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Star Tracker DSP code and operations (current status)

This document outlines the current operations and status of the Star Tracker DSP system, detailing key components such as program memory error protection, CRC checks, firmware updates, and acquisition commands for cameras. It includes an overview of the data reduction algorithm utilized for identifying centroids and standard deviations of the brightest stars. Monitoring commands and automatic acquisition processes are highlighted, along with the internal data buffering system and testing procedures, ensuring efficient and reliable star tracking capabilities.

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Star Tracker DSP code and operations (current status)

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  1. Star Tracker DSP code and operations (current status) • Program Memory Error Protection • Parity Check: booter->loader • CRC: loader->main program • Firmware Update • Acquisition commands implemented and tested (cameras on/off, image buffer selection, acquisition) • Data Reduction Algorithm implemented (centroid and standard deviations of the 10 brightest detected stars) • Epoch Gate Handling Commands (ast_newEpoch, ast_endEpoch) • Automatic Acquisition (we can download data while acquiring) • Reduced Data Buffer (current depth 100 frames, increasable up to ~1000) • Monitoring and general control commands (Clock, Housekeeping, … ) • People: M. Sarchioni, G. Alberti, A. Lebedev, E. Fiandrini

  2. Standard Work Cycle

  3. DAQ work flow

  4. Data Reduction Algo. • Each frame (512x512 pixel a 12 bit ≈ 384 KB) reduced to ~ 110 byte (can vary in future) • Returns: • Centroids and Standard Deviations of the 10 brightest stars' cluster (7 bytes per star) • Time stamp (milliseconds from last epoch) • Absolute Time of the last epoch (seconds from 01/01/1970 and milliseconds)

  5. Data Reduction Algo.

  6. Data Reduction Algo.

  7. Data Reduction Algo.

  8. Data Reduction Algo.

  9. Data Reduction Algo.

  10. Data Reduction Algo.

  11. Data Reduction Algo.

  12. Data readout(guidance by A. Lebedev) • raw data size is huge (262144 pixels, 524288 bytes) • limited serial port comunication (19200 baud) • output from ASTE goes to USCM buffer memory, 4096 bytes • compressed data ~ 110 bytes per frame • internal ASTE buffer contain 100 compressed frames • every time data are requested to ASTE, it deliver a fixed maximum number of frames (37) and the backlog • with a periodic reading of the buffers (ASTE and USCM) every ~ 5 second we do not expect any data loss

  13. Data readout status and action • test completed on FS set-up with ‘fake’ data (no cameras) • readout scheme implemented also on the flight software • test compressed data readout procedure on flight hardware • finalize readout procedure for flight • define and test raw data readout procedure

  14. Epoch Handling Procedure to set a new epoch: • Voiding the previous epoch setting the value to 0 with the ast_newEpoch command • Reset Pulse occurs • ASTE receives temporal informations of the pulse and sets the internal epoch (with the ast_newEpoch command again)

  15. To Do • Download some raw images: • in flight for algorithm tuning • SNR • CCDs faults • Tresholds • on ground • develop procedure and measure download time • Epoch Issue • Pulse per Epoch • Temporal information about every pulse • Find a compromise for the temporal interval between (reset) pulse (clock drift vs. lost frames)

  16. Some Image

  17. Some Image

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