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  • Inorganic Chemistry  (768)
  • COMMUNICATIONS
  • 1970-1974  (998)
  • 1973  (998)
Collection
Keywords
Publisher
Years
  • 1970-1974  (998)
Year
  • 1
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    A spaceborne receiver for measuring electromagnetic field intensity (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-08-13
    Description: Description of a very accurately controlled receiver for monitoring the electromagnetic radiations in both existing and projected space communication bands. Based on analysis of the existing and projected space communication bands, 108 to 174 MHz, 240 to 478 MHz, and 1535 to 1665 MHz were covered. The receiver achieves accurate control via a digitally tuned synthesizer and a wide range of digital control including frequency band coverage and gain control selection. Digital memory was provided to store 16 separate digital command instructions which can be programmed via a command data link. The receiver provides for transmission to the ground of both a predetection signal and signals in digital format, which in turn, were provided by sampling and analog-to-digital conversions.
    Keywords: COMMUNICATIONS
    Type: International Telemetering Conference; Oct 09, 1973 - Oct 11, 1973; Washington, DC
    Format: text
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
  • 2
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    Balloon-aircraft ranging, data, and voice experiment. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-08-13
    Description: The test facilities used in the experiment consisted of a ground station, a balloon platform, radar tracking stations, and a test aircraft. As a direct result of the experiment, several modifications have been incorporated into the equipment. The two most important modifications were the introduction of a 10-sec delay into the search mode and the use of differentially coded phase shift keying for the data channel.
    Keywords: COMMUNICATIONS
    Type: International Conference on Satellite systems for mobile communications and surveillance; Mar 13, 1973 - Mar 15, 1973; London
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Transmission of radiometer data from the Synchronous Meteorological Satellite (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Synchronous Meteorological Satellite uses a spin scanner radiometer which generates eight visual signals and two infrared signals. These signals are multiplexed and converted into a 28-Mbps data stream. This signal is transmitted to ground by quadriphase modulation at 1686.1 MHz. On the ground, the digital signal is reconstructed to an analog signal. To conserve bandwidth, an analog-to-digital converter with a nonlinear transfer function was used for the visual signals. The size of the quantization step was made proportional to the noise output of the scanner photomultiplier tube which increases as the square root of incident light. The radiometer data transmission link was simulated on a digital computer to determine the transfer function. Some results of the simulation are shown.
    Keywords: COMMUNICATIONS
    Type: International Telemetering Conference; Oct 09, 1973 - Oct 11, 1973; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    A review of multiple amplitude-phase digital signals (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper reviews the data rate, error rate, and signal-to-noise ratio relationship for various uncoded M-ary digital amplitude modulation (AM), phase modulation (PM), and combined AM-PM systems. These signal systems have the common virtue that expanding the number of possible signals to be transmitted increases the data rate but not the bandwidth. A general treatment of the error rate of M-ary digital AM-PM permits development of a simple yet accurate expression which approximates the increase in average signal-to-noise ratio (over that of binary phase shift keying) required for constant error performance. This equation provides insight into why arrays differ in their signal-to-noise ratio requirements.
    Keywords: COMMUNICATIONS
    Type: International Telemetering Conference; Oct 09, 1973 - Oct 11, 1973; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    RFI analysis applied to the TDRSS system (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The effect of radio frequency interference (RFI) on the proposed Tracking and Data Relay Satellite System (TDRSS) was assessed. The method of assessing RFI was to create a discrete emitter listing containing all the required parameters of transmitters in the applicable VHF and UHF frequency bands. The transmitter and spacecraft receiver characteristics were used to calculate the RFI contribution due to each emitter. The individual contributions were summed to obtain the total impact in the operational bandwidth. Using an as yet incomplete emitter base, it is concluded that the 136- to 137-MHz band should be used by TDRSS rather than the whole 136- to 138-MHz band because of the higher interference levels in the 137- to 138 MHz band. Even when restricting the link to 136 to 137 MHz, the existing link design is marginal, and it is recommended that interference reduction units, such as the adaptive digital filter, be incorporated in the TDRSS ground station.
    Keywords: COMMUNICATIONS
    Type: International Telemetering Conference; Oct 09, 1973 - Oct 11, 1973; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Measuring terrestrial radio frequency interference at orbit altitudes (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An experiment has been designed to measure and characterize the effect of man-made interference on satellite receivers at orbital altitudes. The experiment, as designed, requires dedicated hardware on a spacecraft of specified orbit and will measure (within the frequency range from 400 MHz to 12.4 GHz) peak levels of interference in cells dimensioned in space, time, and frequency. The experiment will provide data indicative of some of the statistical characteristics of interference levels at satellite orbital altitudes and will provide designers of satellite communications links with new facilities for the prediction and prevention of interference problems.
    Keywords: COMMUNICATIONS
    Type: International Telemetering Conference; Oct 09, 1973 - Oct 11, 1973; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    The ATS-F radio frequency interference measurement experiment (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The technical objectives of the uplink interference tests and measurements to be performed during this experiment are set forth as the determination of the integrated interference power from all 6-GHz terrestrial sources sharing the common carrier band with the RF field of view of the ATS-F satellite; the establishment of practical limits of receiver antenna gain-to-noise temperature ratios for satellites sharing the common 6-GHz carrier band; and the determination of the geographical and frequency distribution of 6-GHz terrestrial sources sharing the common carrier band. A brief description of the RF interference measurement system with some details on its hardware and subsystems is included. The performance characteristics of the mission and a measurement program are discussed.
    Keywords: COMMUNICATIONS
    Type: International Telemetering Conference; Oct 09, 1973 - Oct 11, 1973; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Radar studies of arctic ice and development of a real-time Arctic ice type identification system (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Studies were conducted to develop a real-time Arctic ice type identification system. Data obtained by NASA Mission 126, conducted at Pt. Barrow, Alaska (Site 93) in April 1970 was analyzed in detail to more clearly define the major mechanisms at work affecting the radar energy illuminating a terrain cell of sea ice. General techniques for reduction of the scatterometer data to a form suitable for application of ice type decision criteria were investigated, and the electronic circuit requirements for implementation of these techniques were determined. Also, consideration of circuit requirements are extended to include the electronics necessary for analog programming of ice type decision algorithms. After completing the basic circuit designs a laboratory model was constructed and a preliminary evaluation performed. Several system modifications for improved performance are suggested. (Modified author abstract)
    Keywords: COMMUNICATIONS
    Type: NASA-CR-138694 , AD-775249 , RSC-835-6
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Advanced tracking and data relay experiments study: Multimode transponder experiment equipment (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Plans and implementation concepts were developed for a series of experiments utilizing a Multimode Transponder mounted in an aircraft working either through a spacecraft or directly with a ground station which would simulate a TDRSS user working through the TDRSS. The purpose of the experiments is to determine the best modulation and encoding techniques for combating RFI in discreet bands. The experiments also determine the feasibility and accuracy of range and range rate measurements with the various modulation and encoding techniques. An analysis of the Multimode Transponder and ground support equipment is presented, and the additional equipment required to perform the experiments described above is determined.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-132930 , R-4741
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Advanced tracking and data relay experiments study: Multimode transponder experiment analysis procedure (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Plans and implementation concepts were developed for utilizing a multimode transponder mounted in an aircraft working either through a spacecraft or directly with a ground station. The purpose would be to determine the best modulation and encoding techniques for combating RFI and multipath propagation and to determine the characteristics of VHF and UHF RFI in discreet bands. The experiments would also determine the feasibility and accuracy of range and range rate measurements with the various modulation and encoding techniques.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-132913 , R-4742
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
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