Solar Probe Plus FIELDS

RFSPeter R. Harvey

Oct 25, 2013

RFS FSW Requirements

Reqmt Title Description Verif. Parent Parent Description

FSW.RFS-1 Initial StateRFS_INIT shall initialize the module and define its hardware initial state so the module works correctly.

Inspect SPF.FSW-02

FSW shall implement the spacecraft interface protocol:[a] configuring to a known initial state on power on;[b] using commands and time messages as in the ICD; [c] generating engineering telemetry as in the ICD; [d] capable of entering a safe state for power down.

FSW.RFS-2Receive Commands

RFS shall receive and execute commands to the module at up to 32Hz, and complete those commands in <1/10 interrupt period.

Test SPF.FSW-02

FSW shall implement the spacecraft interface protocol:[a] configuring to a known initial state on power on;[b] using commands and time messages as in the ICD; [c] generating engineering telemetry as in the ICD; [d] capable of entering a safe state for power down.

FSW.RFS-3Provide Engineering HSK

RFS shall provide housekeeping telemetry Test SPF.FSW-02

FSW shall implement the spacecraft interface protocol:[a] configuring to a known initial state on power on;[b] using commands and time messages as in the ICD; [c] generating engineering telemetry as in the ICD; [d] capable of entering a safe state for power down.

FSW.RFS-4

Operate Poly-Phase Filter Logic

RFS shall be able to operate the FPGA PFB logic:[a] providing scale factors from EEPROM to the PFB memory;[b] initialize PFB logic to default settings;[c] controlling sample selection;[d] identifying error conditions.

Test DCB.FSW-05FSW shall collect and telemeter Quasi-Thermal Noise data

FSW.RFS-5

Generate SpectraRFS shall generate Spectra:[1] for a list of sources (QTN & Radio);[2] using high and low speed conversion rates;[3] using high and low gain A/D channels;[4] combining N spectra together for each source;[5] rejecting spectra with noise issues such as dust spikes;[6] rebinning spectra to higher and lower resolution bins as in the CTM.

Test DCB.FSW-05FSW shall collect and telemeter Quasi-Thermal Noise data

FSW.RFS-7

Remove Offsets RFS shall be able to periodically:[a] determine the DC offset of the incoming waveforms;[b] provide that offset to the PFB logic.

Test DCB.FSW-05FSW shall collect and telemeter Quasi-Thermal Noise data

FSW.RFS-8Support Diagnostics RFS shall be able to support diagnostics:

[a] loading test waveforms into the PFB logic;[b] telemetering collected raw waveforms.

Test DCB.FSW-05FSW shall collect and telemeter Quasi-Thermal Noise data

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

Processing

Processing

FPGA Processing Step 1. Data CollectionIf needed, repeat at low gainStep 2. PFB process w/gain adjustStep 3. FFT processing

(Also, FSW computes offsets X1,X2)

FSW Processing Step 1. Identify Dust ImpactsStep 2. Reduce frequenciesStep 3. Median-Filter Spectra

(Auto1,2 and Cross)Step 5. Compute Phase & Coherence

Initialization

FSW Initialization of PFB1. Verify EEPROM PFB table.2. Decompress ½ waveform (16k pts)3. Reverse waveform4. 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 = +/- 2.

6. 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 Table1. Verify EEPROM Sine table (1/4 wave of 8192 points).2. Build Full Sine table in RFS memory

a) Copy ¼ waveb) Copy & Reverse ¼ wavec) Invert & reverse ½ wave

3. EEPROM required : 4 KB (2K points)

Compression

FSW Compressor Function1. Inputs CCSDS packets2. Uses 32-sample 16-bit chunks3. Compresses to packed n-bit wide

derivative + 4-bit key.4. Adds keys to the end of the packet5. Discards expanded packets6. Replaces original packet in situ

Data Can Be Compressed at Max TM Rate(This data taken from a slower processor.)

FSW Waveform Compression1. Used to play raw waveforms2. Will try this on spectra

Plasma Tracking Using Spectra Data

Þ On Bepi-Columbo, used a simple “first peak” algorithm. Positive going peak.

Þ Logic (discussed in Meudon):Þ [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]. Þ [2] Use the last full 2048 point spectra to find a peak.Þ [3] Telemeter 20 points centered on the peak

Plasma Tracking

IssuesDust DetectionÞ On STEREO, common to get 50 dust hits per second. (Sometimes max

rate of over 6000/second!) 50/second = 20 msec per hit.Þ In 0.8 msec x 10 samples = 8 msec, we have a good chance to get

clean spectra with median filteringÞ In 8msec x 10 samples = 80 msec, probably going to get hit 4 times.

Issues