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  • Other Sources  (392)
  • COMMUNICATIONS AND RADAR  (199)
  • SPACECRAFT PROPULSION AND POWER  (193)
  • 1980-1984  (392)
  • 1981  (392)
  • 1
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    In:  CASI
    Publication Date: 2006-02-14
    Description: Prediction methods and related propagation results for the evaluation of Earth-space communication paths operating above 10 GHz are presented. Gaseous attenuation, rain, cloud, fog, sand, and dust attenuation, path diversity, signal fluctuations and low angle fading, depolarization effects, bandwidth coherence, and sky noise are considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Propagation Effects Handbook for Satellite Systems Design; p 195-348
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  • 2
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    In:  CASI
    Publication Date: 2006-02-14
    Description: The description and measurement of the macroscopic and microscopic characteristics of rain and rain systems are discussed. The statistical relationships of these characteristics and their effect on polarization and attenuation are considered. Macroscopic characteristics include the size, distribution, and movements of rain cells, the height of melting layers, and the presence of ice crystals. Microscopic characteristics include the size distribution, density, and oblateness of rain drops and ice crystals. The estimation of a major propagation effect, specific attenuation, is described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Propagation Effects Handbook for Satellite Systems Design; p 5-39
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  • 3
    Publication Date: 2006-01-16
    Description: The hydraulic actuation system of the space shuttle main engine is discussed. The system consists of five electrohydraulic actuators and a single engine filter used to control the five different propellant valves, which in turn control thrust and mixture ratio of the space shuttle main engine. The hydraulic actuation system provides this control with a precision of 98.7 percent or an error in position no greater than 1.3 percent of full scale rotational travel for critical positions.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: the 15th Aerospace Mech. Symp.; p 291-301
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  • 4
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The system components and operation of the space shuttle solid rocket booster (SRB) dewatering set are described. The SRB dewatering set consists of a nozzle plug, control console, remote control unit, power distribution unit, umbilical cable, interconnect cables, and various handling and storage items. The nozzle plug (NP) is a remotely controlled, tethered underwater vehicle that is launched from the retrieval vessel (RV) by a crane, descends down the side of the SRB, and is positioned below the SRB nozzle. A TV camera mounted at the top of the NP central core is used by the control console operator to visually guide the NP during descent and docking. The NP is then driven up and locked into the nozzle. Compressed air is passed through the umbilical from the RV, through the NP and into the SRB motor. The water inside the SRB is expelled causing the SRB to rotate to a near horizontal attitude on the surface of the water.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 279-289
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  • 5
    Publication Date: 2006-01-16
    Description: Zero gravity testing in the KC-135 aircraft of flat fold flexible solar array test specimens sufficiently demonstrated the adequacy of the panel design. The aircraft flight crew provided invaluable assistance and significantly contributed to the design and development of the flexible solar array, and ultimately to the potential success of the solar electric propulsion solar array shuttle flight experiment program.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: The 15th Aerospace Mech. Symp.; p 115-136
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  • 6
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    In:  CASI
    Publication Date: 2006-02-14
    Description: Existing data bases accumulated as the result of experiments to gather propagation data on millimeter wave Earth-space links are described. The satellites used are described and results of the significant experiments conducted in the United States are summarized. The data bases consist primarily of cumulative attenuation statistics, though some depolarization measurements are included. Additional summaries of propagation data are cited.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Its Propagation Effects Handbook for Satellite Systems Design; p 155-194
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  • 7
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    In:  CASI
    Publication Date: 2006-02-14
    Description: The key features of the Rice-Holmberg, Dutton-Dougherty, Global, Lin, and Piecewise Uniform Rain Rate models for estimation of cumulative attenuation statistics on Earth-space millimeter paths are summarized. The models provide either rain rate statistics or attenuation statistics, which can be related by use of the specific attenuation and the effective path length relation. The effective path length is defined. The advantages and disadvantages of each model for specific applications are discussed. The Global model is recommended as the design tool for predicting propagation effects in Earth-space communication systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Propagation Effects Handbook for Satellite Systems Design; p 41-101
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  • 8
    Publication Date: 2006-02-14
    Description: The corresponding between a given propagation phenomenon and system performance is considered. Propagation data are related to system performance parameters, allowing the systems engineer to perform the analyses determining how well requirements are met by a given system design, and enabling the systems engineer to modify that design if necessary. The various ways of specifying performance criteria for different kinds of systems are discussed, and a general procedure for system design is presented and demonstrated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Propagation Effects Handbook for Satellite Systems Design; p 349-404
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  • 9
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    In:  CASI
    Publication Date: 2006-02-14
    Description: Sources of depolarization effects on the propagation paths of orthogonally-polarized information channels are considered. The main sources of depolarization at millimeter wave frequencies are hydrometeor absorption and scattering in the troposphere. Terms are defined. Mathematical formulations for the effects of the propagation medium characteristics and antenna performance on signals in dual polarization Earth-space links are presented. Techniques for modeling rain and ice depolarization are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Propagation Effects Handbook for Satellite Systems Design; p 103-154
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  • 10
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    In:  Other Sources
    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 13 p
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  • 11
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 19 p
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  • 12
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    In:  Other Sources
    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 19 p
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  • 13
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 11 p
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  • 14
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 22 p
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  • 15
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 15 p
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  • 16
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 5 p
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  • 17
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 16 p
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  • 18
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 5 p
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  • 19
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 21 p
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  • 20
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    In:  Other Sources
    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 13 p
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  • 21
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 6 p
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  • 22
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 4 p
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  • 23
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 7 p
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  • 24
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 10 p
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  • 25
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 16 p
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  • 26
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 25 p
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  • 27
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 7 p
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  • 28
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 33 p
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  • 29
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 100 p
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  • 30
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 13 p
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  • 31
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 109 p
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  • 32
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 39 p
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  • 33
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 12 p
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  • 34
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 13 p
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  • 35
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    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 19 p
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  • 36
    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 27 p
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  • 37
    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAFF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 5 p
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  • 38
    Publication Date: 2011-08-19
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JANNAFF Handbook: Rocket Exhaust Plume Technol., Chapter 5; 5 p
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  • 39
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    Publication Date: 2011-08-18
    Description: A mathematical model of Viterbi decoder burst error performance is presented. This model allows for computer generation of Viterbi-like error sequences quickly and inexpensively for applications where large amounts of data are required. The model is corroborated through comparisons with actual software decoder simulations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 187-193
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  • 40
    Publication Date: 2011-08-18
    Description: An efficient computational technique is developed to evaluate the performance of coherent receivers with noisy carrier reference and multiple antennas. The received signal is assumed to be uncoded residual carrier BPSK (binary phase shift keying), with a PLL (phase locked loop) used for extracting the carrier. Explicit relationships between the error probabilities and the various system parameters are given. Specific results are given for the performance gain of combined carrier referencing over baseband only combining when the channel alignment process is ideal. A simple asymptotic expression for the performance gain is determined when the number of antennas used is increased without bound. An example using a Block 3 Deep Space Network PLL illustrates the performance of each arraying structure. The technique used is applicable to the performance evaluation for other receivers having similar decision statistics.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 194-206
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  • 41
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    Publication Date: 2011-08-18
    Description: The DSN VLBI System was established as a network system in 1978. The evolution of the VLBI System from Mark 1-79 to Mark 4-85 is described, and the system functional requirements for Mark 4-85 are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 61-76
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  • 42
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    Publication Date: 2011-08-18
    Description: Modification of the currently operational DSN Command System MK 3-80 consisted of improvement of the uplink carrier frequency tuning capability to satisfy Voyager 2 requirements. Upgrading of Command System monitoring functions in the Network Operations Control Center is discussed. The DSN Command System requirements and functional design are described for the Mark 4 Network.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 53-60
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  • 43
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    Publication Date: 2011-08-18
    Description: The proposed design for the microwave subsystem of Project ORION is presented. Performance characteristics and subsystem capabilities are discussed. Functional requirements and key performance parameters are stated for the subsystem as well as a proposed schedule of events.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 10-17
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  • 44
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    Publication Date: 2011-08-18
    Description: A single frequency communication system is considered consisting of K possibly moving users distributed in space simultaneously communicating with a central station equipped with a computationally adapted array of n = or K antennas. Such a configuration could result if K spacecraft were to be simultaneously tracked by a single DSN complex consisting of an n antennas array. The array employs K sets of n weights to segregate the signals received from the K users. The weights are determined by direct computation based on known position information of the K users. Currently known techniques require (for n = K) about (4/3)K to the 4th power computer operations (multiply and add) to perform such computations. A technique that accomplishes this same goal in 8 K to the 3rd power operations, yielding a reduction by a factor K/6, was developed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 118-127
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  • 45
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    Publication Date: 2011-08-18
    Description: Radiometric microwave noise temperature measurements were used to estimate atmospheric transmission loss. The following lumped element model expression is used for the noise temperature contribution, T double prime = T sub p (1 - 1/L). This relationship is used to estimate the transmission loss L in terms of T double prime and the atmosphere effective physical temperature T sub p. This report evaluates T sub p in terms of assumed distributed loss and temperature models. Simplified expressions are presented for low loss applications. For these applications L was determined directly and accurately without integration or iteration.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 87-96
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  • 46
    Publication Date: 2011-08-18
    Description: When high precision is required for range measurement on Earth space paths, it is necessary to correct as accurately as possible for excess range delays due to the dry air, water vapor, and liquid water content of the atmosphere. Calculations based on representative values of atmospheric parameters are useful for illustrating the order of magnitude of the expected delays. Range delay, time delay, and phase delay are simply and directly related. Doppler frequency variations or noise are proportional to the time rate of change of excess range delay. Tropospheric effects were examined as part of an overall consideration of the capability of precision two way ranging and Doppler systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 71-86
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  • 47
    Publication Date: 2011-08-18
    Description: The extension of the 26 meter antenna to 34 meter diameter decreased the F/D ratio. This F/D change resulted in unacceptable gain losses due to the hyperboloid's lateral deflections. A three direction translating mounting device was added to the hyperboloid. This device was controlled by a microprocessor to minimize the offsets of the phase centers in the cassegrain RF system and also compensated for boresight directions. The use of the radiation program to predict the gain losses from displacements computed by a structural computing program using an analytical model of the 34 meter reflector structure is discussed. Field test results showed accurate predictions for the Y and Z hyperboloid translations. In the X direction, the prediction value was low. However, the computed gain losses vs primary foci offsets by the radiation program were verified by field tests.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Telecommun. and Data Acquisition; p 112-120
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  • 48
    Publication Date: 2011-08-18
    Description: The interim frequency standards test facility tests all frequency standards used in the DSN. It is also the central testing facility for testing all ultrastable hydrogen maser frequency standards. This proposed data acquisition/processing system was designed to support the IFSTF by acquiring and processing the large amounts of data generated there.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Telecommun. and Data Acquisition; p 22-30
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  • 49
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    Publication Date: 2011-08-18
    Description: Methods and instrumentation are being developed to determine the frequency stability of Deep Space Stations. The efforts are presently focused on the verification of the stability of the X-band uplink and other RF and microwave subsystems which contribute to the overall stability of the system. The measurement methodology is presented as well as frequency stability data generated with the development measurement system. The system characteristics are highlighted and the potential areas where improvements could be made are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Telecommun. and Data Acquisition; p 35-42
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  • 50
    Publication Date: 2011-08-18
    Description: The subject interface measurements are described for the Ion Auxiliary Propulsion System (IAPS) flight test of two 8-cm thrusters. The diagnostic devices and the effects to be measured include: 1) quartz crystal microbalances to detect nonvolatile deposition due to thruster operation; 2) warm and cold solar cell monitors for nonvolatile and volatile (mercury) deposition; 3) retarding potential ion collectors to characterize the low energy thruster ionic efflux; and 4) a probe to measure the spacecraft potential and thruster generated electron currents to biased spacecraft surfaces. The diagnostics will also assess space environmental interactions of the spacecraft and thrusters. The diagnostic data will characterize mercury thruster interfaces and provide data useful for future applications.
    Keywords: SPACECRAFT PROPULSION AND POWER
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  • 51
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    Publication Date: 2011-08-18
    Description: Propagation phenomena affect the design of radio frequency (RF) transmission systems. Propagation phenomena limit the suitability of portions of the frequency band for some applications, limit the reliability of RF transmission systems, and provide a means of coupling unwanted signals from one system to another with the potential of producing interference. The possibility of interference is the fundamental limitation to the unrestricted use of the frequency band. Phenomena affecting suitability, reliability, and the potential for interference are considered for frequencies in the 1- to 300-GHz range.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE; vol. 69
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  • 52
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    Publication Date: 2011-08-18
    Description: An introduction to the phase four receiver subsystem to be implemented into the DSN for VLBI applications is presented. The key design areas are discussed along with the design approach. Preliminary evaluation data indicate a feasible, straightforward design may be obtained.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 18-29
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  • 53
    Publication Date: 2011-08-18
    Description: The capacity is derived under both peak and average signal power constraints and without a signal bandwidth constraint. A random telegraph wave type signalling scheme of Kabanov is known to achieve capacity provided enough signalling bandwidth is available. In the absence of received background noise, an optimally coded PPM system is shown to achieve capacity with greatly reduced bandwidth as compared to Kabanov signals.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 51-70
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  • 54
    Publication Date: 2011-08-18
    Description: Baseband combining with and without combined carrier referencing for antenna arrays are compared under two scenarios for the Voyager 2 Uranus encounter. The combined carrier reference scheme is estimated to outperform the baseband only scheme by less than 0.3 dB E (sub b)/N (sub 0) at a bit error probability of 0.005. These results were attained both with mathematical modeling and software Viterbi decoder simulations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Telecommun. and Data Acquisition; p 105-111
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  • 55
    Publication Date: 2011-08-18
    Description: The ground and spacecraft hardware research, design, and implementation lead to an end to end in flight technology demonstration on the International Solar Polar Mission spacecraft. An introduction to the overall effort is given and the flight experiment objectives are established. The expected improvements in the telecommunications performance are summarized. Also presented is a conceptual mission operations plant.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Telecommun. and Data Acquisition; p 50-62
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  • 56
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    Publication Date: 2011-08-18
    Description: Rectenna deviations are described which produce errors in the since of reduced efficiency and/or scattering. Three classes of deviations are emphasized: random construction variations; systematic variations; and atmospheric induced randomness.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 93-107
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  • 57
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    Publication Date: 2011-08-18
    Description: The radiation patterns characteristic of an indefinite planar array of isotropic antennas was investigated. Particular emphasis was given to the grating lobe scatter from the rectenna. It is shown that an idealy arrayed rectenna of indefinite extent would produce grating lobes which are impulsive. It is further shown that a shift to finite extent or introduction of typical variations in element placement should generate more typical patterns.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 81-90
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  • 58
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    Publication Date: 2011-08-18
    Description: A model is presented which quantifies the electromagnetic modes (field configurations) in the immediate vicinity of the rectenna element. Specifically, the waveguide model characterizes the electromagnetic modes generated by planar waves normal to the array. The model applies only to incidence normal to the array.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 59-77
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  • 59
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    Publication Date: 2011-08-18
    Description: The conditions required for a large rectenna array (i.e., reference design) to absorb nearly 100% of transmitted energy were studied. Design parameters including element spacing, and the manner in which these affect scatter were formulated. Amplitudes and directions of scatter and development of strategies for mitigation were also investigated. The effects on rectenna behavior of external factors such as weather and aircraft overflights were determined.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 1-36
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  • 60
    Publication Date: 2011-08-18
    Description: This paper considers the performance of quadrature partial response (QPR) in the presence of jamming. Although a QPR system employs a single sample detector in its receiver, while quadrature amplitude shift keying (or quadrature phase shift keying) requires a matched-filter type of receiver, it is shown that the coherent detection performances of the two in the presence of the intentional jammer have definite similarities.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-29; Nov. 198
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  • 61
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    Publication Date: 2011-08-18
    Description: Some of the useful formulas and methods for determining antenna beam solid angle are presented. The applicability of these formulas in evaluating radiometric systems performance is illustrated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 168-172
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  • 62
    Publication Date: 2011-08-18
    Description: Comparison of four scanning schemes including CONSCAN indicates that CONSCAN with signal cleanup and protection processes has the greatest merit in terms of accuracy, dependability and automatic unattended operation. Specific problem areas, error sources, and corrective measures are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 116-122
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  • 63
    Publication Date: 2011-08-18
    Description: The increasing density of electrical and electronic circuits in Deep Space Station systems for computation, control, and numerous related functions has combined with the extension of system performance requirements calling for higher speed circuitry along with broader bandwidths. This has progressively increased the number of potential sources of radio frequency interference inside the stations. Also, the extension of spectrum usage both in power and frequency as well as the greater density of usage at all frequencies for national and international satellite communications, space research, Earth resource operations and defense, and particularly the huge expansion of airborne electronic warfare and electronic countermeasures operations in the Mojave area have greatly increased the potential number and severity of radio frequency interference incidents. The various facets of this problem and the efforts to eliminate or minimize the impact of interference on Deep Space Network support of deep space flight projects are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Telecommun. and Data Acquisition; p 125-131
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  • 64
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    Publication Date: 2011-08-18
    Description: Four tests are described which are designed to evaluate the magnitude, type, and frequency of occurence of amplitude and phase variations in the solar power satellite power (SPS) beam as seen by the rectenna. Particular attention is given to the degree of deviation in the propagation observed under two conditions unique to the SPS: monochromaticity; and smallness of the effective aperture of individual rectenna element dipoles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 111-118
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  • 65
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    Publication Date: 2011-08-18
    Description: The model of a rectenna based on the current sheet equivalency of a large planar array is described. The model is mathematically characterized by expression for the fraction of the incident plane wave that is reflected from the sheet. The model is conceptually justified for normal incidence by comparing it to the waveguide model in which evanescent modes, present as beyond and cutoff, correspond to the near field components which become negligible at any significant distance from the antenna array.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 47-56
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  • 66
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    Publication Date: 2011-08-18
    Description: The characteristic of plane waves are derived from Maxwell's equations. The derivation utilizes both the transmission and reflection of plane waves as a basis for its formulation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: A Theoret. Study of Microwave Beam Absorption by a Rectenna; p 39-43
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  • 67
    Publication Date: 2011-08-18
    Description: A functional description of the new eight level ASCII Teletype Subsystem and its constitutent Teletype Assemblies is given. An overview of the implementation of the Teletype Subsystem is presented together with a discussion of the distinct capabilities of its equipment.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition; p 95-102
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  • 68
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    Publication Date: 2011-08-18
    Description: An automatic test was developed to test the ability of the deep space station (DSS) command subsystem and exciter to generate and radiate, from the exciter, the correct idle bit sequence for a given flight project or to store and radiate received command data elements and files without alteration. This test, called the command system output bit verification test, is an extension of the command system performance test (SPT) and can be selected as an SPT option. The test compares the bit stream radiated from the DSS exciter with reference sequences generated by the SPT software program. The command subsystem and exciter are verified when the bit stream and reference sequences are identical. It is a key element of the acceptance testing conducted on the command processor assembly (CPA) operational program (DMC-0584-OP-G) prior to its transfer from development to operations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition; p 112-114
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  • 69
    Publication Date: 2011-08-18
    Description: Historical data on selected communication parameters are presented in tables and charts for 14 deep space missions. Some observations are made about trends in communication capability.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition; p 7-16
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  • 70
    Publication Date: 2011-08-18
    Description: A charge-exchange plasma, generated by an ion thruster, is capable of flowing upstream from the ion thruster and therefore represents a source of contamination to a spacecraft. An analytical model of the charge-exchange plasma density around a spacecraft was used to estimate the contamination which various spacecraft materials may be exposed to. Measurements of plasma density around an ion thruster were compared to this model. Results of experimental studied regarding the effects on various spacecraft materials' properties due to exposure to expected mercury contamination levels are presented.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 231-241
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  • 71
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    Publication Date: 2011-08-18
    Description: A study was performed to determine the effects of a mercury ion thruster plume on an S-band telecommunication carrier. Experiments were carried out on a 30 cm thruster in a JPL test chamber. Results from simple analytical models were compared with the above measurements and major discrepancies were discovered. Modifications to the electron density model provided a qualitative explanation, but further work is necessary for a quantitative answer. The results indicate the effects of the plume, on S and X Band telecommunications will be minor, with the possible exception of critical angle blockage.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 191-215
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  • 72
    Publication Date: 2011-08-18
    Description: An electric propulsion thrust system has the capability of providing a high specific impulse for long duration scientific missions in space. The EMI from the elements of an ion engine was characterized. The compatibility of ion drive electric propulsion systems with typical interplanetary spacecraft engineering was predicted.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 185-190
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  • 73
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    Publication Date: 2011-08-18
    Description: In order to properly assess the interaction of a spacecraft with the EMI environment produced by an ion thruster, the EMI environment was characterized. Therefore, radiated and conducted emissions were measured from a 30-cm mercury ion thruster. The ion thruster beam current varied from zero to 2.0 amperes and the emissions were measured from 5 KHz to 200 MHz. Several different types of antennas were used to obtain the measurements. The various measurements that were made included: magnetic field due to neutralizer/beam current loop; radiated electric fields of thruster and plume; and conducted emissions on arc discharge, neutralizer keeper and magnetic baffle lines.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 167-183
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  • 74
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    Publication Date: 2011-08-18
    Description: These facility produced ions are created by charge-exchange collisions between neutral atoms and energetic thruster beam ions. The result of the electron transfer is an energetic neutral atom and an ion of only thermal energy. There are true charge-exchange ions produced by collisions with neutrals escaping from the ion thruster and being charge-exchange ionized before the neutral intercepts the tank wall. The facility produced charge-exchange ions will not exist in space and therefore, represent a source of error where measurements involving ion thruster plasmas and their density are involved. The quantity of facility produced ions in a test chamber with a 30 cm mercury ion thruster was determined.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 147-166
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  • 75
    Publication Date: 2011-08-18
    Description: Under the proper conditions there is an end-effect of a long, cylindrical Langmuir probe which allows a significant increase in collected ion current when the probe is aligned with a flowing plasma. This effect was used to determine the charge-exchange plasma flow direction at various locations relative to the ion thruster. The ion current collected by the probe as a function of its angle with respect to the plasma flow allows determination of the plasma density and plasma flow velocity at the probe's location upstream of the ion thruster optics. The density values obtained from the ion current agreed to within a factor of two of density values obtained by typical voltage-current Langmuir probe characteristics.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 67-72
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  • 76
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    Publication Date: 2011-08-18
    Description: Biasing techniques and their application to the control of spacecraft potential is discussed. Normally when a spacecraft is operated with ion thrusters, the spacecraft will be 10-20 volts negative of the surrounding plasma. This will affect scientific measurements and will allow ions from the charge-exchange plasma to bombard the spacecraft surfaces with a few tens of volts of energy. This condition may not be tolerable. A proper bias system is described that can bring the spacecraft to or near the potential of the surrounding plasma.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Exptl. and Anal. Evaluation of Ion Thruster(Spacecraft Interactions; p 11-28
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  • 77
    Publication Date: 2011-08-18
    Description: Previous results on the tracking performance of two-channel Costas-type carrier synchronization loops are generalized and corrected, in order that they may be applied to several mixed-format cases. In particular, the mean-square phase jitter performance of these loops with active arm filters, synchronous or asynchronous symbol clocks, and arbitrary data formats on the two channels is examined. It is demonstrated that for each case, selection of the channel gain ratio, as motivated by the MAP estimation theory, does not guarantee optimum loop tracking performance: in some instances, a conventional single-channel Costas loop would outperform the two-channel version with the MAP choice of gain ratio. It is suggested that the gain ratio be chosen to directly minimize the mean-square phase tracking jitter which is equivalent to minimizing the loop's 'squaring loss'. This can, in some cases, improve the performance measure, although in all cases, the two-channel loop will still outperform the single-channel version.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-29; Sept
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  • 78
    Publication Date: 2011-08-18
    Description: Performance tests performed on a four-feed microstrip antenna and feed network are analyzed. Frequency response with and without amplifiers, an investigation of noise threshold, phase tracking, and jitter are included. Recommendations for further development of SPS power conversion modules are also included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 1; 28 p
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  • 79
    Publication Date: 2011-08-18
    Description: The microwave Scanning Beam Landing System's (MSBLS) performance in fog and rain was studied. The fog and rain effects on the Shuttle Ku-band system were determined. Specifically, microwave attenuation, beam distortion, and coordinate errors resulting from operation of the MSBLS in poor weather conditions were evaluated. The main physical processes giving rise to microwave attenuation were found to be absorption and scattering by water droplets. The general theory of scattering and absorption used is discussed and a listing of applicable computer programs is provided.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 1; 33 p
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  • 80
    Publication Date: 2011-08-18
    Description: This paper examines the performance of coherent QPSK and QASK systems combined with FH or FH/PN spread spectrum techniques in the presence of partial-band multitone or noise jamming. The worst-case jammer and worst-case performance are determined as functions of the signal-to-background noise ratio (SNR) and signal-to-jammer power ratio (SJR). Asymptotic results for high SNR are shown to have a linear dependence between the jammer's optimal power allocation and the system error probability performance.
    Keywords: COMMUNICATIONS AND RADAR
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  • 81
    Publication Date: 2016-06-07
    Description: A redundant frequency and time distribution system provides a multiplicity of isolated outputs, all of which are derived from three atomic frequency standards. The distribution system monitors input parameters of the signals coming from the Cesium Standards and selects one to be the primary standard, phase locks an internal oscillator which has excellent aging characteristics in the open loop mode and acts as a filter to provide phase noise improvement, and generates 1 megahertz and 100 kHz by direct synthesis. Additionally, the system distributes RF and timing signals consisting of 5 MHz, 1 MHz, 100 kHz, BCD Time-of-Day, 1 pps and 1 ppm.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval. and Planning; p 765-783
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  • 82
    Publication Date: 2016-06-07
    Description: The frequency behavior of AT-cut quartz crystals irradiated by X -, gamma rays and fast neutrons. Initial instability in frequency for gamma and neutron irradiated crystals was found. All the different radiations first give a negative frequency shift at lower doses which are followed by positive frequency shift for increased doses. Results are explained in terms of the fundamental crystal structure. Applications of the frequency results for radiation hardening are proposed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 829-849
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  • 83
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    Publication Date: 2016-06-07
    Description: A high performance 5 MHz distribution system is described which has extremely low phase noise and jitter characteristics and provides multiple buffered outputs. The system is completely redundant with automatic switchover and is self-testing. Since the 5 MHz reference signals distributed by the NATO III distribution system are used for up-conversion and multiplicative functions, a high degree of phase stability and isolation between outputs is necessary. Unique circuit design and packaging concepts insure that the isolation between outputs is sufficient to quarantee a phase perturbation of less than 0.0016 deg when other outputs are open circuited, short circuited or terminated in 50 ohms. Circuit design techniques include high isolation cascode amplifiers. Negative feedback stabilizes system gain and minimizes circuit phase noise contributions. Balanced lines, in lieu of single ended coaxial transmission media, minimize pickup.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 743-764
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  • 84
    Publication Date: 2016-06-07
    Description: The effects of source structure on radio interferometry measurements were investigated. The brightness distribution measurements for ten extragalactic sources were analyzed. Significant results are reported.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 635-645
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  • 85
    Publication Date: 2019-06-28
    Description: The analyses of Bruno (1973) and Blanchard (1974, 1975) of the effects of strong radio-frequency interference on the behavior of a phase-locked loop are examined in detail. The lock constraints derived directly from a steady-state trial solution by Bruno and those derived with simplifying assumptions from the same trial solution by Blanchard are compared, and circumstances which may be accommodated by the results of Bruno but not those of Blanchard are pointed out. An explicit approximation is then derived which extends the closed-form approximation of Bruno for the loop phase error to the entire lock region. Results are illustrated for a loop filter representative of a phase-locked loop in a deep space network receiver.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-29; June 198
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  • 86
    Publication Date: 2019-06-28
    Description: Microwave propagation delay through the troposphere is studied as a means of estimating the adverse effect of atmospheric water vapor on the accuracy of measurements made with very long baseline interferometry. Vertical profiles of temperature and water vapor density were obtained from a total of 240 radiosonde launches taken simultaneously at three New England locations in 1974; all studies were made at the 19 and 22.2 GHz frequency operating range of the radiometers. The wet path length in the zenith direction could be estimated from the surface water vapor density to an accuracy of 5 cm for the summer data and 2 cm for winter data, and with the brightness temperatures, it could be estimated to an accuracy of 0.3 cm. Two dual-frequency radiometers were also used to determine the accuracy of prediction of the path length from real radiometry data. The rms error for the estimation of wet path length from surface meteorological parameters was 3.2 cm, and for the radiometer brightness temperatures the rms error was 1.5 cm.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 16; Mar
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  • 87
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    Publication Date: 2019-06-28
    Description: A procedure is presented for calculating the power spectrum of the class of digital continuous-phase signals known as multi-h phase codes. These signals have been shown to have attractive power advantages over other uncoded digital schemes such as QPSK, and represent a bandwidth-efficient alternative to other coding techniques. The method is general, handling M-ary signaling, various frequency pulse shapes, and arbitrary sets of modulation indices. Numerical results are shown for several specific codes. In addition, the issue of spectral lines is resolved, and simple spectral approximations are developed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-29; Mar. 198
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  • 88
    Publication Date: 2019-06-28
    Description: Shot noise places a practical limit on the spatial and temporal resolution of lidar photocount data. A 2-D signal-processing technique that utilizes spatial and temporal filtering to reduce shot noise and increase resolution is described. The technique is applied to sodium lidar data collected during the fall of 1979 over Urbana, Illinois. Temporal filtering is shown to enhance the spatial resolution of the sodium profiles significantly by reducing shot noise by more than 10 dB. The signal-processing technique is applicable to a wide variety of lidar data.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Optics Letters; 6; Apr. 198
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  • 89
    Publication Date: 2019-06-28
    Description: The volume provides an introduction to antennas and probes embedded within or near material bodies such as the earth, the ocean, or a living organism. After a fundamental analysis of insulated and bare antennas, an advanced treatment of antennas in various media is presented, including a detailed study of the electromagnetic equations in homogeneous isotropic media, the complete theory of the bare dipole in a general medium, and a rigorous analysis of the insulated antenna as well as bare and insulated loop antennas. Finally, experimental models and measuring techniques related to antennas and probes in a general dissipative or dielectric medium are examined.
    Keywords: COMMUNICATIONS AND RADAR
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  • 90
    Publication Date: 2019-06-28
    Description: A frequency division multiple access (FDMA) 30/20 GHz satellite communications architecture without on-board baseband processing is investigated. Conceptual system designs are suggested for domestic traffic models totaling 4 Gb/s of customer premises service (CPS) traffic and 6 Gb/s of trunking traffic. Emphasis is given to the CPS portion of the system which includes thousands of earth terminals with digital traffic ranging from a single 64 kb/s voice channel to hundreds of channels of voice, data, and video with an aggregate data rate of 33 Mb/s. A unique regional design concept that effectively smooths the non-uniform traffic distribution and greatly simplifies the satellite design is employed. The satellite antenna system forms thirty-two 0.33 deg beam on both the uplinks and the downlinks in one design. In another design matched to a traffic model with more dispersed users, there are twenty-four 0.33 deg beams and twenty-one 0.7 deg beams. Detailed system design techniques show that a single satellite producing approximately 5 kW of dc power is capable of handling at least 75% of the postulated traffic. A detailed cost model of the ground segment and estimated system costs based on current information from manufacturers are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-165419 , NASA/LERC-C-49029-D , MTR-8311
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  • 91
    Publication Date: 2019-06-28
    Description: A liquid injection thrust vector control (LITVC) system for the shuttle solid rocket booster (SRB) was analyzed. The LITVC was compared with the SRB baseline flexible seal. A table of LITVC advantages and disadvantages is presented. It is concluded that the LITVC performs well at low to moderate duty cycles, but not for high duty cycle requirements.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TP-1912 , M-354
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  • 92
    Publication Date: 2019-06-28
    Description: Analytical and experimental results are presented of the effects of receiver tracking phase error, caused by weak signal conditions on either the uplink or the downlink or both, on the performance of the concatenated Reed-Solomon (RS) Viterbi channel coding system. The test results were obtained under an emulated S band uplink and X band downlink, two way space communication channel in the telecommunication development laboratory of JPL with data rates ranging from 4 kHz to 20 kHz. It is shown that, with ideal interleaving, the concatenated RS/Viterbi coding system is capable of yielding large coding gains at very low bit error probabilities over the Viterbi decoded convolutional only coding system. Results on the effects of receiver tracking phase errors on the performance of the concatenated coding system with antenna array combining are included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-164857 , JPL-PUB-81-62
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  • 93
    Publication Date: 2019-06-28
    Description: The consolidation on the existing Deep Space Network (DSN) and colocated Goddard Spaceflight Tracking and Data Network (STDN) stations into a multiple antenna array is discussed. Each site includes a signal processing center (SPC) centered in an array of four or five antennas each located within approximately 300 to 800 meters of the SPC. A central frequency and timing system (FTS) located in the SPC contains reference frequency, timing and time code generation, and distribution equipment for both the SPC and each antenna with its associated front end antenna control building. The reference frequency distribution and clock equipment are driven by a hydrogen maser as the prime frequency standard with cesium beam frequency standard as the secondary.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 591-614
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  • 94
    Publication Date: 2019-06-28
    Description: Growing demands on the frequency spectrum have increased the possibility of radio frequency interference (RFI). Various approaches to obtain in orbit RFI data are compared; this comparision indicates that the most practical way to obtain RFI data for a desired orbit (such as a geostationary orbit) is through the extrapolation of in orbit RFI measurements by a low orbit satellite. It is concluded that a coherent RFI program that uses both experimental data and analytical predictions provides accurate RFI data at minimal cost.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-164531 , JPL-PUB-81-34
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  • 95
    Publication Date: 2019-06-28
    Description: The position of a terrestrial RF source is determined from a geostationary, synchronous satellite by scanning the beam of a narrow beam width antenna in first and second orthogonal directions over a region including the source. The peak level of energy transduced by the antenna in each of the scanning directions is detected and correlated with the scanning position of the beam by feeding the output of a detector responsive to the transduced signal to an indicator of an X-Y recorder. The X and Y axes of the recorder are scanned in synchronism with the beam being respectively scanned in the first and second directions to form X and Y traces on which are indicated the detected peak position in each of the scanning directions. The source position is determined from an intersection of lines drawn parallel to the X and Y axes and including the detected peak position of each trace.
    Keywords: COMMUNICATIONS AND RADAR
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  • 96
    Publication Date: 2019-06-28
    Description: Because of the advantage of the Advanced Expander Cycle Engine brought out in initial studies, further design optimization and comparative analyses were undertaken. The major results and conclusion derived are summarized. The primary areas covered are (1) thrust chamber geometry optimization, (2) expander cycle optimization, (3) alternate low thrust capability, (4) safety and reliability, (5) development risk comparison, and (6) cost comparisons. All of the results obtained were used to baseline the initial design concept for the OTV Advanced Expander Cycle Engine Point Design Study.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-161699 , REPT-32999-F-E1
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  • 97
    Publication Date: 2019-06-28
    Description: The theoretical operational parameters for the workable satellite power system were examined. The system requirements for efficient transmission and reception of an environmentally benign microwave beam were determined.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-160921
    Format: application/pdf
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  • 98
    Publication Date: 2019-06-28
    Description: The deformation process observed in the hot gas side wall of rocket combustion chambers was investigaged for three different liner materials. Five thrust chambers were cycled to failure by using hydrogen and oxygen as propellants at a chamber pressure of 4.14 MN/cu m. The deformation was observed nondestructively at midlife points and destructively after failure occurred. The cyclic life results are presented with an accompanying discussion about the problems of life prediction associated with the types of failures encountered in the present work. Data indicating the deformation of the thrust chamber liner as cycles are accumulated are presented for each of the test thrust chambers. From these deformation data and observation of the failure sites it is evident that modeling the failure process as classic low cycle thermal fatigue is inadequate as a life prediction method.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TP-1834 , E-553
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  • 99
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    In:  CASI
    Publication Date: 2019-06-28
    Description: Analytical models to predict performance and operating characteristics of dual nozzle concepts were developed and improved. Aerodynamic models are available to define flow characteristics and bleed requirements for both the dual throat and dual expander concepts. Advanced analytical techniques were utilized to provide quantitative estimates of the bleed flow, boundary layer, and shock effects within dual nozzle engines. Thermal analyses were performed to define cooling requirements for baseline configurations, and special studies of unique dual nozzle cooling problems defined feasible means of achieving adequate cooling.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-161677 , REPT-33553F
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  • 100
    Publication Date: 2019-06-28
    Description: Optical data handling methods are studied as applicable to payload communications checkout and monitoring. Both payload umbilicals and interconnecting communication lines carrying payload data are examined for the following: (1) ground checkout requirements; (2) optical approach (technical survey of optical approaches, selection of optimum approach); (3) survey and select components; (4) compare with conventional approach; and (5) definition of follow on activity.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-CR-166825-VOL-2
    Format: application/pdf
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