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The Venus Balloon Project telemetry processing

The peculiarities of the Venus Balloon telemetry system required the development of a new methodology for the telemetry processing, since the capabilities of the Deep Space Network (DSN) telemetry system do not include burst processing of short frames with two different bit rates and first bit acquisition. A software package was produced for the non-real time detection, demodulation, and decoding of the telemetry streams obtained from an open loop recording utilizing the DSN spectrum processing subsystem-radio science (DSP-RS). A general description of the resulting software package (DMO-5539-SP) and its adaptability to the real mission's variations is contained.

Urech, J. M.↗

Venus DSS operations

Venus Deep Space Station experiments involving telemetry with Mariner IV spacecraft in cooperation with Mars Deep Space Station

TELEMETRY↗

Ka-Band High-Rate Telemetry System Upgrade for the NASA Deep Space Network

The NASA Deep Space Network (DSN) has a new requirement to support high-data-rate Category A (Cat A) missions (within 2 million kilometers of Earth) with simultaneous S-band uplink, S-band downlink and Ka-band downlink. The S-band links are required for traditional TT&C (Telemetry, Tracking, and Command) support to the spacecraft, while the Ka-band link is intended for high-data-rate science returns. The new Ka-band system combines the use of proven DSN cryogenic designs, for low system temperature, and high data rate capability using commercial telemetry receivers. The initial Cat A support is required for the James Webb Space Telescope (JWST) in 2013 and possibly other missions. The upgrade has been implemented into 3 different 34-meter Beam Waveguide (BWG) antennas in the DSN, one at each of the complexes in Canberra (Australia), Goldstone (California) and Madrid (Spain). System test data is presented to show that the requirements were met and the DSN is ready for Cat A Ka-band operational support.

space communications↗

Voyager telecommunications - The broadcast from Jupiter

The means by which the data collected by the Voyager 1 mission to Jupiter were returned to earth are presented. Radio links between the earth and the spacecraft are used for the transmission of both imaging and nonimaging telemetry from the spacecraft and commands from the earth and for radiometric observations of the spacecraft and its environment. Features which have lead to vast improvements in the capability of the Voyager telecommunications system over that of previous space probes include the use of X-band rather than S-band telemetry, a dual power X-band traveling wave tube amplifier, a 3.7 m spacecraft antenna and a single channel telemetry system with concatenated coding. Communications equipment at the three ground complexes of the Deep Space Network for telemetry reception includes 64 m steerable antennas, cryogenic maser preamplifiers and a phase-lock loop receiver. Voyager 1 has met or exceeded all of its telecommunications requirements, providing a 98% data return and a total of 2 x 10 to the 11th data bits during the Jupiter encounter.

Edelson, R. E.↗

Tracking the Galileo spacecraft with the DSCC Galileo Telemetry prototype

On day of the year 062, 1994, a prototype of the Deep Space Communications Complex Galileo Telemetry subsystem successfully tracked and processed signals from the Galileo spacecraft, under fully suppressed-carrier modulation. The demonstration took place at Goldstone, employing the 70-m antenna and the 34-m high-efficiency antenna. This article presents the findings from that demonstration. Specific issues are the system performance in terms of signal-to-noise (SNR) degradation and the arraying gain. Validation of the test results is via symbol-error-rate measurement and the standard symbol SNR. The analysis is also extended to include characterization of the signal received from Galileo.

Pham, T. T.↗

Cost and Performance Comparison of an Earth-Orbiting Optical Communication Relay Transceiver and a Ground-Based Optical Receiver Subnet

Optical communications can provide high-data-rate telemetry from deep-space probes with subsystems that have lower mass, consume less power, and are smaller than their radio frequency (RF) counterparts. However, because optical communication is more a.ected by weather than is RF communication, it requires groundstation site diversity to mitigate the adverse e.ects of inclement weather on the link. An optical relay satellite is not a.ected by weather and can provide 24-hour coverage of deep-space probes. Using such a relay satellite for the deep-space link and an 8.4-GHz (X-band) link to a ground station would support high-data-rate links from small deep-space probes with very little link loss due to inclement weather. We have reviewed past JPL-funded work on RF and optical relay satellites, and on proposed clustered and linearly dispersed optical subnets. Cost comparisons show that the life cycle costs of a 7-m optical relay station based on the heritage of the Next Generation Space Telescope is comparable to that of an 8-station subnet of 10- m optical ground stations. This makes the relay link an attractive option vis- a-vis a ground-station network.

Wilson, K. E.↗

A high performance, continuously variable data rate, digitally implemented BPSK modem for deep space network

This paper describes a high performance, digital, BPSK modem designed to improve the telemetry data handling capability of NASA's Deep Space Network. The data rate is continuously variable from 0.5 Mbps to 30 Mbps. It uses newly designed, high speed digital alogrithms for receive filtering, carrier tracking, bit timing and AGC. The carrier and bit time tracking loops have been designed to provide fast acquisition and low tracking phase jitter at E sub b/N sub 0 as low as -4 dB and bit transition density as low as 10%. The performance of the modem is within 0.65 dB below 10 Mbps, 1.0 dB from 10 Mbps to 20 Mbps, and 1.5 dB above 20 Mbps of theoretical coherent BPSK at a BER of 0.0004.

Paik, W. H.↗

The performance of VLA as a telemetry receiver for Voyager planetary encounters

The Very Large Array (VLA) was proposed for use as a supplement to the Deep Space Network (DSN) for telemetry reception at Voyager 2 Uranus and Neptune encounters. The main problem with the use of VLA for telemetry is that it is not capable of producing a continuous stream of data. Gaps of one millisecond follow every 51 milliseconds of data. The effect of these millisecond gaps on coded telemetry is investigated. An upgapped system of the same aperture as the VLA would be capable of handling data rates of 38.4 kbps at Uranus encounter and 19.2 kbps at Neptune encounter. It is shown that VLA with (7, 1/2) convolutional coding (the baseline coding scheme for Voyager) will support a data rate of 10.8 kbps but not 19.2 kbps at both Uranus and Neptune. It is also shown that by implementing Voyager's concatenated Reed-Solomon/convolutional coding capability, data rates of 38.4 kbps and 19.2 kbps would be achievable at Uranus and Neptune respectively. Concatenation also offers a factor of 2 improvement in overall throughput.

Deutsch, L. J.↗

NASA Deep Space Network Operations Scheduling

The functioning of the Deep Space Network Operations Scheduling, Jet Propulsion Laboratory, CA is reviewed. The primary objectives of the Operations Scheduling are: to schedule the worldwide global allocation of ground communications, tracking facilities, and equipment; and to provide deep space telecommunications for command, tracking, telemetry, and control in support of flight mission operations and tests. Elements of the earth set are Deep Space Stations (DSS) which provide the telecommunications link between the earth and spacecraft; NASA Communications Network; Network Data Processing Area; Network Operations Control Area which provides operational direction to the DSS; Mission Control and Computing systems; and Mission Support areas which provide flight control of the spacecraft. Elements of the space set include mission priorities and requirements which determine the spacecraft queue for allocating network resources. Scheduling is discussed in terms of long-range (3 years), mid-range (8 weeks), and short-range (2 weeks).

Enari, D. M.↗