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NASA Space Science Data Coordinated Archive Header


NSSDCA ID: 1990-090B

Telecommunications Description

The telemetry system operates in the X-band (8 GHz). The uplink telecommunication system works in S-band, with a low-power S-band (2 GHz) transmitter for dual-frequency radio-science investigations and early orbit maneuvers. Throughout the mission the spacecraft is tracked by the 34 and 70 m antennas of NASA's Deep Space Network for an 8 hour period each day. For downlink bit rates of 1024 bps and over, real-time data are interleaved with playback of the on-board storage, which holds up to 22 hours of data at 512 bps (and correspondingly more at 256 or 128 bps). Commonly, for a downlink rate of 2048 bps, 8 hours of real-time data sampled at 1024 bps are interleaved with 16 hours of stored data sampled at 512 bps and played back at 1024 bps. Possible combinations of downlink bit rate/real-time bit rate are: 1024/512, 2048/512, 2048/1024, 4096/1024, and 8192/1024 bps; 1024 bps can be all real-time; 512, 256 and 128 bps downlink rates can be all real-time or all playback. Data coverage has been averaging 95%.

Telemetry Path

Telemetry support via Deep Space Network (DSN)

Effective Telemetry

650.0 kbps

Telemetry Rates

0.128-8.192 kbps

Additional Information

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