• The Mars Penetrator Telemetry and Control System

      Bentley, R. D.; Campbell, A. B.; Sandia Laboratories (International Foundation for Telemetering, 1975-10)
      A new method for exploring the planet Mars has been proposed* that will use ground-penetrating vehicles to carry scientific instruments below the Martian surface. The subsurface performance of various sequences of complicated experiments poses challenges in the design of the telemetry and control links. This article describes the overall mission, the penetrator, the constraints imposed by the mission and the penetrator, and a design for the telemetry/control system. This design uses a microprogrammed microprocessor; the sequences of commands are stored in a Read-Only-Memory (ROM), and a particular sequence is initiated by transmitting from the Earth the address in the ROM that contains the first of the commands for the specific sequence to be performed. Data from the experiments are stored in a memory for later transmission to an orbiter that serves as a relay station for the command and data links with Earth.
    • A Telemetry Link for an Earth Penetrator

      Caffey, Thurlow W. H.; Sandia Laboratories (International Foundation for Telemetering, 1975-10)
      The design and field-testing of a telemetry link to send signals to the surface of the earth from an earth penetrator are described. The link uses a PCM/FM format at a frequency of 10.5 kHz, dissipates 8 watts, and fits within a cylinder with an inside diameter of 100 mm. A bit error rate of less than 10⁻⁵ was achieved from a depth of 52 meters at a bit rate of 10³ bits per second.