Status of the Signals of Opportunity Airborne Demonstrator (SoOp-AD) Purdue University Harris (Formerly Exelis, Inc) Digital Receiver Design Simula'on, Retrieval Algorithms, Requirements Def. PI: Jim Garrison (Assoc. Prof) George Alikakos Yao-Cheng “Zenki” Lin (PhD candidate) Co-I: Steve O’Brien NASA GSFC Langley Research Center Systems Engineering, RF Design, Aircra= Integra'on Aircra= Opera'ons Co-I: Jeff Piepmeier (555) Bruce Fisher Co-I: Joe Knuble (555) Dr. Stephen Katzberg – Consultant Cornelus Du Toit (AS&D) ScaAering Model, Signal Processing Co-I: Alicia Joseph (617) ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 1
SoOp-AD Measurement Overview P-Band Reflectometry Basis of Measurement Expected Performance Parameter SoOp Airborne SoOp Spaceborne Resolution* 100m 870m We plan to measure Root Zone Soil Moisture Antenna Size 75 x 75 cm 75 x 75 cm (RZSM) through cross-correladon of direct and Sensing Depth 0-30cm 0-30cm reflected P-Band geosynchronous Sensing Precision** 0.04m 3 /m 3 0.04m 3 /m 3 communicadon satellite signals. *Specular Reflecdon Assumed **SMAP Requirement ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 2
SoOp-AD Soludon • SoOp-AD will use geostadonary P-Band SATCOM systems – 225-420MHz allocadon for government use, SoOp-AD will focus on 240-270MHz band: 18 x 25-kHz channels, 20 X 5- kHz channels. – Condnuous use by US since 1978, follow-on systems planning legacy support – SoOp-AD method measures correladon of direct and reflected signals - does not require demod / decode of the transmission. ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 3
Comparison to Convendonal Methods • L-Band – L-band (SMAP) penetrates only few cm of soil – Saturadon at L-band limits the ability to sense soil moisture through vegetadon – RZSM from SMAP Level 4 assimiladon product • P-Band Radar – Difficult to find allocadon in heavily udlized spectrum – ESA-BIOMASS cannot operate in North America or Europe due to interference with Space Object Tracking Radar – RFI – Expensive from space ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 4
SoOp-AD Project Highlights IIP Timeline • – Awarded in April ’14. – System I&T at GSFC is underway. – Science flights in Fall of ’16. Instrument • – Antennas: Patch, Dual Linear Pol, Null Steering – Receivers: Standard P-Band Receivers w/ internal calibradon. S-Band receiver for XM Radio included – Digital System: FPGA based. 7TB Storage for raw and/or correladon data – Two aircrap racks: 12U Total Aircrap Campaign • – Flying on NASA Langley B200. – Co-Flying with SLAP instrument (GSFC’s Acdve / Passive L-Band). – Science flights over the St. Joseph’s Watershed . ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 5
Signal Bands and Coverage 5 kHz channels 25 kHz channels 1 0.5 0 240 245 250 255 260 265 270 Frequency (MHz) Incidence Angle for Geostadonary Sources used by SoOp-AD. (Satellite Names) November Oscar Papa Quebec ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 6
Measured Signal Details & RFI SoOp-AD RFI & Source Survey From 12/24/14 11:40EST to 1/3/15 16:40EST Waterfall spectrum measured at GSFC over 11 days. Note persistence of SATCOM signals and broad-band RFI. ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 7
SoOp-AD System Architecture Reflectometry: DIGITAL RECEIVER RF SYSTEM Correlator: < Reflect-V*Reflect-V >*8 Channels Complete 4x4 Matrix Inc. Cross-Pol & Auto-Corr. Direct-V Correlator: < Direct-H*Reflect-V >*8 Channels RF Receiver Channelizer CH8 CH.. CH2 Correlator: < Direct-H*Reflect-H >*8 Channels 400 Complex Terms CH1 TC CH8 t E t S t L t N CH.. TC CH2 CH1 Direct-H Z(0) Z(t E ) Raw Data Mode Z(t S ) Z(t L ) Reflect-H Z(t N ) CH8 CH.. TC CH2 TC TWP CH1 CH8 CH.. TC CH2 Reflect-V To Correlator CH1 ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 8
Spectrum from SoOp-AD Raw Data Mode ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 9
“Auto” Example: (V_Sky, V_Sky*) Corr_1 V_Sky (0 Lag) Digital Complex Correlator tau1 Corr_2 tau2 Corr_3 tau3 Corr_4 tau4 Corr_5 SoOp-AD (IIP-13-0076) Second Annual 6/22/16 10 Review
SoOp-AD Auto-Correlator Verificadon • Correlators have programmable 4 lags + 0 • 300-kHz noise detecdon bandwidth • Test: 0, 1, 2 and 10 us (400 us not shown) 1 Noise only input 0.8 -- theoredcal 0.6 X measured 0.4 0.2 0 0 2 4 6 8 10 Delay 7 s ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 11
“Cross” Example: (V_Sky, V_Gnd*) Corr_1 V_Sky (0 Lag) tauE Corr_2 Mux tauS Corr_3 tauL Corr_4 tauN Mux Corr_5 tauN* Mux V_Gnd tauE* Mux * Negadve Delay SoOp-AD (IIP-13-0076) Second Annual 6/22/16 12 Review
SoOp-AD Cross-Correlator Verificadon • AWG QPSK waveform into V&H inputs 0 delay 22 us delay ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 13
Technology Development: Antennas • Antenna radome design for B200 aircrap Fairing Mount… …and Cover SLAP 14
Technology Development: Antennas P-band antenna design Aperture coupled patch antenna element SoOp-AD (IIP-13-0076) Second Annual 6/22/16 15 Review
Antenna System Consideradons zenith Direct-to-Reflect isoladon is • driving requirement – But not in orbit! Using two-element interferometer • to synthesize a two-element array with null steering in post- processing. Simuladon: Earth View Beam • – Co-pol (blue): LHCP horizon – X-pol (red): RHCP Results simulate a post-processed • pawern with a null steered to +40° ESTF June 14-16, 2016 SoOP-AD an ESTO IIP nadir 16
Technology Development: Antenna Radome • Radome designed and fabricated. • Test-fit Successful. • Awaidng test flight SoOp-AD (IIP-13-0076) Second Annual 6/22/16 17 Review
Next Steps • Ground Tesdng • Aircrap Safety Test • Aircrap Campaign in Fall of 2016 ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 18
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