PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER
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PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER

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    PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER Presentation Transcript

    • National Space Science Center Chinese Academy of Sciences PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER Xiaolong Dong, Di Zhu CAS Key Laboratory of Microwave Remote Sensing National Space Science Center, CAS PO Box 8701, Beijing, China dongxiaolong@mirslab.cn, zhudi@mirslab.cnIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Outline of the Presentation• Introduction to the Mission• Specifications of SCAT• Description of SCAT system• Simulation of SCAT system performances• Progresses• SummaryIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences • Two payloads: CFOSAT Mission – SWIM (Sea Wave Investigation and Monitoring by satellite) • A Ku-band real aperture radar for• CFOSAT: Chinese French Oceanography measurement of directional ocean wave spectra; SATellie – SCAT (SCATterometer)• Launch plan: 2014 • A Ku-band rotating fan-beam radar• Mission Objectives: scatterometer for measurement of monitoring the wind and waves at the ocean ocean surface wind vector. surface at the global scale in order to improve: – The wind and wave forecast for marine meteorology (including severe events) – the ocean dynamics modeling and prediction, – our knowledge of climate variability – fundamental knowledge on surface processes linked to wind and waves IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote Sensing July 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Mission-measurement requirements• Joint measurement of ocean surface wind vector and sea-state parameters from radar – Both wind vector and wave parameters can be measured using active micro-wave remote sensing (heritage of altimeter, sactterometer and SAR missions, and airborne radar measurements) – Wind vector => optimal configuration at medium incidence angle (20-50°) – Wave spectra => optimal configuration at low incidence angle (< 15°)• CFOSAT mission with two payloads – SWIM: wave scatterometer: multi-beam Ku-Band radar at low incidence – SCAT: wind scatteromer: Fan beam Ku-Band radar at medium incidence IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote Sensing 4 July 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS) 4
    • National Space Science Center Chinese Academy of Sciences Mission-Wind Vector Payload -SCAT• A Ku-band rotating fan-beam radar scatterometer (Ku-RFSCAT) for sea surface wind vector retrieval by measurement of the sea surface backscattering coefficient. Rotating fan-beam antenna• Adapted to the platform constraints (small size);• 2 fan beams (HH & VV) cover incident Nadir Point angles from 26 degree to 46 degree from nadir• scanned with a rotation speed of around footprint 3.5 rpm.• For each of the ground resolution cells, more than four looking angles can be obtained to retrieval wind vector information.IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 5 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Characteristics of CFOSAT SCAT• Wide swath by rotating of beam; – Decided by outer edge of incident angle of beam• More number of azimuth look angles by overlap of beam; – Decided by flying speed, rotating speed and beamwidth• NRCS/sigma 0 dependent on antenna beam; – Decided by local antenna gain along elevation• Single antenna for all azimuth directions; – No inter-beam balance required – But azimuth fluctuation may exist due to rotating mechanismIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Azimuth look angle combinations for surface resolution cells Overlap between adjacent scanns for large number of azimuth view for each pixel. Dual polarization is used Surface resolution cell 1 to improve retrieval of outer and center part of the swath Track of nadir porints Surface resolution cell 2IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Specifications for SCAT• Objectives: – Measurement of global surface sigma 0 – Retrieval of global ocean surface wind vector• Data requirements – Swath width: >1000km – Surface resolution: 50km (standard); 25km (goal) – Data quality (at 50km resolution) – ° precision: • 1.0dB for wind speed 4~6m/s • 0.5dB for wind speed 6~24m/s – Wind speed: 2m/s or 10% @ 4~25m/s – Wind direction: 20deg @ 360deg for most part of the swath• Life time: 3yrsIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Specifications of SCAT Ku-RFSCAT ParametersAntenna Spinning rate : 3.5 rpmPolarization: VV, HHPRF/channel: 75 Hz/channelPulse peak power (Pt): 120 WPulse bandwidth (B): 0.5 MHzPulse duration (τp): 1.3 msSwath width: 1000 kmReceive gate length(Tg): 2.82 msReceive gate delay: 3.74 msInclination: 97.5 degIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Description of SCAT system• System overview• Choice of system type• Operation mode• System configuration• Key parametersIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences System overview• Ku-band rotating fan-beam scatterometer – Platform dimension – Technology heritage – Available GMFs• Long LMF pulse with de-ramp pulse compression – TX: 1.35ms – RX: 2.72 ms• Digital I-Q receiver with on-board pulse compression processing and resolution cell regrouping• TX/RX channel except antenna and switch matrix identical primary/backup design to ensure liabilityIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Choice of system type -Why rotating fan beam?• Why rotating beam? • Why rotating fan beam? – Overlap of surface coverage with – Lower rotating speed to ensure SWIM is requirement, nadir gap life time of rotating mechanism; should be avoided. – Multiple incident angles for – Deployment of multiple fan-beam better wind direction retrieval; antenna is not allowed due to – Large incident angle ranges platform capability. (20~46°) for investigation of – Large swath at a relatively low ocean surface scattering orbit (~500km) requires scanning. characteristics, by compensating with SWIM (0~10°) IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote Sensing July 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Other constraints• Antenna dimension: <1.2m• Available Pulsed Ku-TWTA: <140W• Available TWTA PRF: >150Hz• Data rate: <220kpbs• Rotating speed and mechanism lifetimeIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Operation mode• Normal mode: dual polarization with rotation;• Test/cal mode: – raw waveform with lower PRF; – Including both rotating mode and fixed pointing mode;• Single polarization modeIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences System configuration• Antenna subsystem • Power amplifier subsystem – Antenna and feeding network; – TWT and EPC – Scanning mechanism; • Digital subsystem – Servo controller; – Signal generator;• RF subsystem – System controller; – Switch matrix; – Signal processor; – RF receiver; – Communication controller;• RX/TX electronics subsystem • Secondary power supply subsystem – IF receiver; – DC-DC power converter; – Frequency synthesizers; – TC/TM module – TX up-converter • WG & cable assemblyIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences System DiagramIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of SciencesSystem configuration • Interface with structure subsystem – Antenna and part of the servo mechanism installed outside the satellite; – Other equipments installed inside the satelltie IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote Sensing July 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • Basic radar parameters Parameter Specifications Frequency 13.256GHz Signal bandwidth 0.5MHz Internal calibration precision Better than 0.15dB Receiver NF ≤2.0dB Insertion loss of TX channel ≤1.5dB Insertion loss of RX channel ≤3.0dB Transmitting power (peak) 120W Pulse width 1.35ms PRF 2×75=150HzEUMETSAT/ESA Scatterometer Science Conference 2011April 11-13, Darmstadt, Germany
    • National Space Science Center Chinese Academy of Sciences Optimization of radar parameters• Optimization: trade-off between SNR, measurement samples of each look and number of looks. maximization of wind vector retrieval performance – Surface resolution – Signal bandwidth – Rotating speedIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Resolution in azimuth direction & azimuth beam-width• Fan beamlower gainantenna as long as possible• Decided by antenna beamwidth• Limited by satellite dimension: ≤1.2m• Beamwidth ~1.1 deg resolution in azimuth direction: 10.5~14.5kmIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • Design of rotating speed • Trade-off between independent sigma 0measuremrent samples for single look and number of looks • Optimization of 3.5rpmEUMETSAT/ESA Scatterometer Science Conference 2011April 11-13, Darmstadt, Germany
    • National Space Science Center Chinese Academy of Sciences Resolution in elevation direction & signal bandwidth• Low SNR due to low antenna gain• Bandwidth 0.5MHz resolution:380~650m• On-board non-coherent re- grouping to improve sigma 0 precision resolution of 5km IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote Sensing July 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Onboard processing • Reduce data rate to ~220kbps • Downlink data resolution: ~10km(az) × 5km(el) – (original resolution: 10km(az) × (<1km(el)) • Signal+noise processing & noise-only processingIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Internal Calibration Loop P1 K1 C1 LPF1 P31 P21 Circulator TWTA P22 P32 K6 C2 K2 D K3 K5 A Ns LPF2 K4 P31 P32 Compositions: •C1,C2:directional couplers Ports: •K1,K2,K3,K4:ferrite switches •P1: BJ-140 to TWTA •K5,K6:mechanical switches •P2: BJ-140 to antennas •LPF1/2:EMC filters •P3: BJ-140 to RF receiver •D: power monitoring detector •Ns:internal noise sourceIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Simulations of system performances• Simulation model• Simulation of precision• Simulation of wind vector retrieval performanceIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Simulation modelIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Simulation of ° precision• Modeling 2 G2  Pr Pt dA SNR SNR  – Radar equation 3 4 L 4 A R Pr where: N – SNR P 120W 50.8dBm t 1 2 G2  Pt dA – ° precision 3 2.263cm 16.5dB kBT 4 L A R4 L 3.5dB (insturment loss) 2 2  P true 1 1 1 1 Kp  1  1  P true Neff SNR true Nnoise SNR true Kp(dB) 10log 1 KpIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences• Statistics: number of looks (left) number of independent samples (right)IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences SNR distribution U=4m/s U=8m/sIGARSS 2012, Munich, Germany U=16m/s U=24m/s Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Kp distribution (25km) U=4m/s U=8m/sIGARSS 2012, Munich, Germany U=16m/s U=24m/s Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Simulation of wind retrieval• Only °data with precision better than 1.0dB will be used for wind retrieval;• Standard MLE method and NSCAT GMF are used for simulation;• Median filter algorithm for wind direction ambiguity removal• 2 kinds of wind field simulated – Spatially correlated parallel wind field and circular wind field – Random wind field IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote Sensing July 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Parallel and circular wind field (U~[2,24])IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Retrieval performance of parallel wind field U Qe(m/s)-U QRMS(m/s)-U Qe (o)-phi QRMS (o)-phi 4 0.43 0.65 51.5 65.9 6 0.45 0.66 15.9 22.3 8 0.55 0.76 10.9 16.5 10 0.68 0.93 10.1 15.4 12 0.83 1.13 10.2 15.6 14 0.99 1.33 10.3 15.7 16 1.17 1.57 10.8 16.3 18 1.38 1.83 11.3 17.0 20 1.60 2.12 12.1 18.1 22 1.86 2.43 12.9 19.1 24 2.13 2.75 13.4 19.8IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Retrieval performance of circular wind field U Qe(m/s)-U QRMS(m/s)-U Qe (o)-phi QRMS (o)-phi 4 0.44 0.68 39.1 51.9 6 0.46 0.68 15.6 22.3 8 0.55 0.77 10.9 16.6 10 0.69 0.95 10.2 15.7 12 0.86 1.17 10.4 16.0 14 1.02 1.38 10.6 16.3 16 1.22 1.62 11.1 16.9 18 1.44 1.90 11.8 17.8 20 1.68 2.20 12.7 19.0 22 1.93 2.51 13.5 20.0 24 2.19 2.83 14.0 20.7IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences FOM varying with wind speedIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Random wind field• Parallel wind field simulated• Wind speed range: 4~24m/s• Wind direction search interval: 10deg• 25km WVC resolutionIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences U=4m/s U=8m/sIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences U=16m/s U=12m/sIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences U=24m/s U=20m/sIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Wind vector retrieval performance RMS of wind speed RMS of wind direction Input wind speed (m/s) (o) 4 0.7 35.5 6 0.7 22.3 8 0.8 16.6 10 1.0 15.7 12 1.2 16.0 14 1.4 16.3 16 1.6 16.9 18 1.9 17.8 20 2.2 19.0 22 2.5 20.0 24 2.8 20.7IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Retrieval performance Near nadir Far range within footprint Near range within footprint (-100~+100) (>400km) (100~400km)U(m/s) 0 U phi 0 U phi 0 U phi (dB) (m/s) ( ) (dB) (m/s) ( ) (dB) (m/s) ( ) 4 0.89-1.79 0.4 44.1 1.43-3.07 1.1 44.7 0.66-2.07 0.4 31.8 8 0.46-0.66 0.9 24.2 0.51-1.01 1.3 26.9 0.44-0.74 0.6 11.0 12 0.41-0.53 1.2 22.7 0.45-0.63 1.8 26.6 0.41-0.54 0.9 10.4 16 0.40-0.49 2.1 22.7 0.44-0.54 2.2 27.6 0.40-0.49 1.3 11.3 20 0.40-0.48 2.9 24.8 0.43-0.50 2.9 30.1 0.40-0.47 1.8 12.8 24 0.39-0.47 3.8 26.3 0.43-0.48 3.6 32.0 0.39-0.46 2.4 14.1IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Assessment by FOMIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Progresses of CFOSAT/SCAT• 2010.04 PDR of SCAT• 2010.12 Detailed design review• 2011.07 Delivery of electrical models (except antenna subsystem) and satellite electrical performance test – System specifications, interface compatibility confirmed• 2011.11 Delivery of mechanical and thermal models• 2011.12 Satellite mechanical test• 2012.02 Satellite thermal test• 2012.05 RF compatibility test• 2012.07 Onboard full operation mode testIGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences RFC test and SCAT integrated test 160 定标 回波 140 120 Amplitude(dB) 100 80 60 40 -750 -562.5 -375 -187.5 0 187.5 375 562.5 750 Frequency (KHz)IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Summary• Design and performance of CFOSAT SCAT is presented: – When U<4m/s, SCAT/CFOSAT cannot provide useful wind retrieval due to its low SNR; – For U=4~8m/s, SCAT/CFOSAT can provide wind retrieval similar to QSCAT only within swath of 800km; – For U>8m/s, SCAT/CFOSAT can provide better wind retrieval with its designed swath of 1000km, compared with QSCAT; – For U>16m/s, the advantage of SCAT/CFOSAT become obvious, due to its more number of looks.• Development of SCAT on time for the scheduled launch in 2014.IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Further to do…• New quality control for sigma-0 measurement with more number of looks and lower SNR;• Development of retrieval making use of increased number of looks;• Evaluation of rain effect, compared with pencil beam system like QSCAT;• Calibration for rotating fan beam system: – In-orbit antenna pattern calibration; – In-orbit possible azimuth-dependent antenna gain variation due to rotary joint.IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)
    • National Space Science Center Chinese Academy of Sciences Thanks for your attentions!IGARSS 2012, Munich, Germany Key Laboratory of Microwave Remote SensingJuly 22-27, 2012 Chinese Academy of Sciences (MiRS, CAS)