1. THEMIS Instrument PDR 1 UCB, October 15-16, 2003 ESA & SST (ETC) Interface Board Preliminary Design Review Robert Abiad University of California - Berkeley

2. THEMIS Instrument PDR 2 UCB, October 15-16, 2003 Overview Overview of ETC Interface with particle instruments Processing of particle data Passing data back to DCB (main processor)

3. THEMIS Instrument PDR 3 UCB, October 15-16, 2003 Connections Instrument and DCB interfaces ESA commanding –ETC acts as translator –ESA & SST data collected –ETC collects data and processes it ESA & SST spin sectoring Other signals –SST commanding from the DCB –ESA & SST analog housekeeping wires to the DCB –SST clock from the DCB

4. THEMIS Instrument PDR 4 UCB, October 15-16, 2003 Connections DCB ETC SST ESA 8MHz EANA_HSK SANA_HSK ECMD_GATE ECMD_DATA ECMD_CLK ETLM_DATA ETLM_CLK STLM_REQ STLM_DAT TLM_DATA ETC_CMD SST_CMD SPIN/16384 SPIN/32 Shared board POR_L SPIN

5. THEMIS Instrument PDR 5 UCB, October 15-16, 2003 Instrument Interfaces Instrument interface protocols ESA command interface ESA telemetry interface

6. THEMIS Instrument PDR 6 UCB, October 15-16, 2003 Instrument Interfaces Instrument interface protocols SST command interface SST telemetry interface

7. THEMIS Instrument PDR 7 UCB, October 15-16, 2003 Processor Interfaces Processor interface protocols ETC command interface ETC telemetry interface

8. THEMIS Instrument PDR 8 UCB, October 15-16, 2003 Requirements Data production Slow Survey - 13 moments/data type (2 species x 2 instruments) Slow Survey - Reduced angle distribution/data type/Nspins Fast Survey - Full angle distribution/data type/Nspins Burst - Full angle distribution/data type/spin

9. THEMIS Instrument PDR 9 UCB, October 15-16, 2003 Requirements Moments There are 13 moments calculated for 4 different data types Moments are calculated using an entire spin of data  represents the 32 spin angles (64 in ESA Solar Wind mode)  represents elevation angle - 4 for SST and 16 for ESA E represents particle energy -16 for SST and 32 for ESA

10. THEMIS Instrument PDR 10 UCB, October 15-16, 2003 Requirements Moments (cont.) C is the count of particles at a particular field of view. This data comes from the instruments.  is the solid angle. This value is programmed into a lookup table by the processor. WP is a combined weighting and spacecraft potential correction. This value is calculated in the ETC using lookup tables and the equation: Where V is the spacecraft potential and N=0-3

11. THEMIS Instrument PDR 11 UCB, October 15-16, 2003 Distributions Purpose –Measure full particle angular distributions with equal solid angle resolution. Polar angle measurements are combined to produce equal solid angle bins and to reduce data volume. Full Distributions –ESA sees 512 fields of view in a spin (32 spin phase x 16 elevation angles). This gets reduced to 88 angle bins. –SST sees 128 fields of view in a spin (32 spin phase x 4 elevation angles). This gets reduced to 64 angle bins. –Solar wind mode gives higher angular resolution Reduced Distributions –For survey data covering more of an orbit due to low bandwidth –ESA and SST data reduced to 8 angle bins. –Electron pitch angle distributions Requirements

12. THEMIS Instrument PDR 12 UCB, October 15-16, 2003 Distributions (cont.) Burst Distributions –Burst are identical to full distributions in angular and energy makeup, but recorded every spin. All data will be converted from X bits to Y bits using a pseudo square-root compression scheme Use lookup tables to do angle translations Requirements  

13. THEMIS Instrument PDR 13 UCB, October 15-16, 2003 Electrical Diagram 128k SRAM 88 1716 Actel A54SX72S-CQ208 DCB AddrData 54AC24454AC14 52 ESA SST

14. THEMIS Instrument PDR 14 UCB, October 15-16, 2003 Electrical Diagram

15. THEMIS Instrument PDR 15 UCB, October 15-16, 2003 Processor Requirements Table Loading 31 tables totaling 45 kBytes –4  - computed on board –8 distribution lookup tables - loaded from ground –5 exponential lookup tables - in EEPROM –14 energy lookup tables - computed on board Commanding 1 spacecraft potential command/spin Less frequent setup commands –Number of spins to collect data –Number of angles data is being binned into Maintaining collected data 13 DMA channels to mass memory Inserting headers into data

16. THEMIS Instrument PDR 16 UCB, October 15-16, 2003 Processor Requirements

17. THEMIS Instrument PDR 17 UCB, October 15-16, 2003 Power Power estimation Actel 205mW + 2 SRAM (25mW/MHz) 50mW + Transceivers 20mW = 275mW

18. THEMIS Instrument PDR 18 UCB, October 15-16, 2003 Schedule Board design Due to finish by October 31 Actel design and debug November 1 - January 31

19. THEMIS Instrument PDR 19 UCB, October 15-16, 2003 Simulation, Simulation, Simulation GSE + DCB light DCB to load tables and issue commands GSE to produce a known data set in instrument form DCB to receive data and pass it on to GSE GSE to collect data and put it into computer Testing Plan

20. THEMIS Instrument PDR 20 UCB, October 15-16, 2003 Issues Evolving requirements Need for core requirements separate from enhancements Additional duties