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Flight Software Design for PH Data Sampling and Compression

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Explore the design of data formatting, compression formats, PH event packets, and particle sampling in-flight software. Learn about rates, event formats, and packet types for efficient PH data processing. Discover the algorithm for rate compression and PH event structures.

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Flight Software Design for PH Data Sampling and Compression

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  1. Flight Software Design STEREO/HETData Formatting/PH Sampling Donald Reames DVR

  2. Rates and Sampled Particle PHs Wind/EPACT flight data DVR

  3. Science Data Formatting • Rate and PH compression formats • Rate packets – 16-bit compressed HW and SW rates • PH event packets – compressed PH events • H1-only particles • Stopping particle • Penetrating particles • PH stimulator events • Table, beacon, and housekeeping packets • PH sampling and queues and packet sampling DVR

  4. Algorithm for RateCompression (24 bit->16 bit) • /* 32-bit -> 16-bit compression for SW and HW rates */ • /* usage: rateout=pack_rate(ratein); */ • unsigned int pack_rate(int ratein) • { • unsigned int rateout, power=0; • while (ratein&0xfffff000) • { • power+=0x0800; • ratein>>=1; • } • rateout=ratein; • if (power) • rateout=power+0x0800|((rateout&0x07ff)); • return rateout; • } DVR

  5. HET PH Event Formats • PH events (except H1 singles) consist of a 16-bit header followed by the appropriate number of 16-bit packed pulse heights. The bit pattern of the 16-bit header is as follows (listed in lsb to msb order): • 3-bits Count of PHs in this event • 8-bits Onboard SW bin this event was assigned to • 1-bit Stimulator event flag • 1-bit Current rate mode of the HET • 3-bits PH category • Each individual PH is compressed from the 24-bit value read from the ASIC to a 16-bit value with the following bit pattern (lsb to msb) • 11-bits PH value • 1-bit Overflow bit • 1-bit High/low gain • 3-bit PH number (H1i, H1o, H2, …H6) DVR

  6. ‘A’ or Rates Packets DVR

  7. ‘B’ or Status and Single PH Packet DVR

  8. ‘C’ or Stopping-Particle PH Packets DVR

  9. ‘D’ or Penetrating-Particle PH Packet DVR

  10. ‘E’ or Table Listing Packet DVR

  11. ‘F’ or Beacon Packets DVR

  12. ‘G’ or Housekeeping Packets DVR

  13. Sampling PH Events for Readout • Nominal output packets: 1-A, 1-B, 3-C, 1-D (+1F & 1G) • Stopping particles are queued as to H, He, and heavies • Each species is allocated 1/3 of the telemetry space • Any empty heavies space is filled with He • Any remaining empty space is filled with H • Empty C packets (after 1) are reassigned as D packets • Penetrating particles are treated analogously • E packets normally are dribbled out at about 1 every 16 frames, but empty D packets are reassigned as E packets. DVR

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