• 117.6 Kilobit Telemetry from Mercury-A Major Deep Space Telecommunication Advance

      Clarke, Victor C.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      For nearly eight hours on March 29, 1974, Mariner 10 transmitted imaging telemetry in real time at 117.6 Kbps from Mercury. During this time, 562 very high quality frames were received, even though the bit error rate was only about 1 in 40. The transmission of 117.6 Kbps from Mercury is a magnificent telecommunications achievement, which permitted an order of magnitude increase in imaging science data return. The Mariner 10 imaging scientists' requirements, simply stated, were to obtain maximum area coverage at highest spatial resolution. More precisely, they desired photomosaics which were equivalent to the best earth-based pictures on the Moon, i.e., about 1 km resolution. The purpose of this paper is principally to relate the methods by which these "desirements" were translated into measurable telecommunication system requirements and some of the attendant tradeoffs. Additionally, same of the steps taken to achieve their goal are recited.
    • 117.6-Kilobit Telemetry from Mercury In-Flight System Analysis

      Evanchuk, V. L.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      This paper discusses very specifically the mode of the Mariner Venus/ Mercury 1973 (MVM'73) telecommunications system in the interplexed dual channel 117.6 kilobits per second (kbps) and 2.45 kbps telemetry. This mode, originally designed for only Venus encounter, was also used at Mercury despite significantly less performance margin. Detailed analysis and careful measurement of system performance before and during flight operations allowed critical operational decisions, which made maximum use of the system capabilities.
    • Design of the Mariner Jupiter/Saturn 1977 Telemetry System

      Wood, Gordon E.; Risa, Thomas; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      In 1977 NASA will launch two spacecraft to perform scientific investigations of the Jupiter and Saturn planetary systems. The science payload includes a total of 10 instruments to support both the interplanetary cruise and planetary encounter phases. These will be the first launches of a new generation of Mariner-class spacecraft designed for outer-planet missions. The telemetry system design for these missions was especially challenging because of extreme communication ranges (1.5 X 10⁹ km), high data rate requirements (up to 115.2 kb/s), and more stringent data quality requirements than previous Mariner missions. This paper discusses the evolution and design of the Mariner Jupiter/Saturn 1977 telemetry system and presents the performance anticipated therefrom.
    • The Impact of Robots on Planetary Mission Operations

      Hooke, A. A.; Larman, B. T.; Whitney, W. M.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      For reasons of efficiency and safety, unmanned roving vehicles sent to explore remote planetary surfaces must carry out some of their tasks without step-by-step human control. To realize the benefits that such semiautonomous machines can provide will require some changes in how planetary missions axe presently planned and conducted. Specifically, mission profiles will have to be based on tasks or functions rather than sequences of timed events, scientists will have to be more directly involved in the control of their instruments, and present ideas concerning spacecraft safety, testing and simulation of vehicle performance, telemetry design, and ground-system implementation must be reexamined.
    • Martian and Lunar Science with Remotely-Controlled Long-Range Surface Vehicles

      Jaffe, Leonard D.; Choate, Raoul; California Institute of Technology; TRW Systems Group (International Foundation for Telemetering, 1974-10)
      Science objectives are outlined for long surface traverse missions on Mars and the moon, with remotely-controlled roving vehicles. Series of candidate rover science payloads are proposed, varying in purpose, development needed, cost, and weight (35 to almost 300 kg). A high degree of internal control will be needed on the Mars rover, including the ability to carry out complex science sequences. Decision-making by humans in the Mars mission includes supervisory control of rover operations and selection of features and samples of geological and biological interest. For the lunar mission, less control on the rover and more on earth is appropriate. Operational problem areas for Mars include control, communications, data storage, night operations, and the mission operations system. For the moon, science data storage on the rover would be unnecessary and control much simpler.
    • Performance of Noncoherent MFSK Channels with Coding

      Butman, S. A.; Lyon, R. F.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      Computer simulation of data transmission over a noncoherent channel with predetection signal-to-noise ratio ST/N₀ = 1 shows that convolutional coding can reduce the energy requirement by 4.5 dB at a bit error rate of 0.001. The effects of receiver quantization and choice of number of tones are analyzed; nearly optimum performance is attained with eight quantization levels and sixteen tones at ST/N₀ = 1. The effects of changing ST/N₀ are also analyzed; for lower ST/N₀, accurate extrapolations can be made from the data, but for higher ST/N₀ the results are more complicated. These analyses will be useful in designing telemetry systems when coherence is limited by turbulence in the signal propagation medium or oscillator instability.
    • Time Response Simulation of the 1975 Viking Orbiter Digital Tape Recorder

      Mukhopadhyay, Asok K.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      The objective of this study is to verify and understand in depth the performance of the speed control (frequency loop) servo of the 1975 Viking Orbiter (VO75) digital tape recorder (DTR). The linear frequency-domain methods, such as the Bode Plot and the Root Locus, are inadequate in analyzing the VO75 DTR servo due to such dominant non-linear effects as servo signal limiting and static/dynamic Coulomb friction. The Time Response method employed in this study is written in the Continuous System Simulation Language (CSSL) for the Univac 1108 computer system. In order to demonstrate the power and flexibility of the graphic interactive simulation program, four aspects of system dynamics are interactively adjusted to arrive at a number of stable system configurations which has significantly different tape transport and/or summing amplifier gain, larger static/dynamic Coulomb friction, system lag than envisioned in the nominal design by linear methods.