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

RFS FSW Requirements

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 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

Initialization FSW Initialization of PFB 1.Verify EEPROM PFB table. 2.Decompress ½ waveform (16k pts) 3.Reverse waveform 4.Repeat for High and Low gain with commanded scale factors. 5.EEPROM required : 16 KB where each byte is the derivative of the waveform. Max delta = +/ Only ½ table 16K points stored. LFR table is (1/10) * HFR table. Two Arrays Needed : LFR & HFR (LFR[i] = HFR[i]/10

Initialization FSW Initialization of Sine Table 1.Verify EEPROM Sine table (1/4 wave of 8192 points). 2.Build Full Sine table in RFS memory a)Copy ¼ wave b)Copy & Reverse ¼ wave c)Invert & reverse ½ wave 3.EEPROM required : 4 KB (2K points)

Compression FSW Compressor Function 1.Inputs CCSDS packets 2.Uses 32-sample 16-bit chunks 3.Compresses to packed n-bit wide derivative + 4-bit key. 4.Adds keys to the end of the packet 5.Discards expanded packets 6.Replaces original packet in situ Data Can Be Compressed at Max TM Rate (This data taken from a slower processor.) FSW Waveform Compression 1.Used to play raw waveforms 2.Will try this on spectra

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 Plasma Tracking

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. Issues