[Top] | [Previous] | [Next]

B-4.2 Telemetry Processing

One may further examine the Telemetry Functional Area by decomposing each process in Figure B-2 to their respective subprocesses. To determine processing load, two input streams will be shown on the lower-level diagrams: one SOH stream at 75 bps to 128 Kbps, and one Mission stream at 1.0 to 5.0 Mbps, including embedded SOH data of 128 kbps. Process Telemetry is shown in Figure B-3.

Figure B-3. Process Telemetry data flow diagram.

The telemetry IB provides all processing parameters for each of the following subprocesses:

Sync/Extract Telemetry - This function ingests the serial PCM streams; performs bit/frame synchronization, decommutation, format switching, and embedded stream extraction; archives and recalls time-tagged mainframes; and produces raw measurands. Archiving/recall is accomplished at the PCM rate, and raw measurands are output at 3 times the PCM rate due to the additional tag.

Convert Measurands - This function forms derived measurands, applies algorithms (including telemetry limit checking and alarm generation), and assesses data quality. Data and alarm outputs are provided to Display SV Health & Status, primarily for a telemetry analyst who is monitoring the satellite in parallel with the mission controller.

Monitor Telemetry - In this function telemetry data is compared to conditions provided in the telemetry knowledge base related to anomaly detection and any commanded state changes. It determines the current SV state and provides anomaly messages as required to the mission controller.

Display SV Health and Status - This process provides visual display to the operator indicating SV health and status and allows the operator to select display formats