STEREO IMPACT HETSIT Software Requirements and Design Review

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 Flight Software Design STEREO/HET Data Formatting/PH Sampling Donald Reames DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 Rates and Sampled Particle PHs Wind/EPACT flight data DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 Science Data Formatting • Rate and PH compression formats • Rate packets – 16 -bit compressed HW and SW rates • PH event packets – compressed PH events – – H 1 -only particles Stopping particle Penetrating particles PH stimulator events • Table, beacon, and housekeeping packets • PH sampling and queues and packet sampling DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 Algorithm for Rate Compression (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&0 xfffff 000) { power+=0 x 0800; ratein>>=1; } rateout=ratein; if (power) rateout=power+0 x 0800|((rateout&0 x 07 ff)); return rateout; } */ DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 HET PH Event Formats • PH events (except H 1 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 (H 1 i, H 1 o, H 2, …H 6) DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘A’ or Rates Packets DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘B’ or Status and Single PH Packet DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘C’ or Stopping-Particle PH Packets DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘D’ or Penetrating-Particle PH Packet DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘E’ or Table Listing Packet DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘F’ or Beacon Packets DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 ‘G’ or Housekeeping Packets DVR

STEREO IMPACT HET/SIT Software Requirements and Design Review, 22 August 2002 Sampling PH Events for Readout • Nominal output packets: 1 -A, 1 -B, 3 -C, 1 -D (+1 F & 1 G) • 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