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NASA NTRS1983

The Telecommunications and Data Acquisition Report

This publication reports on developments in programs managed by JPL's office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground based radio astronomy, it reports on activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, in supporting research and technology, in implementation and in operations. In geodynamics, the publication reports on the application of radio interferometry at microwave frequencies for geodynamic measurements. This publication also reports on implementation and operations for searching the microwave spectrum.

Posner, E. C.↗
NASA NTRS1983

Symbol Stream Combining Versus Baseband Combining for Telemetry Arraying

The objectives of this article are to investigate and analyze the problem of combining symbol streams from many Deep Space Network stations to enhance bit signal-to-noise ratio and to compare the performance of this combining technique with baseband combining. Symbol stream combining (SSC) has some advantages and some disadvantages over baseband combining (BBC). The SSC suffers almost no loss in combining the digital data and no loss due to the transmission of the digital data by microwave links between the stations. The BBC suffers 0.2 dB loss due to alignment and combining the IF signals and 0.2 dB loss due to transmission of signals by microwave links. On the other hand, the losses in the subcarrier demodulation assembly (SDA) and in the symbol synchronization assembly (SSA) for SSC are more than the losses in the SDA and SSA for BBC. It is shown that SSC outperforms BBC by about 0.35 dB (in terms of the required bit energy-to-noise spectral density for a bit error rate of 1,000) for an array of three DSN antennas, namely 64 m, 34m(T/R) and 34m(R).

Divsalar, D.↗
NASA NTRS1983

Radio Astronomy

Deep Space Network (DSN) 26- and 64-meter antenna stations were utilized in support of Radio Astronomy Experiment Selection Panel experiments. Within a time span of 10 days, in May 1983 (267.75 hours total), nine RAES experiments were supported. Most of these experiments involved multifacility interferometry using Mark 3 data recording terminals and as many as six non-DSN observatories. Investigations of black holes, quasars, galaxies, and radio sources are discussed.

Wolken, P. R.↗
NASA NTRS1983

Gain Stability Measurements at S-band and X-band

The Search for Extraterrestrial Intelligence (SETI) requires low noise broadband total power radiometers of high gain stability. Preliminary results of SETI field tests for a variety of receiver configurations at Deep Space Station 13 are discussed. The power spectra of Deep Space Network low noise receiving systems exhibit I/F noise whose spectral index is significantly smaller than unity. The gain stability of the S-band systems tested is almost 0.0001. An appendix presents a derivation of the power spectrum of the output of a square law detector.

Gulkis, S.↗
NASA NTRS1983

A Southern Hemisphere VLBI Survey on a 275-km Baseline

A very long base interferometry (VLBI) survey at 2.29 GHz was conducted using a 275 km baseline consisting of the NASA Deep Space Network tracking site in Tidbinbilla, Australia, and the 64 m antenna located at Parkes, Australia. The purpose of the survey was to identify sources in the southern sky possessing strong compact cores ( 0.1 arcseconds). Such sources will be used to form a reference frame for conducting VLBI geodesy experiments in the Southern Hemisphere. The 70 candidate sources were chosen to be south of -39 degrees declination, and only four had been previously observed from the northern hemisphere. Of the observed sources, 49 were found to have compact structure. In addition to determining correlated flux densities, the delay and delay rate observables of several detected sources were used to determine an estimate of the three dimensional location of the Parkes antenna relative to the Tidbinbilla site with a 1-sigma accuracy of 10 meters.

Morabito, D. D.↗
NASA NTRS1983

Antennas

Reception of the exceedingly small signals from spacecraft typical of deep space communication requires antennas of enormous size, complexity, and precision. The two Voyager spacecraft each have 20-watt X-band transmitters; and at their Saturn encounter distances from Earth of approximately 1.5 billion kilometers, the power density received on the Earth was less than 10 to the minus 19th power watts per square meters. The thrust in deep-space communications improvement was in the areas of ground and spacecraft antenna size and performance increases, spacecraft transmitter power increase, ground receiving system design, and telemetry information coding. Ground antenna theory, design, and performance as related to the particular problem of receiving spacecraft signals using the Deep Space Network (DSN) is described.

Slobin, S. D.↗
NASA NTRS1981

Performance evaluation of antenna arrays with noisy carrier reference

The performance evaluation of coherent receivers with noisy carrier references and multiple antennas is presented. The received signal is assumed to be residual carrier BPSK, with a PLL used for extracting the carrier. Explicit relationships between the error probabilities and the various system parameters are given. Specific results are given for the performance gain of combined carrier referencing over baseband only combining when the channel alignment process is ideal. A simple asymptotic expression for the performance gain is determined when the number of antennas used is increased without bound. Examples using Deep Space Network receivers illustrate the performance of each arraying structure.

Yan, T. Y.↗
NASA NTRS1982

A common-aperture X- and S-band four-function feedcone

Williams and Withington (1979) have considered a prototype X-S-band feedhorn which enabled simultaneous X- and S-band reception from a Cassegrain antenna. This feedhorn has quite successfully demonstrated an alternate method to the standard Deep Space Network (DSN) system of multiple subreflectors and dichroic plate for dual-band reception. In connection with a Network Consolidation Program, involving centralized control of existing antennas and construction of new reflector antennas, a second-generation feedhorn/combiner was conceived to show that this common-aperture feedhorn system was capable of performing all necessary functions the DSN would be called upon to perform with existing and future X-S-band spacecraft. Attention is given to the feedhorn concept, the combiner concept, the first and the second generation of the horn, Sand X-band tuning, and planned capabilities. The feedhorn greatly extends the state of the art in DSN performance and will enhance DSN capabilities in the future.

Withington, J. R.↗
NASA NTRS1983

JPL pulsar timing observations. II - Geocentric arrival times

Monitoring of the behavior of naturally pulsating galactic radio sources, or pulsars, through regularly spaced measurements of pulse arrival times, has been conducted by several laboratories. A tabular presentation is here made of pulse arrival time measurements from the NASA Deep Space Network between late 1968 and early 1981. By expressing the measurements in ephemeris time, and referring them to the geocenter, usable tables of results have been generated for each pulsar listed in the first of the tables given. The considerations addressed by the tables are: (1) a necessary step in the study of pulsar dynamics is the reduction of topocentric arrival times to the barycenter of the solar system; (2) the tabulated data are accessible to all opinions as to the procedures to be used in interpreting arrival time data; and (3) different observing programs can usually be combined to produce an improvement in the total data set.

Downs, G. S.↗
NASA NTRS1983

Internationally supported data acquisition for solar system exploration in the 1990's

Procedures that could be followed for cooperative agreements between countries with large ground station antennas to help provide mission telemetry support for increasing solar system exploration are outlined. It is noted that mission cost reductions, and thereby greater chances that missions will be approved, are offered by the opportunity to make planetary probes multinational efforts. The Canberra station is a suitable site for the Japanese Planet A Halley's comet intercept probe. The French have requested U.S. cooperation in developing VLBI stations in the L-band to receive signals from the Venus balloons and landers being sent as part of a joint French-Soviet mission to Venus and Halley's comet. The construction of the stations would extend the capabilities already present with NASA's deep space network, particularly for tracking the Voyager visits to Uranus and Neptune.

Reid, M. S.↗
NASA NTRS1983

Telecommunications and data acquisition systems support for Voyager missions to Jupiter and Saturn, 1972-1981, prelaunch through Saturn encounter

The Deep Space Network has supported the Voyager Project for approximately nine years, during which time implementation, testing, and operational support was provided. Four years of this time involved testing prior to launch; the final five years included network operations support and additional network implementation. Intensive and critical support intervals included launch and four planetary encounters. The telecommunications and data acquisition support for the Voyager Missions to Jupiter and Saturn are summarized.

Traxler, M. R.↗
NASA NTRS1983

The Telecommunications and Data Acquisition Report

Developments in programs in telecommunication and data acquisition in space communications, radio navigation, radio science, and ground based radio astronomy are reported. Activities of the deep space network (DSN) and its associated ground communication facility (GCF) in planning, supporting research and technology, implementation, and in operations are outlined. The publication of reports on the application of radio interferometry at microwave frequencies for geodynamic measurements are presented. Implementation and operation for searching the microwave spectrum is reported.

Posner, E. C.↗
NASA NTRS1983

Orbit determination of highly elliptical Earth orbiters using VLBI and delta VLBI measurements

The feasibility of using very long baseline interferometric (VLBI) data acquired by the deep space network to navigate highly elliptical Earth orbiting satellites was shown. The navigation accuracy improvements achievable with VLBI and delta VLBI data types are determined for comparison with the Doppler capability. The sensitivity of the VLBI navigation accuracy to the baseline orientation relative to the orbit plane and the effects of major error sources such as gravitational harmonics and atmospheric are examined. It is found that VLBI measurements perform as well as strategies using conventional Doppler, while substantially reducing the required antenna support.

Frauenholz, R. B.↗
NASA NTRS1983

JPL Closeup

Voyager, Infrared Astronomical Satellite, Galileo, Viking, Solar Mesosphere Explorer, Wide-field/Planetary Camera, Venus Mapper, International Solar Polar Mission - Solar Interplanetary Satellite, Extreme Ultraviolet Explores, Starprobe, International Halley Watch, Marine Mark II, Samex, Shuttle Imaging Radar-A, Deep Space Network, Biomedical Technology, Ocean Studies and Robotics are summarized.

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NASA NTRS1984

The Telecommunications and Data Acquisition Report

Developments in space communications, radio navigation, radio science, ground-base radio astronomy, reports on the Deep Space Network (DSN) and its Ground Communications Facility (GCF), and applications of radio interferometry at microwave frequencies are discussed.

Posner, E. C.↗
NASA NTRS1984

Loop Gain and Circuit Parameters for Residual Carrier Tracking in the Advanced DSN Block V Receiver

A circuit level analysis for residual carrier tracking of a deep space network signal by a proposed Block V receiver as conceived by the Receiver Advanced Development Team is presented. The objective is to aid the circuit designer in selection of loop parameters to achieve the required performance objectives. The topics specifically addressed are: (1) loop stability and gain requirements, (2) loop component parametric equations, and (3) phase detector technology.

Young, P. H.↗
NASA NTRS1983

Publications of the Jet Propulsion Laboratory 1982

A bibliography of articles concerning topics on the deep space network, data acquisition, telecommunication, and related aerospace studies is presented. A sample of the diverse subjects include, solar energy remote sensing, computer science, Earth resources, astronomy, and satellite communication.

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