Status of the Signals of Opportunity Airborne Demonstrator (SoOp-AD) - - PowerPoint PPT Presentation

Status of the Signals of Opportunity Airborne Demonstrator (SoOp-AD)

ESTF June 14-16, 2016 SoOP-AD an ESTO IIP 1

Purdue University

Simula'on, Retrieval Algorithms, Requirements Def. PI: Jim Garrison (Assoc. Prof) Yao-Cheng “Zenki” Lin (PhD candidate)

NASA GSFC

Systems Engineering, RF Design, Aircra= Integra'on Co-I: Jeff Piepmeier (555) Co-I: Joe Knuble (555) Cornelus Du Toit (AS&D) Co-I: Alicia Joseph (617)

Harris (Formerly Exelis, Inc)

Digital Receiver Design George Alikakos Co-I: Steve O’Brien

Langley Research Center

Aircra= Opera'ons Bruce Fisher

• Dr. Stephen Katzberg – Consultant

ScaAering Model, Signal Processing

SoOp-AD Measurement Overview

We plan to measure Root Zone Soil Moisture (RZSM) through cross-correladon of direct and reflected P-Band geosynchronous communicadon satellite signals. Expected Performance

Parameter SoOp Airborne SoOp Spaceborne Resolution* 100m 870m Antenna Size 75 x 75 cm 75 x 75 cm Sensing Depth 0-30cm 0-30cm Sensing Precision** 0.04m3/m3 0.04m3/m3

P-Band Reflectometry

*Specular Reflecdon Assumed **SMAP Requirement

Basis of Measurement

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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.

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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

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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.

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Signal Bands and Coverage

240 245 250 255 260 265 270 0.5 1 Frequency (MHz) November Oscar Papa Quebec

5 kHz channels 25 kHz channels

(Satellite Names)

Incidence Angle for Geostadonary Sources used by SoOp-AD.

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Measured Signal Details & RFI

Waterfall spectrum measured at GSFC over 11 days. Note persistence of SATCOM signals and broad-band RFI.

SoOp-AD RFI & Source Survey From 12/24/14 11:40EST to 1/3/15 16:40EST

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SoOp-AD System Architecture

Correlator: < Reflect-V*Reflect-V >*8 Channels Correlator: < Direct-H*Reflect-V >*8 Channels

CH1 CH2 CH8 CH.. CH1 CH2 CH8 CH..

TC

Direct-H Direct-V Reflect-H Reflect-V

TC TC TC TWP TC

tE tS tL

Z(0) Z(tS) Z(tE) Z(tL)

CH1 CH2 CH8 CH..

RF Receiver Channelizer Correlator: < Direct-H*Reflect-H >*8 Channels

tN

Z(tN)

CH1 CH2 CH8 CH..

Complete 4x4 Matrix Inc. Cross-Pol & Auto-Corr. 400 Complex Terms

To Correlator

RF SYSTEM DIGITAL RECEIVER

Raw Data Mode

Reflectometry:

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Spectrum from SoOp-AD Raw Data Mode

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“Auto” Example: (V_Sky, V_Sky*)

6/22/16 SoOp-AD (IIP-13-0076) Second Annual Review 10

V_Sky Corr_5 Corr_4 Corr_3 Corr_2 Corr_1 (0 Lag) tau1 tau2 tau3 tau4

Digital Complex Correlator

SoOp-AD Auto-Correlator Verificadon

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• Correlators have programmable 4 lags + 0
• 300-kHz noise detecdon bandwidth
• Test: 0, 1, 2 and 10 us (400 us not shown)

Delay 7s

2 4 6 8 10 0.2 0.4 0.6 0.8 1

Noise only input

• - theoredcal

X measured

“Cross” Example: (V_Sky, V_Gnd*)

6/22/16 SoOp-AD (IIP-13-0076) Second Annual Review 12

V_Sky V_Gnd Corr_5 Corr_4 Corr_3 Corr_2 Corr_1 (0 Lag) tauE Mux tauS tauL tauE*

* Negadve Delay

Mux tauN* Mux tauN Mux

SoOp-AD Cross-Correlator Verificadon

• AWG QPSK waveform into V&H inputs

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0 delay 22 us delay

Technology Development: Antennas

14 SLAP

• Antenna radome design for B200 aircrap

Fairing Mount… …and Cover

Technology Development: Antennas

P-band antenna design

Aperture coupled patch antenna element

6/22/16 SoOp-AD (IIP-13-0076) Second Annual Review 15

Antenna System Consideradons

• Direct-to-Reflect isoladon is

driving requirement – But not in

• rbit!
• Using two-element interferometer

to synthesize a two-element array with null steering in post- processing.

• Simuladon: Earth View Beam

– Co-pol (blue): LHCP – X-pol (red): RHCP

• Results simulate a post-processed

pawern with a null steered to +40°

horizon nadir zenith

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Technology Development: Antenna Radome

• Radome designed and fabricated.
• Test-fit Successful.
• Awaidng test flight

6/22/16 SoOp-AD (IIP-13-0076) Second Annual Review 17

Next Steps

• Ground Tesdng
• Aircrap Safety Test
• Aircrap Campaign in Fall of 2016

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