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  • 1
    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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  • 2
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: Image data are compressed for transmission by simple, economical circuitry. Compressor handles data in blocks of 64 samples. Mean from previous line is subtracted, and pseudo-random sequence of positive and negative 1's multiplies samples of each block. Hadamard transform applied to blocks yields 64 transform coefficients. Each coefficient is compared with approximation to corresponding coefficient of previous line, and difference is quantized. Values are transmitted or stored. Procedure is reversed to reproduce image.
    Keywords: ELECTRONIC SYSTEMS
    Type: NPO-14041 , NASA Tech Briefs (ISSN 0145-319X); 3; 1; P. 28
    Format: text
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  • 3
    Publication Date: 2019-06-27
    Description: The application of modern LSI technology to the development of a time-domain azimuth correlator for SAR processing is discussed. General design requirements for azimuth correlators for missions such as SEASAT-A, Venus orbital imaging radar (VOIR), and shuttle imaging radar (SIR) are summarized. Several azimuth correlator architectures that are suitable for implementation using custom LSI devices are described. Technical factors pertaining to selection of appropriate LSI technologies are discussed, and the maturity of alternative technologies for spacecraft applications are reported in the context of expected space mission launch dates. The preliminary design of a custom LSI time-domain azimuth correlator device (ACD) being developed for use in future SAR processors is detailed.
    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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  • 4
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    Publication Date: 2019-06-28
    Description: Azimuth correlator circuit synthetic-aperature radar (SAR) is designed for single integrated circuit (IC) chip. Azimuth correlator modules constructed with sets of such chips could make real-time signal processing possible. Primary advantages are realized in areas of weight and power requirement reductions.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: NPO-14614 , NASA Tech Briefs (ISSN 0145-319X); 4; 4; P. 468
    Format: text
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  • 5
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    Publication Date: 2019-07-13
    Description: The paper discusses an SAR problem based on actual requirements set forth by NASA for a spaceborne application. The requirements for high resolution and high quality necessitate a data sampling rate of 7.5 MHz. For each data value 1,025 4-bit complex multiply + add operations are needed, which is equivalent to 7.7 GHz complex multiply + add operation rate. Since this rate is much too high for general purpose systems, a special-purpose device was sought. This paper discusses two architectures based on parallel operation of 1,025 identical cells, each of which is capable of performing arithmetic, storage, and several control operations. The operation rate in each device is only 7.5 MHz, which is quite manageable, especially with the help of a substantial degree of pipelining. A computational-mathematical analysis is used as a primary tool for evaluating the design and some of its tradeoffs. Two different approaches are discussed and compared; both are based on having 1,025 identical cells working in parallel, but differ in their dual approaches to the flow of data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Digital processing of aerial images; May 22, 1979 - May 24, 1979; Huntsville, AL
    Format: text
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  • 6
    Publication Date: 2019-07-13
    Description: The application of modern LSI technology to the development of a time-domain azimuth correlator for SAR processing is discussed. General design requirements for azimuth correlators for such missions as Seasat-A, Venus Orbital Imaging Radar, and Shuttle Imaging Radar are summarized. Several azimuth correlator architectures suitable for implementation using custom LSI devices are described. Technical factors pertaining to selection of appropriate LSI technologies are discussed, and the maturity of alternative technologies for spacecraft application is examined in the context of the expected launch dates. In particular, it is demonstrated that a custom LSI device is practical for a system as complex as the DMSP.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Synthetic Aperture Radar Technology Conference; Mar 08, 1978 - Mar 10, 1978; Las Cruces, NM
    Format: text
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  • 7
    Publication Date: 2019-07-13
    Description: This paper presents the results obtained in a continuing investigation of real-time distributed processing systems which is being conducted at the Jet Propulsion Laboratory. A distributed processor architecture has been developed for control and data handling on a planetary spacecraft. This system, designated the Unified Data System, has been implemented in a feasibility breadboard. The following aspects of the Unified Data System are described: (1) standardized building block elements and their configuration into microprocessor modules, (2) a highly redundant bus structure which connects the various modules and facilitates intercommunications with minimal software support, (3) the structure of software within the individual modules and its coordination between modules, and (4) the mechanisms by which fault-tolerance can be implemented within the network. Through the attributes of multilevel standardization, simplicity, and flexibility, this system is expected to result in significant cost savings to future spacecraft missions.
    Keywords: SPACECRAFT INSTRUMENTATION
    Type: NAECON ''76; National Aerospace and Electronics Conference; May 18, 1976 - May 20, 1976; Dayton, OH
    Format: text
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