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  • Other Sources  (987)
  • COMMUNICATIONS AND RADAR  (987)
  • 2020-2022
  • 1975-1979  (987)
  • 1
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    Propagation predictions for the HF-range by the Research Institute of the Deutsche Bundespost (1979)
    In:  CASI
    Details
    Publication Date: 2009-11-16
    Description: Long term and short term HF propagation prediction service is described. The long term prediction method is computer based. The short term prediction method is still a manual method which relies mainly on a number of continuous field strength recordings and on the forecaster's ability to interpret the recordings and to combine this information with all available solar-geophysical data. Examples of the predictions are given and are compared with actually observed HF propagation conditions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 25-43
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  • 2
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    A circuit model for electromagnetic properties of waveguide arcs (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: A dielectric model of waveguide arcs is presented to relate measurable electromagnetic quantities to the physical parameters characterizing the breakdown process.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 193-195
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  • 3
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    Assessment of 20 kW S-band transmitter (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The performance history of the 20-kW S-band transmitter, installed at three 64-meter antennas and six 26-meter antennas in the DSN, is reviewed. A number of failures and discrepancy reports are characteristic of the wearout phase of a failure curve. The type of failures are reviewed and four options toward reducing the number and cost of failures are reviewed. These are: existing (no change), refurbish, redesign and replacement. The options are compared on a ten year life cycle cost basis using FY77 expenditures for existing equipment as a base. It was concluded that benefits, in terms of reduction of outrage time, increase with an increase of expenditure toward improvement.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 186-192
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  • 4
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    Microwave time delays in the DSN 34- and 64-meter antennas (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The results and methods used to derive data for the recent changes to the DSN 34- and 64-m stations at both S- and X-band frequencies are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 183-185
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  • 5
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    DSS 13 antenna monitor system (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The development of a monitor system for the DSS 13 antenna is presented. The system checks for accumulator pressures, differential pressures, wind velocity, power supplies, fluid temperatures, and fluid levels. It was concluded that the system performed properly in high winds and correctly reported all malfunctions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 138-140
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  • 6
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    Carrier tracking loop performance in the presence of strong CW interference (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: Research on the behavior of the carrier tracking loop exposed to a continuous wave irradiation along with Bruno's closed form of approximation for the loop phase error are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 130-137
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  • 7
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    Costas loop demodulation of suppressed carrier BPSK signals in the DSN environment: Experimental results obtained at TDL (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: Suppressed carrier binary phase-shift keyed (BPSK) signalling is currently being considered as a design alternative for future DSN telemetry in the multimegabit range. Carrier tracking of such signals is usually achieved by a Costas loop, as opposed to the ordinary phase lock loop. A Costas loop capable of demodulating BPSK signals with data rates up to 1 Msps was designed and constructed and its Doppler tracking performance with respect to a Block 3 receiver was tested at the Telecommunications Development Laboratory (TDL). The compatibility of suppressed carrier signalling with the current radiometric system, specifically Doppler tracking and ranging, was investigated. The experimental results obtained to-date with respect to Doppler tracking are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 94-104
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  • 8
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    Feasibility of inertialess conscan utilizing modified DSN feedsystems (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The closed-loop conical-scan (conscan) technique has proven to be a useful method for pointing the DSN antennas more accurately than is possible by open-loop methods. As presently implemented, the antenna beam is scanned about the received signal direction by physical movement of the antenna. While straightforward, this approach has at least two disadvantages. Firstly, because of structural distortions, finite angle encoder resolution, and drive servo response, the actual antenna beam direction only approximates the commanded beam direction. Secondly, because of the large mass moved during scan, the rate of scan is severely restricted. If there are significant gain or signal level variations during a scan period, the conscan system interprets these variations as antenna pointing error. Both of these disadvantages would be alleviated in an inertialess conscan system in which the beam scanning was performed electronically. Recently, standard JPL antenna feedhorn software was upgraded to calculate, among other things, asymmetric corrugated horn radiation patterns of the type that would be needed for electronic beam scan. The required horn excitation is discussed and the results were described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 85-93
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  • 9
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    Antenna feedhorn software upgrade (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: The HYBRIDHORN computer program was developed to serve as an item of general purpose antenna feedhorn design and analysis software. The formulation contains a small flare angle approximation which is subject to question for designs such as the S- and X-band feedhorn. Additionally, the original formulation did not allow azimuthal variation indexes other than unity. The HYBRIDHORN program was upgraded to correct both of these deficiencies. A large flare angle formulation was found. In the upgrade, all of the major program elements were converted to Univac 1108 compatible structured FORTRAN (SFTRAN) for ease of software maintenance. The small and large angle formulations are described and sample numerical results are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 75-84
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  • 10
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    Some effects of quantization on a noiseless phase-locked loop (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: If the VCO of a phase-locked receiver is to be replaced by a digitally programmed synthesizer, the phase error signal must be sampled and quantized. Effects of quantizing after the loop filter (frequency quantization) or before (phase error quantization) are investigated. Constant Doppler or Doppler rate noiseless inputs are assumed. The main result gives the phase jitter due to frequency quantization for a Doppler-rate input. By itself, however, frequency quantization is impractical because it makes the loop dynamic range too small.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 58-66
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  • 11
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    Recovering the spectrum of a narrow-band process from syncopated samples (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-01
    Description: A nonuniform sampling strategy, phase quadrature sampling, in which a process of bandwith B is sampled at rate B in each of two channels where the two channels are pi/2 out of phase at frequency B is described. Phase quadrature sampling is a special case of sampling, where the phase between channels is fixed but arbitrary. A simple method for recovering the spectrum of the input process from syncopated samples is derived. The derivation indicates what values of phase between channels result in lossless sampling.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 47-50
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  • 12
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    Effects of D region ionization on radio wave propagation (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The effects of anomalous D region ionization upon radio wave propagation are described for the main types of disturbances: sudden ionospheric disturbances, relativistic electron events, magnetic storms, auroral disturbances, polar cap events, and stratospheric warmings. Examples of radio wave characteristics for such conditions are given for the frequencies between the extremely low (3-3000 Hz) and high (3-30 MHz) frequency domains. Statistics on the disturbance effects and radio wave data are given in order to contribute towards the evaluation of possibilities for predicting the radio effects.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 617-654
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  • 13
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    Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 182-204
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  • 14
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    Estimation of solar flame influence on radio circuit transmission loss (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A provisional method for determining the hours and frequencies at which solar flares cause major radiopath absorption increase is presented. This technique is incorporated in a computer program for monthly radio propagation prediction.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 67-71
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  • 15
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    An empirical spectral bandwidth model for superior conjunction (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The downlink signal from spacecraft in superior solar conjunction phases suffers a great reduction in signal-to-noise ratio. Responsible in large part for this effect is the line broadening of the signal spectrum. An analytic empirical expression was developed for spectral bandwidth as a function of heliocentric distance from 1 to 20 solar radii. The study is based on spectral broadening data obtained from the superior conjunctions of Helios 1 (1975), Helios 2 (1976), and Pioneer 6 (1968). The empirical fit is based in part on a function describing the electron content in the solar corona.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 216-223
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  • 16
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    Radio frequency interference between spacecraft in different missions (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The possibility of separately receiving signals transmitted in a common frequency band from spacecraft in different missions was studied. For the mission pairs that were examined, co-channel operation without interference is generally possible. For some mission pairs, co-channel interference would occur during brief post-launch periods.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 180-184
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  • 17
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    System performance testing of the DSN radio science system, Mark 3-78 (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: System performance tests are required to evaluate system performance following initial system implementation and subsequent modification, and to validate system performance prior to actual operational usage. Non-real-time end-to-end Radio Science system performance tests are described that are based on the comparison of open-loop radio science data to equivalent closed-loop radio metric data, as well as an abbreviated Radio Science real-time system performance test that validates critical Radio Science System elements at the Deep Space Station prior to actual operational usage.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 129-133
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  • 18
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    Deep space telecommunications and the solar cycle: A reappraisal (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Observations of density enhancement in the near corona at solar cycle (sunspot) maximum have rather uncritically been interpreted to apply equally well to the extended corona, thus generating concern about the quality of outer planet navigational data at solar cycle maximum. Spacecraft have been deployed almost continuously during the recently completed solar cycle 20, providing two powerful new coronal investigatory data sources: (1) in-situ spacecraft plasma measurements at approximately 1 AU, and (2) plasma effects on monochromatic spacecraft signals at all signal closest approach points. A comprehensive review of these (solar cycle 20) data lead to the somewhat surprising conclusions that for the region of interest of navigational data, the highest levels of charged particle corruption of navigational data can be expected to occur at solar cycle minimum, rather than solar cycle maximum, as previously believed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 110-124
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  • 19
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    PROPHET: An applicaton of propagation forecasting principles (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A propagation assessment and forecasting terminal, PROPHET, is described. The terminal is a key element of the environmental prediction and assessment system which uses real time solar/geophysical data to provide real time knowledge of propagation conditions. The terminal uses models to translate data from satellite and ground based sources into performance predictions for specific systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 312-321
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  • 20
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    Radio disturbance warning issuance system (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A radio disturbance warning issuance system was introduced in the Hiraiso Branch of the Radio Research Laboratories in 1972 to reconstruct the current radio disturbance warning service as a social information service. A description of the new ideas which were experimentally systematized by means of an electronic computer is presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 223-228
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  • 21
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    Low-noise receivers: S-band parametric up converter development (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The combination of a cryogenically-cooled parametric upconverter and a higher frequency maser post amplifier was proposed as a method of achieving maser-like receiver noise temperatures over much larger instantaneous bandwidths and tuning ranges than are presently obtainable with masers in the range of 1 to 18 GHz. An experimental 2.0- to 2.5-GHz parametric upconverter/maser system was developed to explore these possibilities. Initial tests of this system resulted in an effective input noise temperature of 3.1 K at 2295 MHz and 3.2 K at 2388 MHz. The parametric upconverter logged over 1500 hours at 4.5 K and underwent 5 thermal cycles (300 K to 4.5 K to 300 K) without degradation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 31-47
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  • 22
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    Symbol synchronizer assembly instability study, part 2 (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Data processing to develop a third-order phase model and to translate all such processed data to the frequency realm for further analysis was described. The frequency study yields a long frequency modulation (FM) drift sinusoid (1600-sec period), an impressed secondary drift wave with a period of about 116 sec, and a set of even harmonics of twice the ramp period-the latter arising from, and used to modify, the phase detector model. The result is applied secondarily to estimate the strong-signal SSA phase detector response "out-of-lock." Finally, the main drift components are verified against all available data, and the result is used to estimate minimum lock conditions and the SSA drift effect under normal operating modes. The instability problem appears marginally resolvable if the acquisition technique is modified.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 222-230
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  • 23
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    Corruption of radio metric Doppler due to solar plasma dynamics: S/X dual-frequency Doppler calibration for these effects (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Doppler data from Mariner 6, 7, 9, and 10 and Pioneer 10 and 11 were discussed and the rms noise level for various sun-earth-probe angles were shown. The noise levels of both S- and X-band Doppler data for sun-earth-probe angles smaller than 20 deg were observed to be orders of magnitude greater than nominal. Such solar plasma-related Doppler degradation reduced the Mariner 10-Mercury 11 encounter navigation accuracy by nearly a factor of 10. Furthermore, this degradation was shown to be indirectly related to plasma dynamics and not a direct measure of the dynamics.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 88-101
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  • 24
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    Performance of DSS 13 26-m antenna at X-band (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The X-band low-noise antenna (XLA) measurement feedcone was operated on the DSS 13 26-m antenna at Goldstone, California, during June 1975 to evaluate, primarily, the overall system efficiency. Radio sources were selected, commonly accepted values of flux density established, and measurements completed, and some conclusions were drawn. The antenna system presently suffers from poor pointing stability. On the other hand, the previously welded and rebolted main reflector has remained quite stable over a period of approximately 5 years.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 113-118
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  • 25
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    Ionosphere-reflected propagation (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The predictability of those ionospheric parameters relevant to ionosphere-reflected communications is considered along with their optimum utilization. Several excellent original articles and review papers which have been published from time to time dealing with the long term and short term forecasting of ionospheric parameters, radio systems, and modelling needs for ionospheric communications, are covered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 203-216
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  • 26
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    Transionospheric propagation predictions (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The current status and future prospects of the capability to make transionospheric propagation predictions are addressed, highlighting the effects of the ionized media, which dominate for frequencies below 1 to 3 GHz, depending upon the state of the ionosphere and the elevation angle through the Earth-space path. The primary concerns are the predictions of time delay of signal modulation (group path delay) and of radio wave scintillation. Progress in these areas is strongly tied to knowledge of variable structures in the ionosphere ranging from the large scale (thousands of kilometers in horizontal extent) to the fine scale (kilometer size). Ionospheric variability and the relative importance of various mechanisms responsible for the time histories observed in total electron content (TEC), proportional to signal group delay, and in irregularity formation are discussed in terms of capability to make both short and long term predictions. The data base upon which predictions are made is examined for its adequacy, and the prospects for prediction improvements by more theoretical studies as well as by increasing the available statistical data base are examined.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 217-245
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  • 27
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    Tracking error of 100-m antenna due to wind gust (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: A procedure is shown to derive root-mean-square tracking error for an antenna system in response to wind gust loading. Example calculations are illustrated for the design of a proposed 100 m antenna. The effect of wind gust correlation is also considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 94-101
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  • 28
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    The X-band low noise antenna measurement cone (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: An X-band low-noise receiving cone with 17-MHz instantaneous bandwidth was built to evaluate the 26-m antenna at the Venus Station (DSS 13), Goldstone, California, at X-band frequencies, and also to provide a means for precise radio source calibrations in this frequency range. These measurments are necessary to provide more accurate antenna gain performance calibrations for the 64-m antenna subnet. The zenith system temperatures with the cone on the ground and on the antenna are 17.5 and 20.8 K, respectively.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 105-112
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  • 29
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    Radio propagation prediction services in Japan (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Japanese prediction services for HF radio communications are outlined in relation to prediction method, performance and evaluation. The current prediction is based on the CCIR interim method with some modifications matching to a computer system. The principal service is the monthly median prediction issued regularly three months in advance for various communication circuits. A daily prediction for short distance circuits is being prepared by using real time ionospheric sounding data. An evaluation theory and practice is expected to be introduced in the future prediction service.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 212-222
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  • 30
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    Long term solar activity and ionospheric prediction services rendered by the National Physical Laboratory, New Delhi (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The data base used in solar and ionospheric prediction services is described. Present prediction techniques are discussed and compared with actual observations. Future prediction techniques using computers are also discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 118-133
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  • 31
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    The French short term radiopropagation predictions in the decameter band (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Weekly and daily predictions of the ionospheric characteristics relevant to radio propagation are considered. A description of the techniques involved is given as well as examples showing how the prediction messages are prepared. The short term predictions are confined to restricted geographical areas and are relevant to radio circuits whose terminators are both located inside the same zone. They can be used with a reasonable approximation for circuits less than 3000 km of length whose reflection point lies within a given zone.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 12-24
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  • 32
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    CCIR papers on telecommunications for deep space research (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Mission requirements, equipment factors, and link performance define the frequency bands that are preferred for deep space research using manned and unmanned spacecraft. The preferred bands and selection considerations are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 164-179
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  • 33
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    New X-band microwave equipment at the DSN 64-meter stations (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The performance and capabilities of the DSN 64 m antennas at X-band are considered including extensive modifications to the XRO cone assemblies. The changes include a feed assembly with a dual hybrid mode horn and orthogonal mode junction, dual traveling wave masers, and receiver mode selector.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 126-128
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  • 34
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    Simultaneous dual-frequency, round-trip calibration of Doppler data with application to radio science experiments (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Simultaneous dual-frequency, round-trip calibration of Doppler data is discussed in light of unequal spacecraft turnaround ratios at S- and X-band. The impact of unequal turnaround ratios on calibration accuracies in the specific cases of the Gravitational Wave Detection Experiment and the Solar Gravitational Quadrupole Moment Experiment is considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 49-54
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  • 35
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    Microcontroller for automation application (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The description of a microcontroller currently being developed for automation application was given. It is basically an 8-bit microcomputer with a 40K byte random access memory/read only memory, and can control a maximum of 12 devices through standard 15-line interface ports.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 144-147
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  • 36
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    DSS 14 X-band radar feedcone (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: A high-power 400-kW continuous-wave (CW) X-band radar feed system was described for use with the Goldstone, California, 64-m DSS 14 antenna system. Design considerations, their solutions, and final system testing are discussed. The radar system, unique in terms of antenna size, radiated power, and efficiency, became operational in December 1974.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 119-131
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  • 37
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    Radio bridges through the universe (1975)
    In:  CASI
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    Publication Date: 2006-01-11
    Description: The design and operation of quantum amplifiers to detect extremely weak radio signals from space are discussed. Special attention was given to amplifier performance in planetary radar ranging studies, super-long baseline radio interferometry, and remote space communications. Amplifier sensitivity was also examined.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Mod. Achievements of Cosmonautics (NASA-TT-F-16221); p 63-67
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  • 38
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    Some proposed experiments with the Communications Technology Satellite (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The satellite (CTS) is tentatively scheduled to be launched in January 1976. It will be available for educational and societal experimentation early in 1977. This paper will outline some of the educational experiments involving the CTS. The major object of the experiments is to assess the communications and educational implications of the CTS in northern Ontario; the existing communications facilities for this region of approximately 725,000 sq km (inhabited largely by native people) are extremely limited. It is expected to assess the extent to which: (1) a satellite communications system might resolve the communications deficiency, (2) the native people will use the experimental facility, and (3) health and general educational programs, especially utilizing the interactive mode, will be viable.
    Keywords: COMMUNICATIONS AND RADAR
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  • 39
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    Graphical derivations of radar, sonar, and communication signals (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The designer of a communication system often has knowledge concerning the changes in distance between transmitter and receiver as a function of time. This information can be exploited to reduce multipath interference via proper signal design. A radar or sonar may also have good a priori information about possible target trajectories. Such knowledge can again be used to reduce the receiver's response to clutter (MTI), to enhance signal-to-noise ratio, or to simplify receiver design. There are also situations in which prior knowledge about trajectories is lacking. The system should then utilize a single-filter pair which is insensitive to the effects induced by relative motion between transmitter, receiver, and reflectors. For waveforms with large time-bandwidth products, such as long pulse trains, it is possible to graphically derive signal formats for both situations (trajectory known and unknown). Although the exact form of the signal is sometimes not specified by the graphical procedure, the problem in such cases is reduced to one which has already been solved, i.e., the generation of an impulse equivalent code.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-11; Jan. 197
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  • 40
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    On improved ranging (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The use of a 1 MHz range code and a narrow-passband IF filter reduces waveform distortion error by a factor of as much as 20. Along with this improvement in ranging precision, ranging accuracy is enhanced by nullifying many errors caused by equipment vagaries. The IF filter and concomitant modification of ranging system software (and in the case of the planetary ranging assembly, hardware) are the most cost-effective way of improving the current generation ranging system.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 40-44
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  • 41
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    JPL 2-to-the-20th-power channel 300 MHz bandwidth digital spectrum analyzer (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A million (two to the 20th power) channel, 300 MHz bandwidth, digital spectrum analyzer was considered. The design, fabrication, and maintenance philosophy of the modular, pipelined, fast fourier transform (FFT) hardware are described. The spectrum analyzer will be used to examine the region from 1.4 GHz to 26 GHz for radio frequency interference which may be harmful to present and future tracking missions of the Deep Space Network. The design has application to the search for extraterrestrial intelligence signals and radio science phenomena.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 57-61
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  • 42
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    On estimating the phase of a periodic waveform in additive Gaussian noise, part 1 (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Motivated by recent advances in technology, a new look is taken at the problem of estimating the phase of a periodic waveform in additive Gaussian noise. The maximum a posteriori probability criterion with signal space interpretation is used to obtain the structures of optimum and some suboptimum phase estimators for the following cases: (1) known constant frequency and unknown constant phase with an a priori distribution; (2) unknown constant frequency and phase with a joint a priori distribution; (3) frequency a parameterized function of time with a joint a priori distribution on parameters and phase and (4) frequency a Gaussian random process.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 152-164
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  • 43
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    CCIR paper on the radiocommunications requirements for systems to search for extraterrestrial life (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The allocation and propagation of radio frequency bands to be used in the search for extraterrestrial intelligence is considered. Topics discussed include: propagation factors; preferred frequency bands; system characteristics and requirements; and interference.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 224-244
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  • 44
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    Pioneer Venus 1978 Deep Space Network telecommunications compatibility test program status (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The Pioneer Venus 1978 flight project Deep Space Network telecommunications compatibility test program is discussed. Subsystem design tests performed during April 1977 and November 1977 are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 39-100
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  • 45
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    A radio lens in the ionosphere (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Using a modified version of the classical Cornu spiral, fading patterns in agreement with observations of radio signals on 140 and 360 MHz from the geostationary satellite ATS6, have been obtained. The particular fading patterns chosen show modulated quasi-periodic fading before and after a deep central minimum. It is shown that a cylindrical lens in the ionosphere required to produce this is only about 100 m across (an order of magnitude smaller than the size of the pattern on the ground) and if it were circular in cross-section would have a maximum plasma frequency of over 40 MHz. This suggests the reason why calculations based on a transparent phase screen did not give the observed fading pattern for 40 MHz signals. It was not possible to deduce the height of the lens above the ground, though we would incline to an E-region origin.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Mar. 197
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  • 46
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    Limitations on oceanographic use of beam-limited target-referenced radars (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A general development is undertaken to determine the limitations on the use of beam-limited target-referenced radars in the measurement of ocean wave height. This class of radars is concerned only with the range extent of the target, not the range to the target. The nonzero range extent of a flat waveless sea and the compounding effect of pointing errors due to radar platform instability cause difficulty in measuring low wave heights and impose a maximum operating altitude on such systems. It is seen that it is impractical to obtain accurate measurements for wave heights of interest at altitudes above those used by commercial aircraft (10,000 m). Additionally, the typical ratio of dominant wavelength to significant wave height (SWH) of 30 for wind-driven gravity waves imposes an upper limit on the SWH measurable for a given altitude and beamwidth.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-25; May 1977
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  • 47
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    Tracking performance of symbol synchronizers for Manchester coded data (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The implementation and tracking performance of symbol synchronizers for Manchester coded data is presented with motivation provided by maximum a posteriori (MAP) estimation theory. Certain physically relizable closed-loop structures, readily implemented in practice, are suggested by the theory for uncoded data symbols with arbitrary data transition probabilities. The tracking performance of these loops is optimized and comparisons are made among the various configurations over a wide range of system parameters. Although not the major intent of the paper, the acquisition problem is briefly addressed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-25; Apr. 197
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  • 48
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    An antenna for limited scan in one plane - Design criteria and numerical simulation (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Aperture illumination is synthesized through the use of overlapping subarrays with independently controlled excitations. Detailed analysis and design criteria are provided for a specific limited-scan antenna configuration scanning in one plane. The number of phase shifts is the theoretical minimum corresponding to specified aperture size and field of view. Beam pointing and width are approximately constant for moderate frequency variation, and ultralow sidelobes outside the field of view can be produced at the cost of a slight loss of illumination efficiency. Accurate aperture illumination control makes for excellent independently specified sum and difference patterns in beamforming.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-25; Mar. 197
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  • 49
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    Optimum performance of suppressed carrier receivers with Costas loop tracking (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The performance of suppressed carrier receivers with Costas loop tracking is optimized by proper choice of loop arm filter bandwidth. In particular, it is shown that for a variety of passive arm filter types, there exists, for a given data rate and data signal-to-noise ratio, an optimum filter bandwidth in the sense of minimizing the loop's squaring loss. For the linear theory case, this is equivalent to minimizing the loop's tracking jitter. When symbol synchronization is known, it is shown that by replacing the passive arm filters with active filters, i.e., integrate-and-dump circuits, one can achieve an improvement in carrier-to-noise ratio of as much as 4 to 6 dB depending on the passive arm filter type used for comparison and the value of data signal-to-noise ratio.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-25; Feb. 197
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  • 50
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    The scattering of electromagnetic pulses by a slit in a conducting screen (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A direct method for calculating the impulse response of a slit in a conducting screen is presented which is derived specifically for the analysis of transient scattering by two-dimensional objects illuminated by a plane incident wave. The impulse response is obtained by assuming that the total response is composed of two sequences of diffracted waves. The solution is determined for the first two waves in one sequence by using Green's functions and the equivalence principle, for additional waves in the sequence by iteration, and for the other sequence by a transformation of coordinates. The cases of E-polarization and H-polarization are considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-23; May 1975
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  • 51
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    Attenuation and space diversity statistics calculated from radar reflectivity data of rain (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-23; Mar. 197
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  • 52
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    The role of large particles in the formation of the radio echo (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The contribution to the total reflectivity of separate parts of a particle spectrum described by a gamma distribution is estimated. It is shown that the largest individual particles, whose percent concentration is 0.1 - 1, originate approximately 60 - 70% of the total reflectivity of the spectrum. Explanations are given of a number of effects which confirm the dominant role of large particles in the formation of the echo.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radar Meteorology (NASA-TT-F-14797); p 7-13
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  • 53
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    Networks systems and operations (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The application of wideband communication techniques for data links with satellites is discussed. A diagram of the demand assigned voice communications system is provided. The development of prototype integrated spacecraft paramps at S- and C-bands is described and the performance of space-qualified paramps is tabulated. The characteristics of a dual parabolic cylinder monopulse zoom antenna for use with the tracking and data relay satellite system (TDRSS) are analyzed. The development of a universally applicable transponder at S-band is reported. A block diagram of the major subassemblies of the S-band transponder is included. The technology aspects of network timing and synchronization of communication systems are to show the use of the Omega navigation system. The telemetry data compression system used during the Skylab program is evaluated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Significant Accomplishments in Sci. and Technol.; p 320-348
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  • 54
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    Communications and navigation (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The use of a computer simulation to quantitatively measure the distortion on a standard video test signal which experiences frequency modulation, filtering, and frequency demodulation is discussed. The process is applied to frequency modulated television systems for use with the ATS-F spacecraft. A block diagram of the system is presented. The characteristics of a millimeter wave space communication system are analyzed. The application of the Omega position location equipment (OPLE) for a global rescue net is reported. The development of a high speed photodetector for the neodynium yag laser system is discussed and the characteristics of the system are explained. The effects of gas pressure on waveguide laser tunability are examined.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Significant Accomplishments in Sci. and Technol.; p 250-289
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  • 55
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    Optimum design and performance of Costas receivers containing soft bandpass limiters (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: This paper investigates several key questions concerning the mechanization and design of a Costas receiver for reconstruction of a carrier from a suppressed carrier signal. For baseband NRZ encoded data symbols and a soft bandpass limiter preceding the loop, several design issues which are considered herein and which affect acquisition and tracking performance are: (1) The choice of an IF bandwidth. (2) The optimum choice of the Costas arm filter bandwidths as well as the spectral roll-off characteristics. (3) The optimum choice of loop bandwidth to data rate ratio for a given signal-to-noise ratio. (4) The signal suppression factor and the combined limiter-squaring loss. (5) The variations in loop bandwidth and damping with signal level. (6) The choice of the limiter transfer characteristic. (7) Performance degradation due to the presence of a limiter. Various new results in system design are presented and typical numerical results are given and graphically demonstrated in SNR regions of practical interest. The theory is applicable to the design of carrier reconstruction loops required in the implementation of spread spectrum communication receivers.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-25; Aug. 197
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  • 56
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    Polarization loss of a satellite - Data collection sensor link (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: It is noted that the stringent economy of data-collection systems consisting of several widely dispersed satellite-monitored sensor platforms can be partially achieved by using an inexpensive linearly polarized antenna on each platform and that due to Faraday rotation of the ionosphere, the satellite antenna must be circularly polarized to avoid a prohibitive polarization loss. The cumulative probability distribution of polarization loss between a linearly polarized platform antenna and an elliptically polarized satellite antenna is computed for satellite-antenna axial ratios of 3 and 4 dB. The results indicate that a polarization loss of 4.5 dB must be expected for a reliability of 85% and an axial ratio of 3 dB. It is suggested that the conventional assignment of a 3-dB polarization loss to the communication link considered may not insure the required link reliability.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-13; July 197
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  • 57
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    The Communications Technology Satellite /CTS/ Program (1976)
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    Publication Date: 2011-08-17
    Description: The purposes of the joint Canadian-U.S. Communications Technology Satellite (CTS) Program are (1) to conduct satellite communication systems experiments using the 12- and 14-GHz bands and low-cost transportable ground terminals, (2) to develop and flight test a power amplifier tube having a greater than 50% efficiency with a saturated power output of 200 W at 12 GHz, (3) to develop and flight test a lightweight extendible solar array with an initial power output greater than 1 kW, and (4) to develop and flight test a 3-axis stabilization system to maintain accurate antenna boresight positioning on a spacecraft with flexible appendages. Brief descriptions of these experiments and of the ground facilities are provided.
    Keywords: COMMUNICATIONS AND RADAR
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  • 58
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    Analysis of a discrete spectrum analyzer for the detection of radio frequency interference (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: As the radio frequency spectrum becomes increasingly overcrowded, interference with mission-critical DSN operations is rising at an alarming rate. To alleviate this problem the DSN is developing a wideband surveillance system for on-site detection and identification of potential sources of radio frequency interference (RFI), which will complement the existing frequency coordination activities. The RFI monitoring system is based on a wideband, multi-look discrete spectrum analyzer operating on fast Fourier transform principles. An extensive general statistical analysis is presented of such spectrum analyzers and derives threshold detection performance formulas for signals of interest. These results are then applied to the design of the RFI spectrum analyzer under development.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 83-98
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  • 59
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    Walsh transforms and signal detection (1977)
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    Publication Date: 2011-08-17
    Description: The detection of signals using Walsh power spectral estimates is analyzed. In addition, a generalization of this method of estimation is evaluated. The conclusion is that Walsh transforms are not suitable tools for the detection of weak signals in noise.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 127-131
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  • 60
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    Radio frequency interference from near-earth satellites (1977)
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    Publication Date: 2011-08-17
    Description: A pessimistic statistical model was developed for predicting the extent of radio frequency interference (RF1). Based on the assumptions underlying the model, DSN S-band operations can expect one RF1 interruption every 4.1 days, with the average incident lasting 24 s. This implies that 52 or more such satellites, with uncorrelated orbital trajectories, will cause in excess of 5 min of RF1 per day at a DSN station.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 69-77
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  • 61
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    Television applications of interline-transfer CCD arrays (1976)
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    Publication Date: 2011-08-17
    Description: The design features and characteristics of interline transfer (ILT) CCD arrays with 190 x 244 and 380 x 488 image elements are reviewed, with emphasis on optional operating modes and system application considerations. It was shown that the observed horizontal resolution for a TV system using an ILT image sensor can approach the aperture response limit determined by photosensor site width, resulting in enhanced resolution for moving images. Preferred camera configurations and read out clocking modes for maximum resolution and low light sensitivity are discussed, including a very low light level intensifier CCD concept. Several camera designs utilizing ILT-CCD arrays are described. These cameras demonstrate feasibility in applications where small size, low-power/low-voltage operation, high sensitivity and extreme ruggedness are either desired or mandatory system requirements.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 152-156
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  • 62
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    Television cameras employing solid-state imaging sensors for manned spacecraft applications (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The Space Shuttle television system incorporates a versatile complement of TV equipment which allows the positioning, quantity, and performance capabilities of the multiple TV cameras to vary as dictated by the particular mission. However, current TV camera technology employing glass enclosed, vacuum processed image sensors results in a bulky device that restricts its location and versatility. Problems and potential solutions that can be achieved through the employment of solid-state image sensors for both monochrome and color applications are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 126-128
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  • 63
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    Command detector SNR estimator and lock status monitor circuitry (1976)
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    Publication Date: 2011-08-17
    Description: A breadboard of the command detector signal-to-noise-ratio estimator and lock status monitor was built on a wire-wrap card. The breadboard was integrated with the standard command detector, and its performance was measured. The design, design constraints, and construction of the breadboard are described. The performance is shown to agree with the theoretical model.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 42-51
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  • 64
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    The scattering of obliquely incident plane waves from a corrugated conducting surface (1976)
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    Publication Date: 2011-08-17
    Description: A physical optics solution is presented for the scattering of plane waves from a perfectly conducting corrugated surface in the case of waves incident from an arbitrary direction and for an observer far from the surface. This solution is used to compute the radar cross section of the surface in the case of backscatter from irregular (i.e., stochastic) corrugations. An interesting feature of the solution is the occurrence of singularities in the scattered fields. These singularities appear to be a manifestation of focusing by the surface at its 'stationary' points. Whether or not the singularities occur in the solution depends on the manner in which one restricts the analysis to the far-field.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-24; Nov. 197
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  • 65
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    Modification of the DSN radio frequency angular tropospheric refraction model (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The previously derived DSN Radio Frequency Angular Tropospheric Refraction Model contained an assumption which was subsequently seen to be at a variance with the theoretical basis of angular refraction. The modification necessary to correct the model is minor in that the value of a constant is changed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 184-186
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  • 66
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    Synchronization strategies for RFI channels (1977)
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    Publication Date: 2011-08-17
    Description: An RFI channel to be a multiple-access channel is defined in which no sender can know when any other starts, and the problem of determining the relative phases of the senders at the receiver is studied. A new result is proved about binary DEBruijn sequences.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 103-108
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  • 67
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    Proportionality between Doppler noise and integrated signal path electron density validated by differenced S-X range (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Observations of Viking differenced S-band/X-band (S-X) range are shown to correlate strongly with Viking Doppler noise. A ratio of proportionality between downlink S-band plasma-induced range error and two-way Doppler noise is calculated. A new parameter (similar to the parameter epsilon which defines the ratio of local electron density fluctuations to mean electron density) is defined as a function of observed data sample interval (Tau) where the time-scale of the observations is 15 Tau. This parameter is interpreted to yield the ratio of net observed phase (or electron density) fluctuations to integrated electron density (in RMS meters/meter). Using this parameter and the thin phase-changing screen approximation, a value for the scale size L is calculated. To be consistent with Doppler noise observations, it is seen necessary for L to be proportional to closest approach distance a, and a strong function of the observed data sample interval, and hence the time-scale of the observations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 172-183
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  • 68
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    The Deep Space Network-Mariner Jupiter/Saturn 1977 flight project telecommunications compatibility (1977)
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    Publication Date: 2011-08-17
    Description: The DSN-Mariner Jupiter/Saturn 1977 telecommunications compatibility tests conducted during the periods 15-20 November 1976, 7-16 December 1976 and 5 January 1977, are an ongoing series of engineering level tests to determine the flight-ground interface compatibility and performance characteristics between these two systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 16-37
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  • 69
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    Radio frequency boresight analysis of the low cost 64-meter antenna (1976)
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    Publication Date: 2011-08-17
    Description: Configurations (two) of the reflector-only assemblies, using different width backup cones, are analyzed for RF boresight direction changes and wind distortions. The wider backup cone is best for minimum weight; however, there is an optimum weight which minimizes the RF boresight errors for a wind load that produces the maximum pitching moment of both configurations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 128-135
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    Magnitude of 64-m elevation axis movements due to alidade temperature changes (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In projected very-long baseline interferometry (VLBI) work a reference point for 64-m antennas is the intersection of the elevation and azimuth axes. A minimum-level effort at DSS 14 to determine the magnitude of the effect of diurnal changes in the temperature of the alidade legs on the height of the elevation axis is described. The thermal expansion between the lowest recorded temperature -3 C (27 F) and the highest, 36 C (97 F), over the period covered was 8.9 mm (0.35 in.).
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 41-44
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    Remote intensity fluctuation measurements with a laser Doppler radar (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A coaxial focused CW scanning laser Doppler velocimeter (SLDV) radar equipment applying heterodyne detection at 10.6 microns can measure intensity fluctuations under field conditions. The set includes a 20 W CO2 laser, a coaxial Cassegrainian telescope, standard heterodyne equipment, and a SAW spectrum analyzer with 100 kHz signal resolution. Operation of the equipment and techniques for taking remote measurements are described briefly. Applications to remote measurements of transverse component of wind speed, as a complement to the traditional Doppler method of determining axial velocity, are under study. SLDV equipment has been used in detection, tracking, and measurements of atmospheric turbulence associated with aircraft wing-tip vortices or with dust devils, and in measurement of general atmospheric wind profiles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Applied Optics; 15; Sept
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  • 72
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    New sidelobe envelopes for small aperture earth stations (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The advent of domestic satellite systems and technological improvements in both space and ground equipment makes the use of small aperture earth stations economically feasible and attractive for broadcast satellite applications. With increasing use of the orbit spectrum, there is some concern that broadcast satellite systems may not be able to obtain satisfactory allocations of this orbit-spectrum resource because of interference considerations. Specifically, interference calculations based on the present envelope result in comparatively large orbit spacings for broadcast satellites. Theoretical and experimental investigations of simple sidelobe suppression techniques, plus an analysis of experimental data on small aperture antennas, indicate that much better sidelobe performance can be obtained with a very small cost or performance penalty.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Broadcasting; BC-22; June 197
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  • 73
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    The input admittance of the rectangular cavity-backed slot antenna (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The input admittance of the rectangular cavity-backed slot antenna is investigated. The slot is assumed narrow so that the voltage distribution in its aperture is sinusoidal. Equations which represent the input admittance of this slot, backed by a rectangular cavity in which a single propagating wave is assumed to exist, are given. Calculations based on these representations are compared to available measured data. As the depth of the cavity increased the resonant frequency decreased and the bandwidth became narrower. Input admittance curves as a function of electrical slot length are also presented for several size cavities.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-24; May 1976
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  • 74
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    Selectable polarization at X-band (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The X-band feeds in the Deep Space Network were upgraded to include selectable polarization in time for the Voyager missions to the outer planets. The modified antenna feed has the following major items added: two circular waveguide rotary joints, drive motor and gear reducer, gear assembly, two microswitches, and a polarization control junction box. The overall length of the feed remains the same because circular waveguide spacing sections were designed into the original feed to readily permit such modifications. There is no significant increase in antenna noise temperature compared to the original feed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 177-180
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    DSS 13 automated antenna pointing subsystem phase 1 hardware (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An automated antenna pointing subsystem (APS) is being installed at DSS 13 as part of the unattended station project. The function of the APS is to track an instructed position with the 26 meter antenna and to monitor the antenna servo system and meteorological conditions to ensure a proper operational environment. This article discusses the now-completed first phase of the digital hardware portion of the APS development.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 100-109
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  • 76
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    X-band antenna gain and system noise temperature of 64-meter deep space stations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A set of measured data on the X-band performance of the three 64-meter deep space stations was obtained for use in future mission telecommunication design and predictions. The test configuration and measurement procedure is described. A method of modelling attenuation due to the atmosphere is given. Radio source brightness temperature and flux density are reviewed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 76-99
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  • 77
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    Investigation of package sealing using organic adhesives (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A systematic study was performed to evaluate the suitability of adhesives for sealing hybrid packages. Selected adhesives were screened on the basis of their ability to seal gold-plated Kovar butterfly-type packages that retain their seal integrity after individual exposures to increasingly severe temperature-humidity environments. Tests were also run using thermal shock, temperature cycling, mechanical shock and temperature aging. The four best adhesives were determined and further tested in a 60 C/98% RH environment and continuously monitored in regard to moisture content. Results are given, however, none of the tested adhesives passed all the tests.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Proc. of the 1977 NASA(ISHM Microelectronics Conf.; p 77-94
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  • 78
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    The 26-meter S-X Conversion Project (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The 26-meter S-X conversion project provides for the conversion of an existing 26-meter S-band subnet to a 34-meter S- and X-band subnet. The subnet chosen for conversion consists of the following stations: DSS 12 near Barstow, DSS 44 in Australia, and DSS 62 in Spain. The main subsystems effected by this project are the antenna mechanical, antenna microwave, and receiver-exciter. In addition to these, there are many project-related electronic equipments that have been added to the existing station equipment. The major subsystems are essentially through the design stage with the antenna mechanical subsystem completed through detail design with procurement in process.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 157-167
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  • 79
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    Minimum-weight codewords in the (128,64) BCH (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Techniques of combinational algebra and computer simulation are combined to determine the number of weight 22 codewords in the (128,64) BCH code which is being studied for use on future deep-space missions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network p92-94 (SEE N78-24161 15-12)
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  • 80
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    Complex mixer system modifications (1977)
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    Publication Date: 2011-08-17
    Description: Modifications of the complex mixer system to increase bandwidth and number of channels were made. Three modified complex mixers were installed at DSS 14 and were used to process planetary radar signals in March and April of 1977.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 88-91
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  • 81
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    Viking extended mission support (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The period from 1 July through 31 August 1977 is covered and included is the remainder of post DSN Mark 3 Data Subsystem Implementation Project Viking-related testing at DSS14. Also included are reports on the Viking DSN Discrepancy Reporting System, Viking command support, tracking support, and periodic tests conducted with the Viking spacecraft.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 28-33
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  • 82
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    Voyager flight project: DSN Telecommunications Compatibility Test Program (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The Voyager Flight Project - DSN Telecommunications Compatibility Test Program consisted of three phases: Subsystem Design, System Design, and System Verification Tests. Subsystem Design Tests were performed during mid 1976. System Design Tests were performed during late 1976 and early 1977. System Verification Tests were performed during the spring and summer of 1977. This article describes the System Design Tests and test results that provided the basis for establishment of telecommunications design between the DSN and the Voyager Flight Project.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 13-27
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  • 83
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    DSN radio science system description and requirements (1977)
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    Publication Date: 2011-08-17
    Description: The data system created to collect the functions performed by the Deep Space Network in support of spacecraft radio science experiments is described. Some of the major functional requirements presently being considered for the system are delineated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 119-129
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  • 84
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    EMI survey for maritime satellite 1535-1645-MHz shipboard terminal (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A 15,690-ton commercial container ship was selected as lead ship for an onboard electromagnetic-interference (EMI) survey prior to installation of 1535-1645-MHz (L-Band) shipboard terminals for communication via a maritime satellite. In general, the EMI survey revealed tolerable interference levels on board ship. Radiometer measurements indicate antenna-noise temperatures less than 70 K at elevation angles of 5 deg and greater at 1559 MHz at the output terminals of the 1.2-m diameter parabolic-dish antenna for the L-band shipboard terminal. Other EMI measurements include field intensity from 3-cm and 10-cm wavelength pulse radars, and conducted-emission tests of primary power lines to both onboard radars.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-19; Nov. 197
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  • 85
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    Implementation of the radio science subsystem in the DSN (1978)
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    Publication Date: 2011-08-17
    Description: The functional characteristics of a subsystem for support of radio science data acquisition requirements are described. The factors that were of major importance in the design and implementation approach are considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 282-287
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  • 86
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    Power conservation for reflector antennas with truncated feed patterns (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Reflector-antenna calculations using idealised truncated feed patterns can lead to incorrect values of total secondary radiated power. It is demonstrated that this discrepancy is due to the presence of higher-order spherical modes incident on the reflector. When a proper spherical-wave expansion of the incident field is used, in conjunction with the physical-optics technique, to determine the scattered field, the total power of the scattered field will equal the power radiated by the feed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Electronics Letters; 12; Mar. 18
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  • 87
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    Satellite communications at the Goddard Space Flight Center (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Starting with the 1960 Delta launch of the first Echo satellite, NASA's Goddard Space Flight Center (GSFC) became one of the pioneers in satellite communications. Attention is given to the project Syncom, the Applications Technology Satellite (ATS) program, the ATS-6 project, and current GSFC efforts. After the decision announced in January of 1973 that NASA would phase out of communications satellite programs, the communications effort at GSFC concentrates on the operation of ATS spacecraft in orbit, experiments in the 12- to 14 GHz frequency band, and advanced communications research.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Signal; 30; Mar. 197
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  • 88
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    Real-time video compression algorithm for Hadamard transform processing (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A real-time digital video processor using Hadamard transform techniques to reduce video bandwidth is described. The processor can be programmed with different parameters to investigate various algorithms for bandwidth compression. The processor is also adaptive in that it can select different parameter sets to tradeoff spatial resolution for temporal resolution in the regions of the picture that are moving. Algorithms used in programming the system are described along with results achieved at various levels of compression. The algorithms relate to spatial compression, temporal compression, and the adaptive selection of parameter sets.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-18; Feb. 197
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  • 89
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    VLBI (Very Long Baseline Interferometry) instrumental effects, part 1 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Very Long Baseline Interferometry (VLBI) is a method for observation of extragalactic radio sources which appears to have potential for precise long-distance earth surveying, clock synchronization and spacecraft navigation. Many researchers have been working to establish the accuracy of VLBI observations. The intent of the work reported here is to review the principal components of the VLBI instrument in order to estimate and/or bound the systematic error contributions. In this first of a series of articles, the definitions and tools which are needed in order to apply filter transfer-function analysis to the VLBI receiver are established and they are used to estimate the sensitivity of the VLBI receiver to plausible filter variations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 54-80
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  • 90
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    Statistical assessment of speech system performance (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Methods for the normalization of performance tests results of speech recognition systems are presented. Technological accomplishments in speech recognition systems, as well as planned research activities are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 265-284
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  • 91
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    The Army word recognition system (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The application of speech recognition technology in the Army command and control area is presented. The problems associated with this program are described as well as as its relevance in terms of the man/machine interactions, voice inflexions, and the amount of training needed to interact with and utilize the automated system.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 207-215
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  • 92
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    Speech systems research at Texas Instruments (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An assessment of automatic speech processing technology is presented. Fundamental problems in the development and the deployment of automatic speech processing systems are defined and a technology forecast for speech systems is presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 289-299
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  • 93
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    Automatic speech recognition research at NASA-Ames Research Center (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A trainable acoustic pattern recognizer manufactured by Scope Electronics is presented. The voice command system VCS encodes speech by sampling 16 bandpass filters with center frequencies in the range from 200 to 5000 Hz. Variations in speaking rate are compensated for by a compression algorithm that subdivides each utterance into eight subintervals in such a way that the amount of spectral change within each subinterval is the same. The recorded filter values within each subinterval are then reduced to a 15-bit representation, giving a 120-bit encoding for each utterance. The VCS incorporates a simple recognition algorithm that utilizes five training samples of each word in a vocabulary of up to 24 words. The recognition rate of approximately 85 percent correct for untrained speakers and 94 percent correct for trained speakers was not considered adequate for flight systems use. Therefore, the built-in recognition algorithm was disabled, and the VCS was modified to transmit 120-bit encodings to an external computer for recognition.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 143-170
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  • 94
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    Multi-user real time word recognition system (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Technological accomplishments in speech recognition systems are presented. A discrete word recognition system which contains an audio spectrum analyzer is described in detail.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 301-304
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  • 95
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    Practical applications of interactive voice technologies: Some accomplishments and prospects (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A technology assessment of the application of computers and electronics to complex systems is presented. Three existing systems which utilize voice technology (speech recognition and speech generation) are described. Future directions in voice technology are also described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 217-234
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  • 96
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    Automatic speech recognition technology development at ITT Defense Communications Division (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An assessment of the applications of automatic speech recognition to defense communication systems is presented. Future research efforts include investigations into the following areas: (1) dynamic programming; (2) recognition of speech degraded by noise; (3) speaker independent recognition; (4) large vocabulary recognition; (5) word spotting and continuous speech recognition; and (6) isolated word recognition.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 305-316
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  • 97
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    Airborne East Coast/Midwest urban survey at 121.5/243 MHz (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results of an airborne RF interference measurement survey of the emergency-distress, Search and Rescue frequency bands at 121.5 and 243 MHz at an altitude of 25,000 ft over the U.S. East Coast and Midwest urban areas are presented. Included are a series of minutely median profile plots of antenna-noise temperature computed from RF interference power measurements at the output terminal of a quarter-wavelength monopole antenna, for both daytime and nighttime observations. The greatest value, 450,000 K, of minutely median temperature was recorded over New York City at 121.5 MHz during the day. East Coast urban areas exhibited a day-night effect at 121.5 MHz, where nighttime observations had a median value of 8.6-dB below daytime values; Midwest counterparts did not exhibit a significant day-night effect at 121.5 MHz.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-21; May 1979
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  • 98
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    Loaded horizontal antenna over an imperfect ground (1978)
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    Publication Date: 2011-08-17
    Description: The effect of loading for antennas over an imperfect ground is analyzed. The Fresnel reflection coefficient technique is used to derive an E-integral equation for the antenna current. An optimization method is employed to determine the critical loading parameter which enforces a traveling wave current on the antenna. Results are given for the critical loading parameters, antenna currents, input impedances, and radiation patterns for various antenna dimensions and ground parameters. Calculations of the time-domain behavior of the current are presented to show the effect of loading on antenna transient response.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-26; Nov. 197
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  • 99
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    Solving the current element problem over lossy half-space without Sommerfeld integrals (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An approach is presented for efficient computation of the vector potentials arising in the problem of a current element radiating over a lossy half-space. The present approach departs from the conventional ones in that it works primarily with the transform domain representations rather than with the Sommerfeld integrals which are the corresponding spatial domain counterparts. The key step in the present method is to approximate the transforms using a suitable approximation which is valid for a wide range of parameters of practical interest. The approximated transforms can be inverted in a closed form for the horizontal component of the vector potentials and can be expressed in a computationally efficient form for the vertical component. Numerical results illustrating the accuracy of the method are presented and some estimates of comparative computational times are also included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-27; Nov. 197
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  • 100
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    Digital techniques for ULF wave polarization analysis (1979)
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    Publication Date: 2011-08-17
    Description: Digital power spectral and wave polarization analysis are powerful techniques for studying ULF waves in the earth's magnetosphere. Four different techniques for using the spectral matrix to perform such an analysis have been presented in the literature. Three of these techniques are similar in that they require transformation of the spectral matrix to the principal axis system prior to performing the polarization analysis. The differences in the three techniques lie in the manner in which determine this transformation. A comparative study of these three techniques using both simulated and real data has shown them to be approximately equal in quality of performance. The fourth technique does not require transformation of the spectral matrix. Rather, it uses the measured spectral matrix and state vectors for a desired wave type to design a polarization detector function in the frequency domain. The design of various detector functions and their application to both simulated and real data will be presented.
    Keywords: COMMUNICATIONS AND RADAR
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