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FIELDS Time Domain Sampler Peer Review

FIELDS Time Domain Sampler Peer Review. Keith Goetz University of Minnesota Goetz@umn.edu. STEREO snapshot. STEREO snapshots. STEREO snapshot. Heritage. Time Domain Sampler (TDS) is based on previous instruments Based most recently on STEREO instrument Gathers impulsive events

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FIELDS Time Domain Sampler Peer Review

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  1. FIELDSTime Domain SamplerPeer Review Keith Goetz University of Minnesota Goetz@umn.edu

  2. STEREO snapshot

  3. STEREO snapshots

  4. STEREO snapshot

  5. Heritage • Time Domain Sampler (TDS) is based on previous instruments • Based most recently on STEREO instrument • Gathers impulsive events • Centered peaks • Simultaneous sampling on all channels • Smooth activity - new • Fixed sampling rate – 1.92MSa/s • Programmable effective sampling rate • Programmable event duration • Events have peaks • After that, flight software rates event based on programmable criteria • Quality can be adjusted – up or down - after the fact • When telemetry is available (nominally to DCB), best event is sent • When memory is needed (for a new event), worst event is deleted • Event selection can be based on quality or not – honesty • Low rate stream gives peak activity as a function of time

  6. Analog Inputs • Channel 1 (ADCs want 0V to 2V at <=1MHz) • V1MF • EPARMF • Channel 2 • V2MF • V3-4MF • Channel 3 • V3MF • V1-2 MF • Channel 4 • V4 MF • B MF • SWEAP counts • ? • Unused • V5MF • V1REF, V2REF, V3REF, V4REF, V5REF • V1-2REF, V3-4REF, EPARDC • V1DUST, V2DUST, V3DUST, V4DUST, V5DUST

  7. Big Dust

  8. Dust

  9. FIELDS/TDS Evolution FIELDS was proposed as a single string instrument Within FIELDS, TDS was proposed as a single science board

  10. TDS Evolution In early 2013, Project recognized that FIELDS was central to meeting threshold science – occupying 4 of 9 blocks

  11. TDS Evolution – System-6 • FIELDS then suggested a number of alternatives • increasing reliability • Eventually, we settled on System-6

  12. Configuration

  13. Configuration at UMN

  14. TDS Requirements • TDS-01Mission Length • TDS Components must be selected to withstand the environment of SPP for the duration of the mission. • TDS-02Spacecraft Interface Compliance (General) • TDS shall implement the spacecraft interface protocol… • TDS-03Timing from S/C • TDS shall provide latching facility upon detection of the "Virtual 1PPS" S/C timing signal… • TDS-04 • Timing from DCBTDS shall provide an electrical interface to the Data Control Board capable of…

  15. SWEAP Requirements • TDS-05 SWEAP Interface - CDI • TDS shall provide an electrical interface to the SWEAP instrument capable of sending CDI commands, receiving CDI messages: • [a] sending Command/Data Interface (CDI) messages to SWEAP; • [b] receiving SWEAP status and burst information from SWEAP; • [c] sending TDS time-keeping information; • [d] sending TDS clock synchronization. • TDS-06 SWEAP Interface – Particles • TDS shall provide an electrical interface to the SWEAP instrument capable of: • [a] receiving particle count information from SWEAP • [b] receiving particle synchronization and state information from SWEAP

  16. MAG Requirements • TDS-07 MAG Interface – CDI • TDS shall provide an electrical interface to the MAG Electronics capable of: • [a] setting control registers • [b] receiving MAG Science and Engineering data • [c] provide MAG AC heater synchronization

  17. AEB Requirements • TDS-08 Antenna Electronics Board Interface (AEB) • TDS shall provide an electrical interface to the Antenna Electronics Board capable of: • [a] setting Biasing D/A converters and relays • [b] reading back the biasing voltages • [c] provide DC-DC converter synchronization

  18. LNPS Requirements • TDS-09Low Noise Power Supply Interface (LNPS) • TDS shall provide an electrical interface to the Low Noise Power Supply capable of • [a] setting control registers for Power Control and Housekeeping Channel • [b] receiving an analog housekeeping signal • [c] provide DC-DC synchronization

  19. TDS Requirements • TDS-10 Time Domain Sampler Control • TDS shall provide electrical interfaces to the Time Domain Sampler data acquisition system capable of: • [a] setting TDS instrument modes • [b] receiving TDS instrument data • TDS-11 TDS Memory Management • TDS shall include memory such that: • [a] is capable of storing ~20 TDS snapshot events • [b] allows best available event to be sent to telemetry • TDS-12 TDS Instrument Calibration • TDS analog science and analog housekeeping conversion coefficients are determined and provided prior to S/C Integration to include gain, phase and timing

  20. Science Requirements • TDS-13 E Signals • TDS shall provide an electrical interface capable of: • [a] signal processing and measurement of the low frequency component of E-Field signals • TDS-14 E Signals • TDS shall provide an electrical interface capable of: • [a] signal processing and measurement of the AC or plasma frequency (ranging to ~1MHz) component of E-Field signals." • TDS-15 B Signals • TDS shall provide an electrical interface capable of: • [a] signal processing and measurement of the AC or plasma frequency (ranging to ~1MHz) component of B-Field signals (single axis)." • TDS-16 Instrument Calibration • TDS shall provide calibration parameters and algorithms so as to allow conversion from telemetry units to physical units (gain and offset per channel) prior to S/C Integration.

  21. TDS Block Diagram

  22. TDS FPGA Block - New

  23. Spacecraft picture

  24. FIELDS block diagram

  25. BB2

  26. TDS – Single Board Data Acquisition System • Centers on RTAX4000 FPGA daughter board • Holds all logic, interfaces and LEON 3 processor instantiation • TDS event data gathered by 16-bit ADCs at ~2MSa/s • Multiplexed 16-bit data bus • Simultaneous acquisition of SWEAP particle counts • TDS event data stored directly into dedicated event memory • 16MB event SRAM – 8 parts – 512k by 32bits • Circular buffers • Processor support • 8-bit data bus • Local SRAM w/ ECC • Local boot PROM (some in FPGA?) • Local program EEPROM • S/C serial interfaces • CDI interfaces to DCB, MAG, SWEAP • Device interfaces – AEB, LNPS • Mezzanine interface • Diagnostic UARTs

  27. Issues • Design is advanced • Based on earlier implementation • More than usual at this point (PDR) • Selected ADC is great – but plastic • A cousin was used on STEREO • Putative parts have been obtained (x100) • Lead has been added • DPA has been completed (x5) well • Radiation and Beam • Up-screening • Backup solutions could be painful in performance and power • Overall power • We’re only now getting to good power estimates • Descope alternatives exist • LVDS protection solution is still open

  28. Next • Continue development work with BB2 • FPGA • FSW • Spacecraft Emulator • FIGs for DCB, MAG and SWEAP • Ground software • Modify existing schematic for ETU • Layout ETU

  29. FIELDS-SWEAP Communication

  30. Waveform Zoomed CLK ~2MHz Samples Δt = 500ns V(t) Δt = 500ns count(t)

  31. Waveform Zoomed! Samples Δt = 500ns t = 1,500ns t = 2,000ns t = 2,500ns t = 3,000ns t = 3,500ns t = 4,000ns t = 4,500ns t = 5,000ns V(t) Δt = 500ns V = 0mV V = -2mV V = -4mV V = +5mV V = -12mV V = -15mV V = -10mV V = -5mV count(t) n = 2 n = 4 n = 2 n = 2 n = 7 n = 3 n = 5

  32. Sweep sync Samples Δt = 500ns t = 1,500ns t = 2,000ns t = 2,500ns t = 3,000ns t = 3,500ns t = 4,000ns t = 4,500ns t = 5,000ns V(t) Δt = 500ns V = 0mV V = -2mV V = -4mV V = +5mV V = -12mV V = -15mV V = -10mV V = -5mV count(t) n = 2 n = 4 n = 2 n = 2 n = 7 n = 3 n = 5 sync(t) t = 2,500ns

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