SMM

Telecommunications Description

The SMM experiments generated telemetry data at the following rates: HXIS: 5.250 kbps (70%), XRP: 1.750 kbps (70%), C/P: 0.125 kbps (100%), GRE: 0.750 kbps (70%), ACRIM: 0.125 kbps (70%), HXRBS: 1.625 kbps (70%), and UVSP: 1.375 kbps (80%).

The utilization percent (%) indicates periods during each orbit when either science data or housekeeping data is being collected. Two tape recorders with 4.5E8 bit capacity were on SMM to serve all instruments. A third tape recorder was provided for the C/P experiment. Each tape recorder stored data at 16 kbps, so each recorder could hold approximately four orbits worth of data. Of this, 11 kbps of data were devoted to science data (broken down in the table above). Until the C/P tape recorder failed, the total data collection rate was 32 kbps. SMM used NASA ground stations for most telemetry returned, but occasional TDRSS contacts carried some data. All data were recorded on board andand returned via recorder playback when a ground station or TDRSS contact was available.