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FR2_T04_1_PAU_INTA_MicroSat_A_Camps.pdf

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FR2_T04_1_PAU_INTA_MicroSat_A_Camps.pdf

  1. 1. PAU INSTRUMENT ABOARD INTA MICROSAT-1: A GNSS-R DEMONSTRATION MISSION FOR SEA STATE CORRECTION IN L-BAND RADIOMETRY A. Camps1, J.F. Marchán1,5, E. Valencia1, I. Ramos1, X. Bosch-Lluis1, N. Rodriguez1, H. Park1, A. Alcayde2, S. Chavero2, P. Martínez2, A. Mollfulleda2, J. Galindo2, M. Angulo3, and A. Rius4 1Dept.of Signal Theory and Communications, Universitat Politècnica de Catalunya and IEEC CRAE/UPC, UPC Campus Nord, D4-016, 08034 Barcelona, Spain. E-mail: camps@tsc.upc.edu 2ADTelecom, Camí de la Pelleria, 12, P.I. Bonavista, 08915 Badalona, Spain 3INTA, Dept. Progrs. Espaciales y Ciencias del Espacio, Torrejón de Ardoz 28850, Madrid, España 4IEEC/ICE-CSIC, Campus UAB/Fac. Ciències, Torre C-5-parell-2a planta, 08193 Bellaterra, Spain 5Institut Cartogràfic de Catalunya, Parc de Montjuïc, 08038 Barcelona, Spain IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 1
  2. 2. Outline of the presentation: 1. Introduction 2. Measurement Concept 3. Instrument Heritage 4. PAU in INTA’s MicroSat-1 5. Preliminary Tests 6. Conclusions IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 2
  3. 3. 1. Introduction • L-band microwave radiometry is the best suited for Sea Surface Salinity and Soil Moisture  e.g.: SMOS, Aquarius, SMAP missions • The brightness temperature of the sea surface depends on: Th ,v  ,SST,SSS  1  h ,v  ,  r f ,SST, SSS    SST  Th ,v  , param  - salinity - physical temperature - sea state (surface roughness) critical correction: . SMOS: aux. data + multi-angular information . AQUARIUS: L-band scatterometer • Potential solution = combination in a single instrument 3 different sensors: - PAU-RAD: New type of radiometer  measure TB - PAU-GNSS/R: GPS reflectometer  measure sea state (and altimetry) - PAU-IR: IR radiometer  measure SST (PAU concept proposed to ESF in 2003, granted in 2004, cont’ MICIIN projects) IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 3
  4. 4. 2. Measurement Concept • GNSS opportunity signals reflected over the sea surface come from a larger area (“glistening zone”) when the sea is rough  longer delays as compared to specular reflection point + larger Doppler shifts • The Delay Doppler Map (DDM) provides an indication of the “widening” of the so-called glistening zone  related to TB  may be used to correct for sea state • Sample DDMs from UK-DMC (Tcoh.= 1 ms; Tincoh. = 200 ms) over the ocean, land and ice IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 4
  5. 5. 3. PAU Instrument Heritage (i) DO-DEREC early tests (July 2002) griPAU ground-based instrument 40 km South of Barcelona (Gran Canaria, 2008 & 2009)  sea state determination and impact on TB • 24x32 DDM points (min =0.09 chips, fd=200 Hz) • Tcoh. min = 1 ms / Tcoh. max = adjustable • Tincoh. min = 1 ms / Tincoh. max = adjustable PAU-ORA (One Receiver Airborne): ALTIMETRIC & SM applications IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 5
  6. 6. 3. PAU Instrument Heritage (ii) TB Sensitivity to Normalized DDM Volume Measured DDM and threshold applied 5 x 10 5 x 10 3 2.5 2 2 [au] 1.5 1 1 2000 1000 2.5 0.5 0 2 1.5 -1000 1 -2000 0.5 Doppler [Hz] Delay [chips] TB Sensitivity to Waveform’s Tail Length IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 6
  7. 7. 4. PAU in INTA’s MicroSat-1 (i): Sponsored by Spanish Ministry of Science and Innovation “Sistemas GNSS-R para Futuras Misiones SMOS: SUBPROYECTO UPC”, code: AYA2008-05906-C02-01/ESP IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 7
  8. 8. 4. PAU in INTA’s MicroSat-1 (ii): Simplified design: • Radiometer operated as a TPR with frequent calibration, • GNSS-Reflectometer operated while receiver is connected to the antenna, • Combination of up-looking and down-looking channels through coupler Frequency plan: • fRF = 1575.42 MHz, fIF = 70 MHz, fs = 16.384 MHz Architecture: • Two cold redundant receivers and processing boards. UP-looking antenna Processing board #1 Processing board #2 DOWN-looking antenna IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 8
  9. 9. 4. PAU in INTA’s MicroSat-1 (iii): Antenna Array Design 1. Antenna array optimized for lowest possible ohmic losses and maximum gain Planar structure (microstrip patches + stripline 8:1 power combiner < 6 mm thick) Patch GPS R4360 f= 1575.42 MHz r = 6.15 l = 36.6 mm h = 2.54 mm S11 = -25 dB G = 5.37 dB  = 86% Array G = 15 dB IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 9
  10. 10. 4. PAU in INTA’s MicroSat-1 (iv): All boards (Engineering Model – final version pending) DPU VOLTAGE MAIN SUPPLY RF BOARD BOARD BOARD IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 10
  11. 11. 4. PAU in INTA’s MicroSat-1 (v): RF/IF chain 2. RF / IF chain to provide G ~ 110 dB gain, NF ~ 2 dB, B ~ 2.2 MHz G [dB] Gcum [dB] IP3 [dB] IP3cum [dB] NF [dB] NFcum [dB] IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 11
  12. 12. 4. PAU in INTA’s MicroSat-1 (vi): DPU 3. Signal Processor • Virtex-4 FPGAs + in-orbit reconfiguration capability • Interfaces: CAN (commands & reconfigurability), Space-Wire (data) • DDM size: 4096* samples in delay x 16 samples in Doppler • “Dummy” processing: Sequential search of all GPS satellites using 1 ms coherent integration time + > 10 incoherent avg. (100 typ.) • On-board NRT processing or raw data acquisition IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 12
  13. 13. 4. PAU in INTA’s MicroSat-1 (vii): DPU Data Processing Unit Main Board (x 2: space-qualified + commercial compts.) CAN interface SRAM ADC IF Input signal Back- PROM panel SpaceWire connector Interface FPGA CLOCK GENERATION IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 13
  14. 14. 4. PAU in INTA’s MicroSat-1 (viii): Boards being stacked IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 14
  15. 15. 4. PAU in INTA’s MicroSat-1 (ix): Boards being stacked IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 15
  16. 16. 5. Preliminary Tests: (i) R&S SMU-200A arbitrary signal generator + GPS module Acquisition Set-up IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 16
  17. 17. 5. Preliminary Tests: (ii) Sampling = 6-bit Level = GPS L1 C/A at ground level Tcoh =1 ms Nincoh =1 fDoppler [Hz] Doppler [lags] Delay [lags] Delay [lags] IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 17
  18. 18. 5. Preliminary Tests: (iii) Sampling = 6-bit Level = GPS L1 C/A at ground level -15 dB Tcoh = 2 ms Nincoh =50 Doppler [lags] Delay [lags] IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 18
  19. 19. 6. Conclusions • PAU in INTA MicroSat-1 is a small secondary payload to test sea state correction in L-band radiometric observations (TB vs Volume under the normalized DDM). • Combination of direct and reflected signals will allow also to “explore” other scatterometric and altimetric measurements • Planar antenna size limited by available space: trade-off between low ohmic losses (~86%), “high” gain (~15 dB), side lobes (-11 dB at 90º), mass and thickness (< 6 mm). • Computes real-time DDMs or stores raw data for ground processing • Engineering Model finished and first tests performed. • Current basic processing scheme: Tcoh = 1 ms, Nincoh. avg = 100 + blind sequential search of GPS satellites in view IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 19
  20. 20. Acknowledgements: Activities sponsored by ESF – EURYI 2004 grant and the Spanish Ministry of Science and Innovation “Sistemas GNSS-R para Futuras Misiones SMOS: SUBPROYECTO UPC”, code: AYA2008-05906-C02-01/ESP IGARSS 2011, Vancouver, Canada, July 25-29, 2011 © UPC, ADTelecom 2011 20

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