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  • 1
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    Performance evaluation of the JPL interim digital SAR processor (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The performance of the Interim Digital SAR Processor (IDP) was evaluated. The IDP processor was originally developed for experimental processing of digital SEASAT SAR data. One phase of the system upgrade which features parallel processing in three peripheral array processors, automated estimation for Doppler parameters, and unsupervised image pixel location determination and registration was executed. The method to compensate for the target range curvature effect was improved. A four point interpolation scheme is implemented to replace the nearest neighbor scheme used in the original IDP. The processor still maintains its fast throughput speed. The current performance and capability of the processing modes now available on the IDP system are updated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Spaceborne Imaging Radar Symp.; p 93-95
    Format: text
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  • 2
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    V-band pseudomorphic HEMT MMIC phased array components for space communications (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Recent advances in pseudomorphic high-electron-mobility transistor (PMHEMT) monolithic microwave integrated circuit (MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. The development of V-band PMHEMT/MMIC components including power amplifiers and phase shifters is described. For the single-stage MMIC power amplifier employing a 200 micron PMHEMT, we achieved 151.4 mW output power (757.0 mW/mm) with 1.8 dB associated gain and 26.4 percent power-added efficiency at 60 GHz. A two-stage MMIC amplifier utilizing the same devices demonstrated small-signal gain as high as 15 dB at 58 GHz. And, for the phase shifter, a four-bit phase shifter with less than 8 dB insertion loss from 61 to 63 GHz was measured.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Solid State Technology Branch of NASA Lewis Research Center; p 15-20
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Pipelined digital SAR azimuth correlator using hybrid FFT-transversal filter (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A synthetic aperture radar system (SAR) having a range correlator is provided with a hybrid azimuth correlator which utilizes a block-pipe-lined fast Fourier transform (FFT). The correlator has a predetermined FFT transform size with delay elements for delaying SAR range correlated data so as to embed in the Fourier transform operation a corner-turning function as the range correlated SAR data is converted from the time domain to a frequency domain. The azimuth correlator is comprised of a transversal filter to receive the SAR data in the frequency domain, a generator for range migration compensation and azimuth reference functions, and an azimuth reference multiplier for correlation of the SAR data. Following the transversal filter is a block-pipelined inverse FFT used to restore azimuth correlated data in the frequency domain to the time domain for imaging.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NAS 1.71:NPO-15519-1
    Format: application/pdf
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  • 4
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    Real-time multiple-look synthetic aperture radar processor for spacecraft applications (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A spaceborne synthetic aperture radar (SAR) having pipeline multiple-look data processing is described which makes use of excessive azimuth bandwidth in radar echo signals to produce multiple-looking images. Time multiplexed single-look image lines from an azimuth correlator go through an energy analyzer which analyzes the mean energy in each separate look to determine the radar antenna electric boresight for use in generating the correct reference functions for the production of high quality SAR images. The multiplexed single look image lines also go through a registration delay to produce multi-look images.
    Keywords: COMMUNICATIONS AND RADAR
    Format: application/pdf
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  • 5
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    Electronic SAR processors for space missions (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental laboratory processor is being developed as a testbed for design of on-board processors for future space missions. The configuration of the experimental processor is described and technical factors pertaining to the design are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: New Mexico State Univ. Proc. of the 1978 Syn. Aperture Radar Technol. Conf.; 19 p
    Format: application/pdf
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  • 6
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    Optimal sampling and quantization of synthetic aperture radar signals (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Some theoretical and experimental results on optimal sampling and quantization of synthetic aperture radar (SAR) signals are presented. It includes a description of a derived theoretical relationship between the pixel signal to noise ratio of processed SAR images and the number of quantization bits per sampled signal, assuming homogeneous extended targets. With this relationship known, a solution may be realized for the problem of optimal allocation of a fixed data bit-volume (for specified surface area and resolution criterion) between the number of samples and the number of bits per sample. The results indicate that to achieve the best possible image quality for a fixed bit rate and a given resolution criterion, one should quantize individual samples coarsely and thereby maximize the number of multiple looks. The theoretical results are then compared with simulation results obtained by processing aircraft SAR data.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-157339 , JPL-PUB-78-41
    Format: application/pdf
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  • 7
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    A derivation of the statistical characteristics of SAR imagery data (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Basic statistical properties of the speckle effect and the associated spatial correlation of SAR image data are discussed. Statistics of SAR sensed measurement and their relationships to the surface mean power reflectivity are derived. The Rayleigh speckle model is reviewed. Applications of the derived statistics to SAR radiometric measures and image processing are considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: ESA SAR Image Quality; p 71-75
    Format: text
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  • 8
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    Considerations on data compression of synthetic aperture radar images (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper describes some analytical results relative to the effectiveness of applying data compression techniques for efficient transmission of synthetic aperture radar (SAR) signals and images. A Rayleigh target model is assumed in the analysis. It is also assumed that all surface reflectivity information is of interest and needs to be transmitted. Spectral characteristics of radar echo signals and processed images are analyzed. Analytical results generally indicate that due to the lack of high spatial correlation in the Rayleigh distributed radar surface reflectivity, application of data compression to SAR signals and images under the square difference fidelity criterion may be less effective than its application to images obtained using incoherent illumination. On the other hand, if certain random variations in radar images are considered as undesirable, substantial compression ratio may be achieved by removing such variations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Seminar on Advances in image transmission techniques; Aug 24, 1976 - Aug 25, 1976; San Diego, CA
    Format: text
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