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Telemetry Format. CCSDS Advanced Orbiting System (AOS) standard Data Generation Engineering: Probe Bus (.25 -1 kbps) & Instrument Critical Hsk (.048 kbps) Science data (Science data + Housekeeping data) Variable 1-500 kbps collection rate into DPU Data Types
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Telemetry Format • CCSDS Advanced Orbiting System (AOS) standard • Data Generation • Engineering: Probe Bus (.25 -1 kbps) & Instrument Critical Hsk (.048 kbps) • Science data (Science data + Housekeeping data) • Variable 1-500 kbps collection rate into DPU • Data Types • Virtual channels are used to distinguish between different types of data: • VC0 SC Real-time Engineering • VC1 SC Stored Engineering • VC2 IDPU Burst Science data • VC3 IDPU Slow Survey Data • VC4 IDPU Fast Survey Data • VC5 IDPU Engineering Data • VC63 Fill data
Telemetry Storage • Probe Housekeeping data is continuously stored in Bulk memory • Critical Instrument Housekeeping data is stored into memory along with that acquired by the Probe Bus, even during periods of ground contact • The Probe Housekeeping data storage rate is dependant upon the amount of free space in the Bulk memory array • The Housekeeping data storage rate is reduced by filtering telemetry packets • An adaptive algorithm reduces the storage rate so that filtered telemetry is always stored, up to one orbit plus one day from last contact • Default storage rates and filter table parameters selectable for each Probe • Filter parameters may be changed by ground/stored command • Data Storage Plan • Probe Engineering data VC1 always stored in Probe SSR at programmed rate • IDPU Science Data VC3-VC5 stored in IDPU SSR • Probe Bus Bulk memory provides Bus H/K and Critical Instrument H/K data storage, 2 partitions • Partition 1 is a fixed size First-In First-out buffer for H/K telemetry • Partition 2 contains Probe Bus events generated by Flight Software
Telemetry Downlink • Housekeeping telemetry (VC0) consists of Probe Bus and Critical Instrument data • Housekeeping data is transmitted to the ground at the same rate at which it is acquired during periods of ground contact, Normal Ops • Filtered to 1 kbps during Launch & Contingency operation modes • Filtered to .25 kbps during 4-day orbits, .50 kbps during 2 day orbits • Multiple telemetry rates: 1 –2048 kbps • Playback Plan • Probe Transmitter ON by FOT or ATS Command • Probe Outputs VC0 & Fill • After FOT determines solid link margin, Commands VC1 playback • If VC1 errors, can re-command VC1 playback • FOT commands IDPU to playback. • IDPU Outputs VC2,3,4,5 as prioritized by internal configuration • Probe always mixes VC0 with priority over IDPU data. • Probe Transmitter OFF by FOT or ATS Command or Time Limit
Telemetry Diagram BAU SSR (11 MB) BAU HSK Mgr IDPU HSK Mgr 38 kbps .1 Kbps 50 kbps min IDPU FMTR DMA Comm Card Multiplexor Transmitter 2Mbps 2 Mbps IDPU SSR (256 MB) IDPU FMTR will keep up with 2Mbps data rate. BAU can output at rate (11MB/30 min)= ~50 kbps