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  • 1
    Electronic Resource
    Electronic Resource
    Rocket-borne downconverter system for measuring space plasma turbulence (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1056-1060 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For research into space plasma turbulence, we have developed a number of space-flight instruments for making in situ measurements of plasma wave activity. One of these instruments, the NRL downconverter, is used to measure plasma waves in the 2- to 20-MHz frequency range by downconverting a 100-kHz band of frequencies to the baseband. Input frequency tuning is controlled by an imbedded microcomputer, and can be programmed to scan in any desired frequency pattern. The in-phase and quadrature receiver outputs, each having a 50-kHz bandwidth, are processed externally by digital signal processors (DSP). The receiver achieves 35 dB of sideband rejection using a hybrid quadrature mixer design, which incorporates an analog front end with digital signal processing. This design yields 15 dB of improved sideband rejection over more conventional analog techniques. The microcomputer control, DSP processing, and modular design contribute to the flexibility of the receiver, which has allowed the system to be used on a number of different missions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146045
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  • 2
    Electronic Resource
    Electronic Resource
    Space-flight digital signal processor system for on-board processing of experiment data (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3751-3754 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a digital signal processor (DSP) system to extend the capabilities of a variety of scientific instruments used to make in situ ionospheric plasma measurements from sounding rockets and spacecraft. The DSP system is extremely flexible due to the use of a field programmable gate array, sigma-delta analog-to-digital converters, and a highly integrated single-chip DSP. Using virtually identical circuitry, we have operated DSP systems processing data from low-frequency electric field detectors, Langmuir probes, and several radio-frequency receivers on several sounding rockets and spacecraft with different digital telemetry interfaces. The DSP system provides three major improvements to our instruments: (1) reduced telemetry bandwidth (data) requirements, (2) improved signal-to-noise ratio, and (3) digital antialiasing filtering. We describe our DSP system and show three examples of how we have implemented it with our instruments. Similar systems should be of interest to researchers in many fields of research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147143
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Direction finding measurements of type III bursts in both elevation and azimuth (1976)
    Springer
    Solar physics 46 (1976), S. 475-475 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Direction finding measurements with the plasma wave experiments on the HAWKEYE 1 and IMP-8 satellites are used to find the source locations of type III solar radio bursts in elevation (geocentric solar ecliptic latitude) and azimuth (geocentric solar ecliptic longitude) in a frequency range from 31.1 kHz to 500 kHz. IMP-8 has its spin axis perpendicular to the ecliptic plane, hence by analyzing the spin modulation of the signals the location of the type III burst projected into the ecliptic can be found. HAWKEYE 1 has its spin axis nearly parallel to the ecliptic plane, hence the elevation of the source may also be determined. The trajectory of the electrons generating the burst, projected onto the ecliptic plane, follows an Archimedean spiral. Out of the ecliptic plane the trajectory is at a nearly constant heliographic latitude. The electrons originate from a region near a solar flare. With direction measurements of elevation and azimuth along with the modulation factor it is possible to determine the source size. Typical half angle source sizes range from ∼60° at 500 kHz to ∼40° at 56.2 kHz as viewed from the sun.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149871
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    Paper (German National Licenses)
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