paz instrument internal calibration...

PAZ Instrument Internal Calibration Performance

J. del Castillo1, A. Lopez1, M. García1, P. Cifuentes1, B. Gómez1

[email protected]

1Spanish National Institute for Aerospace Technology -INTA-

mailto:[email protected]

PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests

CEOSSAR2015 – October 29th Pag.: 2

Outline

PAZ Radar Instrument Overview Internal Calibration capabilities and approach Internal Calibration Data set TR Modules monitoring Internal calibration signals, replica and thermal behaviour Noise data analysis Summary


PAZ Radar Instrument Overview

X-band radar instrument on recurrent platform from TSX/TDX. Back end (RF & CE) recurrent from TDX X-band front-end composed by 12 panels with 32 elevation elements each. New PAZ developments:

TR modules and Subarrays. Panel distribution network and calibration network. Leaf amplifier assembly. Panel supply, Panel control and Remote Terminal units.

Pag.: 3

PCN

PCN

PCN

LA

A

PDN

LA

A

32 SAs

32 TRMs

Back end

Front end

Tx_in/Rx_out

Tx_in/Rx_out

Cal_in/Cal_out

Cal_in/Cal_out

PCU

PSU

RTU

CEOS-SAR2015 – October 29th


PCN

Internal Calibration capabilities and approach

Calibration capabilities drived by RF/CE design. Heritage from TSX/TDX Same 3 signal paths for one calibration pulse each:

Tx cal pulse: Sample of Tx signal is routed back to CE through cal network. Rx cal pulse Cal signal from CE is injected in Rx through cal network. CE cal pulse: common RF part covered in both Tx and Rx path.

Pag.: 4 CEOS-SAR2015 - October 29th

PCN

PCN

LA

A

PDN L

AA

32 SAs

Tx

Rx

RFE DCE

32 TRMs

CR

D

Cal_out

Cal_in

Back end

Front end


Internal Calibration capabilities and approach

Proper combination of calibration pulses allows: Instrument response Drift monitoring. Instrument Replica retrieval.

TRM monitoring by dedicated PN gating DTs execution Acquires TRM setting deviation (Drifted/Failed modules).


Warm up

Replica

Interleave cal

Radar pulses

ICAL, ATRM upgraded with PAZ particularities/constraints tested and validated with PAZ data.

Tool set from DLR PAZ Instrument sensors. PAZ new calibration network. PAZ Instrument thermal behaviour and automatic temperature compensation approach:

One Near state table for each TRM. One temperature compensation law for all TRMs


Internal Calibration Data set

Nominal imaging Data takes and only calibration pulses data takes available from 2 test with PAZ instrument: SVT1B and TVTB SVT1B: system verification test with Satellite at ambient temperature.

Data takes commanded via PAZ ground segment MCS. Data recorded at satellite delivered to CALVAL. Nominal imaging data takes (Strip, Scan, HR and HS) with embedded cal pulses 2 PN gating executions.

TVTB: Thermal vacuum/Thermal Balance campaign. Satellite in vacuum chamber at operation temperature limits (HOT and COLD phases)

420 seconds Only calibration pulses Data takes at temperature limits. PN Gating executions with nominal and redundant chain at different temperature.

CEOS-SAR2015 - October 29th Pag.: 6


TR Modules monitoring I

SVT1B data analysis (PN gating execution at ambient temperature) Module, row and panel execution(all TRM working)

Module execution (10 modules off Tx, 10 modules off Rx and half panel off)

Pag.: 7

Panel pairs jumps

detected No LAA at antenna offset measurement

CEOS-SAR2015 - October 29th


TR Modules monitoring II

TVTB data analysis (thermal vacuum thermal balance test results) PN gating Executions at HOT & COLD operation limits (nom and red)

Retrieved TRM reference by execution averaging.

Measured TRM monitoring performance.

Pag.: 8

Retrieved PAZ PNGating accuraccy *1 σ deviation from reference

Accuracy* Amp[dB] Phase[deg]

TX MODULE 0,14 5,16

RX MODULE 0,30 3,89

TX PANEL 0,07 2,35

RX PANEL 0,19 1,07

TX ROW 0,04 0,65

RX ROW 0,28 0,54



Internal calibration performance I

Raw cal pulses and replica analysis at SVT1B test Pulse delay, SNR, Dynamic Range, Spurious level


CE config RxBW 100MHz 150MHz 300MHz

µ σ µ σ µ σ SNR[dB] 26.30 1.6 27.19 1.64 26.57 1.34

D Range [AD units] 82.92 1.63 85.07 1.58 107.65 1.36

Spurious level[dB] -35.51 3.81 -34.43 4.05 -32.86 5.30

T rise[us] 1.2466 2.5ns 1.2336 3.5ns 1.2147 0.8ns

Data take FID01 SM-single

RxBw:100MHz

All DTs RxBw:100MHz


Internal calibration performance II

Pag.: 10

Replica IRF analysis versus BW with SVT1B test data:

Data take FID08 SM-dual RxBw:100MHz

CE config RxBW 100MHz 150MHz 300MHz

µ σ µ σ µ σ IRF_resol[m] 1.50 0 1.0 0 0.5 0 IRF_PSLR[dB] -18.22 0.04 -14.97 0.05 -14.55 0.05

IRF_ISLR[dB] 12.27 0.02 10.89 0.01 10.04 0.01

All DTs RxBw:100MHz



Internal calibration performance III

Instrument drift during 420sec Only cal pulses acquisitions at TVTB test

Pag.: 11

Drift <0.4dB/8º @420seg Drift <0.3dB/5º @420seg

HOT 420s DT COLD 420s DT HOT 420s DT

Freeze

Temp correction

Active


Drift <1dB/12º @420seg

Drift 1σ accuracy <0.03dB70.2º


TVTB HOT and COLD (instrument operation limits) Panel TR Modules Panel calibration network Calibration network LAA TR modules temperature evolution

Front-end Thermal behavior

Pag.: 12

Back end

Front end


All monitored elements inside [-20º,+50º] range

HOT 420s

COLD 420s


Internal calibration performance IV

Calibration network response variation with Temperature at TVTB

Pag.: 13

HOT 420s DT COLD 420s DT Cal network 2way

Hot amplitude

μ -0.66 dB

σ 0.004dB

Hot Phase μ 13.8º

σ 0.23º

Cold amplitude μ 0.80dB

σ 0.008dB

Cold Phase μ -5.7º

σ 0.26º

Replica correction Approach DT to DT amplitude and phase correction (up to 1.5dB) Intra data take not corrected due to cal. network stability.


0.005dB 1σ 0.008dB 1σ

0.23º 1σ 0.26º 1σ


Noise records analysis I

I-Q demodulator and ADC characterization with SVT1B noise record data I-Q Channels bias. I-Q amplitude unbalance. I-Q non orthogonallity.

Pag.: 14

I-Q parameters 100MHz 150MHz 300MHz µ σ µ σ µ σ

Ibias[ADC units] 0.53 0.02 0.68 0.02 0.65 0.02

Qbias[ADC units] 0.46 0.02 0.42 0.02 0.52 0.02

I-Q amp unbalance[ratio] 0.97 0.01 0.97 0.01 0.98 0.01

I-Q non orthogonallity[deg] 0.59 0.47 0.60 0.41 0.76 0.32

Data take FID01 SM-single RxBw:100MHz

All DTs RxBw:100MHz



Noise records analysis II

H-V channels Noise power unbalance

Pag.: 15

Strip_Dual

All DTs RxBw:100MHz

Data take FID08 SM-dual RxBw:100MHz

H noise power

V noise power

0.42 dB noise power delta

Rx response stability within Rx window Tested with echoes from SVT data takes No radar return Only noise Measured Power can be used to estimate Rx gain variation Phase variation can not be measured

0.5dBpp


Strip_single


Noise records analysis III Rx Gain setting accuracy test by noise analysis.

Noise analysis limitation:

Only Rx amplitude accuracy. No phase due to noise un-coherence. No valid for High Rx Attenuation states.

0.11dB 1σ Noise power above ADC

sampling level


Noise records analysis III In orbit test with calibration pulses

Rx cal pulses with RX boresight attenuated patterns.


PCN

LA

A

PDN

LA

A Tx

Rx

RFE

Same Rx attenuation all TRMs C

RD

Cal_out

Config TRM Rx RFE Rx Att ADC

1 0dB 30dB 35%

2 0dB 28dB 44%

3 0dB 26dB 55.5%

4 0dB 24dB 70%

5 -6dB 24dB 35%

6 -6dB 22dB 44%

7 -6dB 20dB 55.5%

8 -6dB 18dB 70%

9 … … …

RxAtt AD

C Increase Rx attenuation each 4 RFE Rx gain change

100 RxCal pulses per RFE Rx gain

No need to change Cal level attenuators to avoid ADC saturation at low RFE attenuation values.


Pag.: 18

Summary

PAZ internal calibration performance was tested with 2 Data sets. TRM monitoring test performed at SVT and TVTB:

Naming conventions checked (by blind test with switched off TRMs) First PAZ TRM reference generated and algorithm accuracy at Temperature operation limits derived. Amplitude 1sigma 0.2dB / phase 1 sigma 4º.

Internal calibration data analyzed:

Raw calibration pulses and replica quality parameters derived. Internal calibration accuracy checked at operation temperature limits with 420sec DTs. Instrument Drift < 0.4dB/4º.

Front-end Temperature evolution at operation limits comply with limits. Calibration network response stability and correction approach established. DT to DT factor correction needed. Up to 1.4 dB correction factor measured

Noise records analyzed from SVT:

I-Q demodulator and ADC characterization. Channels Bias and unbalance stable. Further analysis as H-V unbalance (0.4dB V-H delta in Rx-Gain), Rx gain stability in window length (0.5dBpp), Rx-gain setting error (0.1dB 1sigma).


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EuSAR2014 - June 05th Pag.: 19

paz instrument internal calibration...

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