuracy of the currently implemented algorithm, which is an edge detection algorithm. It sets the base line performance of the current ranging system. In the next reporting periods, we will reprocess this data to show the improvement achievable by digital beam forming. Figure 1 shows the correlation between the actual measured range between the master and the slave and the reported range (One-Time Of Flight, or OTOF) from our system. Our data shows an RMS range error of 2.6 meters for the outdoor case. We also processed data collected in two indoor configurations: LOS and non-LOS. The correlation between the actual range and reported OTOF for these two subsets are shown separately in Figure 2. This plot shows that for the non-LOS case, the range has an RMS error of 11.7 meters. A second set of data was taken inside the Intelligent Automation building (shown in Figure 3) at similar waypoints. This plot indicates that the system is quite repeatable even for the non-LOS case when the experiment location is the same. Currently we are investigating algorithms to improve the range accuracy of our system. The two algorithms that we are studying are channel estimation and digital beam forming. In addition to recording the reported OTOF during our previous indoor/outdoor experiments, we have recorded the I and the Q data reported by our system. This data will be used to study these algorithms for bistatic radar imaging and range accuracy improvement

This article is from Sensors (Basel, Switzerland) , volume 12 . Abstract 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.

This article is from Sensors (Basel, Switzerland) , volume 12 . Abstract 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.

This article is from Sensors (Basel, Switzerland) , volume 12 . Abstract 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.

We consider the application of a spotlight-mode synthetic aperture radar (SAR) imaging technique to the problem of high-resolution imaging. This approach offers improved image quality, compared with conventional processing, at the expense of slightly increased computational effort.

During the evolvement of autonomous driving technology, obtaining reliable 3-D environmental information is an indispensable task in approaching safe driving. The operational behavior of automotive radars can be precisely evaluated in a virtual test environment by modeling its surrounding, specifically vulnerable road users (VRUs). Such a realistic model can be generated based on the radar cross section (RCS) and Doppler signatures of a VRU. Therefore, this work proposes a high-resolution RCS measurement technique to determine the relevant scattering points of different VRUs.

The research supported by the grant: (a) develops the Cramer-Rao lower bound (CRLB) of the target localization estimation error for the general case of MIMO radar with multiple waveforms with non-coherent and coherent observations; (b) finds a closed-form solution for the best linear unbiased estimator (BLUE) of target localization for coherent and non-coherent MIMO radars, providing a closed-form solution and a comprehensive evaluation of the performance of the estimator's MSE. This gives insight into the relation between sensor locations, target location, and localization accuracy through the use of the geometric dilution of precision (GDOP) metric; (c) present an analysis on the ambiguity arising in the high resolution localization due to sidelobe characteristics of the MIMO system using the Ziv-Zakai Bound (ZZB). (d) leveraging the concept of compressed sensing, it shows that by properly choosing a sufficient number of random sensors the ambiguities can be made arbitrarily small. Furthermore, the number of sensors can be trade with computational complexity, demonstrating that high resolution can be obtained with a relatively low number of randomly placed sensors

This report details progress in the FY10 period of performance on development, implementation and testing of hardware and algorithms for highly accurate wireless synchronization. FY10 work has largely focused on 1) redesigning the hardware to achieve higher synchronization resolution and accuracy, increase the operational distance between synchronization transceivers, and increase robustness to interference, and 2) Complete Matlab simulations of the entire synchronization algorithm, for cases where the synchronization transceivers are moving, and significant multipath reflections are present in the channel.

During the past decade, direct measurements of ocean turbulent friction velocity and current velocity profiles have been conducted in polar regions using Autonomous Ocean Flux Buoys (AOFBs). Recent use of Synthetic Aperture Radar (SAR) imagery augmented by digital image processing techniques has proven to be an effective means of monitoring ice conditions. This study examines the relationship between ice-ocean drag coefficients and SAR-derived open water area, feature perimeter and ice ridge length. Drag coefficients are calculated from AOFB current speed and friction velocity measurements collected between 5 October and 29 October 2018 in the Beaufort Sea. Threshold and image processing techniques were applied to a total of 82 SAR images at 6 logarithmically spaced radial upstream distances from the AOFB to classify the three ice feature types. The results indicate that sparse statistics associated with the size and image processing limitations within the near field of the AOFB, coupled with a lack of high resolution satellite imagery, stifled the SAR’s ability to accurately characterize the relationship between ice-ocean drag coefficients and ice feature density distributions within upstream radial sectors within the buoy-centered 20 x 20 km SAR images.

A third-order co-occurrence texture analysis technique was applied to samples of synthetic aperture radar imagery. This technique was applied to four classes of terrain features on selected samples of radar imagery. The four classes considered were forests, cities, agricultural fields, and water. A fracture vector was computed from samples of each class. A linear feature selection technique was applied for dimensionality reduction, and a pseudo-inverse classifier was developed. This classifier was applied to the original training samples as well as to other samples from the same imagery. Keywords include: Texture analysis; Pattern recognition; and Radar imagery.

This report describes the design of a hand-held, portable, microprocessor- controlled, high-resolution radar (HRPR). This report, however, does not include the design of the transmitting and receiving antennas. The high-resolution radar system is designed to be portable, hand held, and microprocessor controlled. The generated carrier is an exponentially decaying sinusoidal wave with a frequency in the GHz range. In this high- resolution radar, analog-to-digital conversion is performed through an integrated circuit chip at a rate of multiple giga samples per second. In addition, digital signal processing is performed and an inversion scheme is embedded in memory chips to generate electromagnetic profiles in real time. In order to achieve high-range resolution, digital codes of certain length such as Barker, Welti, or Frank codes can easily be implemented in this radar system through the application of complementary metal oxide semiconductor (CMOS) logic. The coding of the carrier is made possible through the application of a digitally controlled phase shifter. Power consumption of this high-resolution radar is moderate. Thus, in addition to being hand held, the complete system is mountable on any vehicle as well. As a result, this radar system can be used to perform target and media identification in real time. This process is totally performed by the micro- processor of the system and identification results are displayed visually. The portable high-resolution radar consists of four parts: a transmitter, a receiver, a microprocessor, and d-c power supply.

This Phase I SBIR Final Report addresses the development of a novel rapid scanning radar interferometer designed to map the surface topography of the ocean surface within several hundred meters of an unmanned surface vehicle (USV). A system capable of mapping local sea conditions can help stabilize a USV in high seas by providing input data to an adaptive vessel control system. The proposed interferometer will operate in much the same way as conventional marine radar, enclosing a rotating pair of fan beam antennas in a radome near the top of the USV to provide 360-degree coverage. The system described in this report is based on proven radar interferometry technology developed for oceanographic research applications. As part of this contract we developed a software simulation of the mapping process, accounting for realistic sea states and expected radar parameters. Based on the results of these simulations we designed a prototype system, including the radar, data system, and auxiliary sensors and interfaces necessary to implement real-time stabilization of a USV.

This report presents trade-off studies on Time-Frequency Distribution (TFD) algorithms and a methodology for fusing them to achieve better target characterization. It is shown that TFD algorithmic fusion considerably increases the detectability of signals while suppressing artifacts and noise. The report reviews a sample of representative TFD algorithms. Their performance is studied from a qualitative and quantitative point of view. For simplicity, we considered the mean-squared error as a measure of performance in the quantitative trade-off studies. The TFD algorithmic fusion is performed using a self-adaptive signal. It may be adjusted to work for a wide range of signal-to-noise ratios. The algorithm uses the first two terms of the Volterra series expansion and we treat the outputs of the time-frequency algorithms as the variables of a Volterra series and the coefficients of the series are estimated through training sets with a least-squares algorithm. Simplistic TFD algorithmic fusion methods (e.g., weighted averaging or weighted multiplication) are special cases of the proposed fusion technique. We demonstrate the effectiveness of TFD algorithmic fusion method using experimental High Range Resolution (HRR) radar data and simulated data.

By combing the ultra-fast ( 100 GHz) near-ballistic uni-traveling carrier photodiode (NBUTC-PD) and advanced optical pulse shaper system, we demonstrate the photonic generation and detection of (near) real-time arbitrary waveform at W-band with ultra-high time-bandwidth product. By use of such setup, remote-ranging (5 meters) at Wband with fine resolution ( 5 mm), has also been successfully achieved.

By combing the ultra-fast ( 100 GHz) near-ballistic uni-traveling carrier photodiode (NBUTC-PD) and advanced optical pulse shaper system, we demonstrate the photonic generation and detection of (near) real-time arbitrary waveform at W-band with ultra-high time-bandwidth product. By use of such setup, remote-ranging (5 meters) at Wband with fine resolution ( 5 mm), has also been successfully achieved.

This is a theoretical study examining the possibility to use a commercial, shipborne navigational radar, for target classification and identification, without changing its electronic signature. The reason for such a modification is that using sophisticated pulse forms for target recognition can betray the user's presence and give an intelligence advantage to potential enemy platforms. In order to extract a target's class or identity the data of the radar's video detector are fed to a high performance PC with digitizing capability. There the target's class is obtained through a series of transforms, while the target's identity is obtained by computing he target's frequency response to a very short pulse. Through the MUSIC method. While the classification process does not require any changes in the transmitter, in order to obtain target identification in tactically useful ranges it is necessary to increase the transmitter's power and add an additional very short pulse.

The overall objective of our polarimetric research is to conduct a unified and cohesive investigation to answer the question: How can polarization properties of targets/background speckle be utilized either by themselves or in concert with other electromagnetic probing methods such as doppler, multispectral, pulse compression, etc., to best provide a basis for radar target classification, imaging, and identification? Scattering objects of interest include airborne/ground/marine targets of a large variety of sizes, shapes, and material decomposition and embedded in varied stationary/moving/fluctuating background scatter, which, we are confident, can most effectively be characterized via polarimetric radar/scatterometer methods including both coherent and partially coherent wave treatments. It is specific objective of this task to approach and to investigate the polarimetric radar clutter problem using a unique approach of a strongly interdigitalizing analytical, modeling, computer-numerical/graphical, and measurement interpretive nature. A basic theory for a model-independent clutter description which can be applied to any specific type of clutter without a priori knowledge of the clutter model, i.e., a model-independent clutter description, in theory, is introduced.

In this paper, we consider compressive sensing (CS)-based recovery of delays and Doppler frequencies of targets in high resolution radars. We propose a novel sub-Nyquist sampling method in the Fourier domain based on difference sets (DS), called DS-sampling, to create dictionaries with highly incoherent atoms. The coherence of the dictionary reaches the Welch minimum bound if the DS-sampling is employed. This property let us to implement sub-Nyquist high resolution radars with minimum number of samples. We also develop a low complexity recovery method, based on structured CS and propose a new waveform, called difference set--frequency coded modulated (DS-FCM) waveform, to boost the recovery performance of the sub-Nyquist radar in noisy environments. The proposed method solves some of the common problems in many CS-based radars and overcome disadvantages of the conventional Nyquist processing, i.e. matched filtering in high resolution radar systems. The proposed method allows us to design sub-Nyquist radars, which require less than 2% of Nyquist samples and recover targets without resolution degradation in comparison to the conventional Nyquist processing.

This report describes an over-the-horizon radar with a high-resolution imaging capability using time reversal. By incorporating the extended virtual aperture concept enabled by multipath interference into a double-pass conjugate image scanning scheme, high-resolution radar imaging can be achieved without requiring extensive computation or a priori knowledge of environmental conditions. Initial proof-of-concept experimental results on several key features of time reversal, such as reciprocity, temporal focusing, spatial focusing, multipath-enabled extended virtual aperture, and polarization diversity time reversal, are demonstrated at HF or VHF.

NAS 1.26:3269 Digitized from IA1177305-08-0057 , IA1177305-08-0058 .

This is the final report on a two-year contract entitled 'Measurement of Sea Scatter and Buoy Tracks at Long Ranges by High-Resolution OTH-B Radar.' The Wide Aperture Research Facility (WARF), a high-resolution skywave high- frequency (HF) radar located in central California, was used to obtain remote measurements of the ocean wave spectrum, overwater wind velocity, and ocean currents in the North Pacific Ocean. The ocean currents were determined by tracking drogued and undrogued drifting buoys carrying a low-power HF repeater. Three types of sea backscatter Doppler spectra were recorded to determine the ocean wave spectrum and the wind velocity: (1) Backscatter from wide areas of the ocean to develop techniques for mapping wind fields, (2) Backscatter from limited areas near research vessels, Navy ships, and ships of opportunity to correlate the observed and radar-measured wind field; (3) Long-term coherent samples of backscatter for high-resolution off-line processing to derive the ocean wave spectrum.

This thesis is a reference for the Advanced Application Flight Experiment (AAFE) altimeter. The transmitter and receiver subsections are described and measurements of their current state is provided. During the 1994 NASA Greenland Experiment, the altimeter experienced several hardware malfunctions. The process of returning the radar to its fully operational state is presented in detail and necessary design modifications are explained. An updated radar user's manual is included along with various circuit designs which need to be implemented. The thesis is intended to provide an incoming graduate student with a solid foundation of the fundamentals of AAFE altimeter operation.

The objective of this project is to develop a joint high dynamic range photography and high range resolution RADAR system on mobile platforms to provide predischarge threat warning in urban and mountain environments. This program expands upon the sensor and processing concepts of MTRI Counter RPG and Counter Sniper programs.

This thesis examines the discrimination of targets with Ultra High Range Resolution (UHRR) radar data. Using these measured signals from frontal aspect angles of four aircraft classes, the baseline performance of the Adaptive Gaussian Classifier (AGC) is tested with respect to aligning exemplars to templates. Alignment plays a crucial role in the AGC's classification performance which can degrade by 11% for a target class. The AGC is compared to non-parametric classifiers, but no statistically significant degradation of performance is found. Data separability is analyzed by hounding the Bayes error. The data is well separated in a statistical sense. A feature selection algorithm based on analysis of the decision boundary, is applied to find a reduced feature set, which are linear combinations of the original features. These features are optimized with respect to classification error rather than reconstruction error. This technique is extended to deduce the relevant features in the original feature space. Fewer than 5% of the features in the original feature space may be used to attain an improved classification rate. This new method is a true reduction of features and shows improvement up to 15%. Discrimination of UHRR radar signatures using a multiresolution analysis is proposed. The decision boundary analysis chooses relevant wavelet scales with respect to classification. Some improved performance against an entropy based measure is observed for limited feature sets. The technique developed here successfully chooses the scale that causes classification performance to peak within 5% of the performance in the full-dimensional or reduced-dimensional UHRR radar signature space.

The system is composed of an optical cavity with a laser and a mode locking means to build up an optical pulse. An optical switch is also provided within the cavity to convert the polarization of the optical pulse generated within the cavity. The optical switch comprises an electro-optical crystal driven by a time delayed driver circuit which is triggered by a coincident signal made from an optical pulse signal and a gating pulse signal. The converted optical pulse strikes a polarization sensitive prism and is deflected out of the cavity toward the pending target in the form of a pulse containing most of the optical energy generated by the laser in the pulse build-up period. After striking the target, the reflected energy is picked up by a transceiver with the total travel time of the pulse being recorded.

The system is composed of an optical cavity with a laser and a mode locking means to build up an optical pulse. An optical switch is also provided within the cavity to convert the polarization of the optical pulse generated within the cavity. The optical switch comprises an electro-optical crystal driven by a time delayed driver circuit which is triggered by a coincident signal made from an optical pulse signal and a gating pulse signal. The converted optical pulse strikes a polarization sensitive prism and is deflected out of the cavity toward the pending target in the form of a pulse containing most of the optical energy generated by the laser in the pulse build-up period. After striking the target, the reflected energy is picked up by a transceiver with the total travel time of the pulse being recorded.

The goal of this project is to formulate and investigate new approaches for forming images of radar targets from spotlight-mode, delay- doppler measurements. These measurements could be acquired with a high- resolution radar-imaging system operating with an optical-or radio-frequency carrier. Two approaches are under study. The first is motivated by an image- reconstruction algorithm used in radionuclide imaging called the confidence- weighted algorithm; here, we will refer to this approach as the chirp-rate modulation approach. The second approach is based on more fundamental principles which starts with a mathematical model that accurately describes the physics of an imaging radar-system and then uses statistical-estimation theory with this model to derive processing algorithms; we will refer to this as the estimation- theory approach. Progress during this reporting period has been made on: (1) extending the estimation-theory approach to include a constraint on input signal-to-noise ratio; (2) extending the estimation-theory approach to include a sieve constraint for stabilizing image estimates, (3) extending the estimation- theory approach to include a specular or glint component in the radar-echo data; (4) analyzing the performance of the estimation-theory approach through computer simulations; and (5) modifying the chirp-rate modulation approach through the introduction of the Wigner-Ville distribution. A patent was awarded associated with the chirp-rate modulation approach. A copy of the patent is bound into this report.

A three-dimensional imaging radar operating at high frequency e.g., 670 GHz radar using low phase-noise synthesizers and a fast chirper to generate a frequency-modulated continuous-wave (FMCW) waveform, is disclosed that operates with a multiplexed beam to obtain range information simultaneously on multiple pixels of a target. A source transmit beam may be divided by a hybrid coupler into multiple transmit beams multiplexed together and directed to be reflected off a target and return as a single receive beam which is demultiplexed and processed to reveal range information of separate pixels of the target associated with each transmit beam simultaneously. The multiple transmit beams may be developed with appropriate optics to be temporally and spatially differentiated before being directed to the target. Temporal differentiation corresponds to a different intermediate frequencies separating the range information of the multiple pixels. Collinear transmit beams having differentiated polarizations may also be implemented.