• Interagency Arraying

      Cox, Henry G.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      Voyager ground aperture requirements for Neptune encounter in August 1989 exceed the expected capabilities of the Jet Propulsion Laboratory's Deep Space Network (DSN) 70- and 34-meter antennas. Agreements have been consummated with the National Science Foundation to array the National Radio Astronomy Observatory's Very Large Array in New Mexico and with the Commonwealth Scientific and Industrial Research Organization's Parkes Radio Telescope in Australia with the DSN. This technique, which was demonstrated during Voyager's Uranus encounter, will provide a greater return of imaging and non-imaging science data. The arrays consist of the normal facility receiving equipment at each location, augmented by special receiving, combining, recording, and monitor and control equipment. This equipment has been designed, is being implemented, and will be operated during the Neptune encounter to effectively double the available antenna aperture over the western United States and Australia.
    • Voyager Image Data Compression and Block Encoding

      Urban, Michael G.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      Telemetry enhancement techniques implemented through flight software modifications and utilization of special flight hardware enable the Voyager 2 spacecraft to reduce telemetry transmission rates used at Saturn by over 50% for the extended mission to Uranus and Neptune with negligible loss in information return. Techniques employed include: * Parallel operation of the redundant Flight Data Subsystem (FDS) processors * Image Data Compressor (IDC) using noiseless (fully reconstructable) coding techniques * Reed-Solomon (RS) encoding of downlink telemetry.
    • Voyager Neptune Telemetry: The Voyager Telemetry System

      Madsen, Boyd D.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      Improvements to the Voyager telemetry system, which have been implemented on the spacecraft and in the Deep Space Network (DSN), will allow a net science data return from Neptune essentially equivalent to that received from Saturn in spite of the increased range. Enhancements to the system performance include: Increased DSN ground station G/T, Inter-agency arraying, Spacecraft data compression, Reed-Solomon concatenated coding, Reduced telemetry link uncertainties. Net improvements totaled 8 dB in a system that was state-of-the-art when Voyager was launched in 1979.
    • Voyager-Neptune Telemetry: The DSN 70 Meter Antenna Upgrade

      Hall, Justin R.; McClure, Donald H.; California Institute Technology (International Foundation for Telemetering, 1987-10)
      The Deep Space Network is responsible for the acquisition of in-situ science and engineering measurements and navigation data from spacecraft whose missions are to explore the Solar System. It must respond to new opportunities in the mission set supported so as to maintain or enhance mission science value. The large capital investment in such a Network mandates an evolutionary design approach wherein upgrades can be effected at low cost, and if appropriate, on existing capability. The 64-Meter antenna design, completed in 1963, is an example of this approach, in that it has permitted a relatively low-cost upgrade which increases performance significantly. The technology assessment was completed in 1975, and the option was exercised in 1986, when needed. Several key characteristics of the DSN design approach, the costs to upgrade performance over the past several decades, and some fundamental constraints on performance are discussed. Finally, the specific 70-Meter upgrade task and resulting overall benefits to Voyager-Neptune and the mission set are summarized.