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Solar Probe Plus FIELDS RFS Peter R. Harvey Oct 25, 2013

Solar Probe Plus FIELDS RFS Peter R. Harvey Oct 25, 2013. RFS FSW Requirements. Processing. Processing Baseline Cycle = 2^N (=8 def.) DCB Seconds Modes [a] BasicSurvey , [b] DirectionFinding , [c] BurstMode , [ d] Calibration, and [e] Engineering (Raw waveforms ).

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Solar Probe Plus FIELDS RFS Peter R. Harvey Oct 25, 2013

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  1. Solar Probe Plus FIELDS RFS Peter R. Harvey Oct 25, 2013

  2. RFS FSW Requirements

  3. Processing Processing • Baseline Cycle = 2^N (=8 def.) DCB Seconds • Modes • [a] BasicSurvey, [b] DirectionFinding, [c] BurstMode, • [d] Calibration, and [e] Engineering (Raw waveforms). • Single Channel Pair Focus • “M” Spectra accumulated as rapidly as possible (9 to 17) • Data Buffered in SRAM until processed • Single Gain in an averaging period

  4. Processing Processing FPGA Processing Step 1. Data Collection If needed, repeat at low gain Step 2. PFB process w/gain adjust Step 3. FFT processing (Also, FSW computes offsets X1,X2) FSW Processing Step 1. Identify Dust Impacts Step 2. Reduce frequencies Step 3. Median-Filter Spectra (Auto1,2 and Cross) Step 5. Compute Phase & Coherence

  5. Initialization FSW Initialization of PFB Verify EEPROM PFB table. Decompress ½ waveform (16k pts) Reverse waveform Repeat for High and Low gain with commanded scale factors. EEPROM required : 16 KBwhere each byte is the derivative of the waveform. Max delta = +/- 2. Only ½ table 16K points stored. LFR table is (1/10) * HFR table. Two Arrays Needed : LFR & HFR (LFR[i] = HFR[i]/10

  6. Initialization • FSW Initialization of Sine Table • Verify EEPROM Sine table (1/4 wave of 8192 points). • Build Full Sine table in RFS memory • Copy ¼ wave • Copy & Reverse ¼ wave • Invert & reverse ½ wave • EEPROM required : 4 KB(2K points)

  7. Compression FSW Waveform Compression Used to play raw waveforms Will try this on spectra FSW Compressor Function Inputs CCSDS packets Uses 32-sample 16-bit chunks Compresses to packed n-bit wide derivative + 4-bit key. Adds keys to the end of the packet Discards expanded packets Replaces original packet in situ Data Can Be Compressed at Max TM Rate (This data taken from a slower processor.)

  8. Plasma Tracking Plasma Tracking Using Spectra Data • On Bepi-Columbo, used a simple “first peak” algorithm. Positive going peak. • Logic (discussed in Meudon): • [1] Use a 40 bin window to average for 10 spectra then look for the peak in that window; if there is no peak, go to [2]. • [2] Use the last full 2048 point spectra to find a peak. • [3] Telemeter 20 points centered on the peak

  9. Issues Issues Dust Detection • On STEREO, common to get 50 dust hits per second. (Sometimes max rate of over 6000/second!) 50/second = 20 msec per hit. • In 0.8 msec x 10 samples = 8 msec, we have a good chance to get clean spectra with median filtering • In 8msec x 10 samples = 80 msec, probably going to get hit 4 times.

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