PAZ Instrument Internal Calibration Performance
J. del Castillo1, A. Lopez1, M. García1, P. Cifuentes1, B. Gómez1
1Spanish National Institute for Aerospace Technology -INTA-
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 Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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).
Pag.: 5 CEOS-SAR2015 - October 29th
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
CEOS-SAR2015 - October 29th
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
Internal calibration performance I
Raw cal pulses and replica analysis at SVT1B test Pulse delay, SNR, Dynamic Range, Spurious level
Pag.: 9 CEOS-SAR2015 - October 29th
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
CEOS-SAR2015 - October 29th
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
CEOS-SAR2015 - October 29th
Drift <1dB/12º @420seg
Drift 1σ accuracy <0.03dB70.2º
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
CEOS-SAR2015 - October 29th
All monitored elements inside [-20º,+50º] range
HOT 420s
COLD 420s
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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.
CEOS-SAR2015 - October 29th
0.005dB 1σ 0.008dB 1σ
0.23º 1σ 0.26º 1σ
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
CEOS-SAR2015 - October 29th
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
CEOS-SAR2015 - October 29th
Strip_single
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
Noise records analysis III In orbit test with calibration pulses
Rx cal pulses with RX boresight attenuated patterns.
Pag.: 17 CEOS-SAR2015 - October 29th
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.
PAZ Instrument Internal Calibration Performance and Foreseen In-flight Tests
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).
CEOS-SAR2015 - October 29th
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