GoetzFIELDS iCDR - TDS Solar Probe Plus - FIELDS Instrument CDR Time Domain Sampler TDS Keith Goetz University of Minnesota [email protected] 1

Goetz 1FIELDS iCDR - TDS

Solar Probe Plus - FIELDSInstrument CDR

Time Domain SamplerTDS

Keith Goetz

University of Minnesota

[email protected]


Agenda

• Science• Changes• Performance Requirements• Block Diagram(s)• Design Description & Specifications• Resources • Breadboard/Engineering Model Testing• Parts & Materials• Verification Plans• Peer Reviews• Schedule & Open Work• Issues


Time Domain Sampler - Science

• Time Domain Sampler (TDS) is based on previous instruments– Based most recently on STEREO instrument

• Gathers impulsive events – voltage as a function of time– Centered peaks– Simultaneous sampling on all channels– Fixed sampling rate – 1.92MSa/s which is ~160Mb/s 24x7

throughput– Programmable effective sampling rate– Programmable event duration

• Events have peaks - triggered– After that, flight software scores event based on programmable

criteria– Quality can be adjusted – up or down - after the fact– When telemetry is available (nominally to DCB), best event is

sent– When memory is needed (for a new event), worst event is

deleted• Event selection can be based on quality or not –

honesty– Delivered bit-rate is highly programmable – nominally 10kb/s

• Low rate stream gives peak activity as a function of time


STEREO snapshot


STEREO snapshots

BurstActivity


Dust


Big Dust


Waveform and Particles

SamplesΔt = 500ns

CLK~2MHz

V(t)Δt = 500ns

count(t)


Waves and Particles

SamplesΔt = 500ns

V(t)Δt = 500ns

count(t)

t = 1,500ns t = 2,000ns t = 2,500ns t = 3,000ns t = 3,500ns t = 4,000ns t = 4,500ns t = 5,000ns

V = 0mV V = -2mV V = -4mV V = +5mV V = -12mV V = -15mV V = -10mV V = -5mV

n = 2 n = 4 n = 2 n = 2 n = 7 n = 3 n = 5


TDS Heritage

• Time Domain Sampler (TDS) is based on STEREO instrument– The first instrument fully integrated on both spacecraft and

the only instrument never to come off

• Changes – Science – close to the sun– Plasma frequency up from 10’s to 100’s of kHz – shock time

scales are faster– TDS samples at ~2MSa/s and ~1MHz Nyquist

• Programmable down-sampling– Continuous sampling – reduced power supply load variations– Direct deposit – increases duty cycle – eliminates event length

limit– Wave-particle correlation with SWEAP


Time Domain Sampler – FIELDS2

• Part of increased FIELDS reliability, TDS has DPU-like functions– Center of FIELDS2– TM/TC Interface to S/C– Handles some FIELDS subsystems

• MAGi, AEB2, LNPS2• SWEAP

– Interface to FIELDS1/DCB for TM/TC and timing synchronization– Interface to SWEAP for wave particle correlation,

communications and timing• Similar functionality in STEREO instrument

– Multiple instruments– S/C TM/TC interface


TDS Changes Since iPDR

• LVDS protection added to S/C interfaces• Eliminated in-flight E-parallel measurement

– Simplified in-flight calculations– To be done on the ground

• LVDS protection added to SWEAP interface– A new PAY requirement is coming soon


TDS Requirements

• TDS-01 Mission Length – TDS Components shall be selected to withstand the

environment of SPP for the duration of the extended mission (possible launch delay).

• TDS-02 Spacecraft Interface Compliance (General) – TDS shall implement the spacecraft interface protocol…

• TDS-03 Timing from S/C– TDS shall provide latching facility upon detection of the "Virtual

1PPS" S/C timing signal…• TDS-04

– Timing from DCB TDS shall provide an electrical interface to the Data Control Board capable of…


SWEAP Requirements

• TDS-05 SWEAP Interface - CDI– TDS shall provide an electrical interface to the SWEAP

instrument capable of sending CDI commands, receiving CDI messages:

• [a] sending Command/Data Interface (CDI) messages to SWEAP;• [b] receiving SWEAP status and burst information from SWEAP;• [c] sending TDS time-keeping information;• [d] sending TDS clock synchronization.

• TDS-06 SWEAP Interface – Particles– TDS shall provide an electrical interface to the SWEAP

instrument capable of:• [a] receiving particle count information from SWEAP• [b] receiving particle synchronization and state information from

SWEAP

• TDS-17 SWEAP Interface – Do no harm– TDS shall provide protection in the LVDS interfaces to/from the

SWEAP instrument so as to avoid allowing a single TDS failure to damage SWEAP.


MAG Requirements

• TDS-07 MAG Interface – CDI– TDS shall provide an electrical interface to the MAG Electronics

capable of:• [a] setting control registers• [b] receiving MAG Science and Engineering data• [c] provide MAG AC heater synchronization


AEB Requirements

• TDS-08 Antenna Electronics Board Interface (AEB)– TDS shall provide an electrical interface to the Antenna

Electronics Board capable of:• [a] setting Biasing D/A converters and relays• [b] reading back the biasing voltages• [c] provide DC-DC converter synchronization


LNPS Requirements

• TDS-09 Low Noise Power Supply Interface (LNPS)– TDS shall provide an electrical interface to the Low Noise

Power Supply capable of• [a] setting control registers for Power Control and Housekeeping

Channel• [b] receiving an analog housekeeping signal• [c] provide DC-DC synchronization


TDS Requirements

• TDS-10 Time Domain Sampler Control– TDS shall provide electrical interfaces to the Time Domain

Sampler data acquisition system capable of:• [a] setting TDS instrument modes• [b] receiving TDS instrument data

• TDS-11 TDS Memory Management– TDS shall include memory such that:

• [a] is capable of storing ~20 TDS snapshot events• [b] allows best available event to be sent to telemetry

• TDS-12 TDS Instrument Calibration– TDS analog science and analog housekeeping conversion

coefficients shall be determined and provided prior to S/C Integration to include gain, phase and timing


Science Requirements

• TDS-13 E Signals– TDS shall provide an electrical interface capable of:

• [a] signal processing and measurement of the low frequency component of E-Field signals

• TDS-14 E Signals– TDS shall provide an electrical interface capable of:

• [a] signal processing and measurement of the AC or plasma frequency (ranging to ~1MHz) component of E-Field signals."

• TDS-15 B Signals– TDS shall provide an electrical interface capable of:

• [a] signal processing and measurement of the AC or plasma frequency (ranging to ~1MHz) component of B-Field signals (single axis)."

• TDS-16 Instrument Calibration– TDS shall provide calibration parameters and algorithms so as

to allow conversion from telemetry units to physical units (gain and offset per channel) prior to S/C Integration.


FIELDS block diagram


TDS Block Diagram


TDS Block Diagram – “DPU” additions


TDS – Single Board Data Acquisition System

• Centers on RTAX4000 FPGA daughter board– Holds all logic, interfaces and LEON 3 processor instantiation

• TDS event data gathered by 16-bit ADCs at ~2MSa/s– Multiplexed 16-bit data bus

• Simultaneous acquisition of SWEAP particle counts• TDS event data stored directly into dedicated event

memory– 16MB event SRAM – 8 parts – 512k by 32bits– Circular buffers

• Processor support– 8-bit data bus

• Local SRAM w/ ECC• Local boot PROM (some in FPGA?)• Local program EEPROM

• S/C serial interfaces• CDI interfaces to DCB, MAG, SWEAP• Device interfaces – AEB, LNPS• Mezzanine interface

– Diagnostic UARTs


TDS EM1 – top and bottom


FIELDS2

LNPS2MAGiAEB2


GSEOS on the Bench – FIELDS2


MAG Simulator


TDS Channel 1


TDS Channel 2


TDS Channel 3


TDS Channel 4


TDS Channel 5


TDS Big Screen


Resources

• TDS mass CBE is 435g (not counting structure) with 500g NTE

• TDS power CBE is 2.36W secondary with 2.50W NTE– May increase on ±6V– +1.5V and +3.3V will increase when hot– Measured values as a function of temperature in TV

• TDS science bit-rate to DCB (flash) is ~10,000 b/s uncompressed– Highly flexible (by command)

• 1kbps to 100kbps


Parts

• Parts list is complete– Most parts are ok– Some issues remain with SE issues – being worked– One part needs further testing – ADC AD7621– De-rating worksheets are well along

• Selected ADC is great – but plastic – AD7621– Astrium/ESA testing suggests we’ll be ok (only SEU/SEFI

sensitive)– Beam testing planned at TAMU– Topless parts are in hand – to be attached to demo boards for

the beam• Test software is coming along

– As a risk mitigation, an over current circuit breaker is in current design


Reviews

• FIELDS iPDR held on 13-14 November 2013– No actions directed specifically at TDS

• TDS circuit, FPGA and FSW peer reviews held on 5 December 2014– Electronics review provided 7 recommendations – 6 unique

• 3 are complete, 3 will be done in the near term– FPGA review provided 7 recommendations

• All will be completed in the near term– Flight Software review provided 7 recommendations

• 4 are complete and 3 will be completed in the near term

• FIELDS iCDR held on 14-16 January 2015


Next

• Continue development work with EM1– FPGA

• AEB control• SWEAP interface operational

– FSW– Calibrations and trimming– Closed box operations

• Deliver EM1 to UCB and integrate FIELDS1 with FIELDS2– Continue with the full FIELDS level I&T at UCB– Run a full FIELDS CPT

• Populate a second board – EM2 (happening now)– Continue development work with EM2 at UMN

• Beam testing ADC• Move to flight schematics, layout


Conclusions

• TDS design is well advanced• TDS EM is in great shape

– Better than usual at this point (iCDR)• Design meets or exceeds all requirements

– Except SWEAP protection addition which will be added to FM• Overall power

– We’re only now getting to good power estimates for running hot

• Based on LASP’s testing with DFB• Results are very promising – power increase when hot is less than

expected

• LVDS protection needs to be extended to SWEAP communications

• TDS is on track for flight


Backup Slides


Electronics Peer Review Recommendations

Action Name Description Response Closed?TDS-01 LF Signals to TDC Need to decide if LF signals will go to TDS before CDR To be done before 1 April

TDS-02 ADC Protection DiodesConsider protection diodes on housekeeping ADC input to stay within spec. Needs a test to verify the series resistor provides enough protection against out of range transients. Should coordinate a test between FIELDS and SWEAP

To be done before 1 April

TDS-03 SWEAP ICD Complete updated SWEAP to FIELDS ICD including any particle pulse signal constraints. To be done before 1 April

TDS-04 Housekeeping ADC Supply

Housekeeping ADC is powered from a different supply than the FPGA.There may be an overstress problem when one supply is active and the other is off. At the very least, series resistors should be placed on the signal lines between the FPGA and the ADC to protect each device from overcurrent. Operationally, there could be a 0.6V differential in the two "Vcc"s. This should be checked to make sure the operation is reliable.

Series resistors will be installed in FM

TDS-05 LF Input Impedances

The TDS analog LF channel inputs for the nominal V5 and optional (TDS-06) V3..4 channels have an effective input impedance of ~28-kohms to analog ground arising from the voltage divider used to bring +/- 115-V LF dynamic range down to the range needed by the TDS.

This input impedance is at least a factor of 5 less than the expected impedance of all the other end users of the LF channels (AEB bias drivers; AEB FGND driver; DFB LF analog inputs) in parallel (at least 100-kohm or more), and so will add a significant load the LF preamp outputs.

It's likely that this extra loading will lead to performance issues on the LF channel (distortion), and so I Recommend that the TDS team consider increasing the resistances used in the V5 input voltge divider to levels comensurate with those found on the AEB and DFB.

Input impedance will be adjusted on the EM and FM models.

TDS-07 ADC input capacitorsRE the ADC128S102: consider adding 1nF caps on all the analog inputs. This is a datasheet recommendation which was found to be necessary (learned when bringing up DCB-ETU#1).

Capacitors will be added on FM.

Documents

GoetzFIELDS iCDR - TDS Solar Probe Plus - FIELDS Instrument CDR Time Domain Sampler TDS Keith Goetz University of Minnesota [email protected] 1