High speed DSP for infrared space camera

Martin Grim

Contents

• SRON and the Space Kids Consortium• Context• Kinetic Inductance Detector• Read-out principle• System architecture• Software

www.spacekids.euwww.sron.nl

www.facebook.com/sron.nl

2

SRON and Space Kids consortium

• SRON" One of 8 Scientific Institutes of NWO" Scientific research in and from outer space" Astrophysics, exo planets, earth and climate" Instrument realization from start to finish

• Space Kids consortium

3

Context

• Why infrared?" Research into star, galaxy and planet formation

Star formation only visible as glowing dust" Research into the young universe (approx 600·106 years old)

Expanding universe leads to red shift (towards infrared)

• Big questions

5

What is the universe made of and how does it evolve?

How do galaxies, starts and planets form and evolve?

Are we alone?

Orion

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Future (IR) space instruments

• Extremely cold primary mirror (4 K)• Extremely sensitive detector• Dedicated detector read-out

" Low noise" High speed" High multiplex factor

7

SPICA (launch 2025?)

Kinetic Inductance Detector

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0.1 mm

Ground planeNo radiation absorption Antenna

In lens focus

Al central lineRadiation absorbed

ResonatorLength sets F0

5mm = 6 GHz

FeedlineConnects all KIDs

to readout

Lens

Si lenses @ chip back

1 mm

Current pixel design

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Kinetic Inductance Detector

• Very sensitive super conducting radiation detector" operate at 100-300 mK" resonance changes due to incoming radiation" measure change in amplitude/phase of carrier" all carriers for all KID simultaneously present

Radiation

Si Lens21

1 2Readout signal ~GHz

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• KID read-out" integration of signal read from all detectors" FFT on integrated signal" Masking to select the bins which correspond to a KID resonance

4.056 4.058 4.060 4.062 4.064 4.066 4.068

-35

-30

-25

-20

-15

S21

[dB

]

F [GHz]

no light LED on

KID read-out system

Readout principle

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High level requirements

• carriers 2000 (pixels)• blind carriers 10%• data points 216 or 219 complex points• analog bandwidth 2.0 GHz• sampling speed 2.0 Gs/s per channel (I, Q)• frame averages 24 or 192 (216 vs 219)• system noise to carrier ratio 94 dBc/Hz

" DAC, ADC, CLK, PSU, RF

• RF, DACs, ADCs synchronized external 2.0 GHz clock• FFT: 160 or 1280 Hz (219 vs 216)

13

Chosen system

• COTS hardware• FMC and Virtex7 technology• QDR2 memory• Full integration

• Focus on firmware/DSP" PC based SW control" Science pipe line

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Space KIDs prototype system

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4DSP VP780 FMC carrier board

FMC126

2000 pixel KID array

RF

elec

troni

cs

QDRIImemory

Clocksynthesizer

reference clock

2 Gs/s I

PC

Command & Control of - VP780 + DAC- VP780 + ADC + wola + FFT

Display of science dataDisplay of housekeeping data Interface to science pipeline

2 Gs/s Q

2 Gs/s I4 Gs/s10 bitADC

4DSP VP780 FMC carrier board

Virtex 7- waveform generation

FMC230

4 Gs/s14 bitDAC

OpenVPX system board ComEth 4410a Ethernet Switch

Virtex 7- wola- FFT

C&C + science

GbE

C&C + science

320 Hz science data

C&C

C&C

2 Gs/s Q

Space KIDs readout hardware

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Current implementation

• In firmware" Carrier comb processing" WOLA performed" FFT performed" Carrier select

• Command and Control" SRON generic instrument control software

Control of hardware Control of measurement Displaying (level 0/1) science data Displaying health

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Software: today and future

• Carrier comb " Python science control software (offline, PC)

Find KIDs in spectrum: 2nd derivative, check against threshold Calibrate signal: remove modulated carriers, flatten base Calibrate ADC and DAC frequency dependent gain Calibrate I-Q phase difference Deal with strong and weak sources

• Space System:" Perform the above in embedded system (semi real-time)" Add

Low power, low memory, low μP performance Static memory allocation Lossless data compression Fault management Redundancy (near) 100% code coverage

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Space KIDs: the future

• Finish current research• Investigate migration to space-like system• Investigate embedded processing • Investigate alternatives for WOLA and FFT• Go to TRL 5 or 6 within 2-3 years?

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Questions

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