Jul 03 2009
Communicate, Communicate, Communicate
Communicate – communicate – communicate! That is the subject of our posting this week as we look at another vital component section within the Instrument Unit. This communication system is not what is used by the astronauts for voice and video feeds, rather this is the system used by the spacecraft and its many systems.
The Instrument Unit was in constant communication to the command and control centers. Telemetry data was continuously transmitted that reported to the controllers all of the activity taking place within the complex systems of the Saturn V rocket. The tracking system transmitted vehicle coordinates and angles to the Mission Ground Station and the radio command system was used by the Mission Ground Station to send commands to the various instruments and systems in the spacecraft.
Over 200 parameters were continuously updated by the communications system and sent to the ground, such items included vehicle speed, angle velocity, temperatures, flow rates, pressures, voltage readings, and sensor signals. This data was used to verify that commands were performed as well as to monitor for any potential issues. Data was also maintained for post-flight analysis.
The communication and telemetry systems operated on 28 sub carrier frequencies in the FM band. C-band transponders provided the telemetry and were single pulse and were in the 5.4 to 5.9 GHZ frequency range. 210.8 MHZ was the frequency that carried the radio digital data transmissions that carried all of the system commands. Commands were issued from Mission Control in Houston, TX and then were dispersed through the NASA ground network to be transmitted from the appropriate Earth station that was within the range of the spacecraft.
Antenna arrays included one single directional for transmit and receive and two omni-directionals for transmit and receive. This entire communications system consumed an enormous amount of power and it was powered by four silver-zinc batteries at 28volts each with power supplies to convert the power to 56 volts for the multiple systems.
