space reflecto 2013

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SPACE REFLECTO 2013 | 5.11.2013

SPACE REFLECTO 2013

Reflectometry applications with theSX-NSR software receiver

Jürgen Dampf, Nico Falk, Thomas Pany, Bernhard Riedl, Jón Winkel

IFEN GmbH

Place: Telecom Bretagne – Brest campus

Date: Nov. 5th, 2013

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Overview

What we need for a Reflectometry System

ExamplesAltimetry

Indoor Channel sounding

How to use the SX-NSR for Reflectometry

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Reflectometry

Current research done mostly with GPS C/A and eventually L2C

Modernized GPS/Galileo signal to add higher bandwidth signalsMore resolution in code phase

Better modeling input, better altimetry

GLONASS and BeiDou to improve availability of suitable reflected signals

Multi-frequency: improved redundancy and accuracy

IFEN SX-NSR-R Software receiver based reflectometry system

for all civil GNSS signals and all frequencies

Measurement of reflected GNSS signals with respect to the line-of-sight signal

Correlator values

Code delay, Doppler, phase, power

Direct (geometric) and indirect (model based) analysis

Ground based, airborne, satellite borne

Solution

Future

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General Setup

MasterTracking channel

SlaveTracking channel

Sync.Sync. Code, carrier NCOCode, carrier NCO

Pseudorange, Doppler, phasePseudorange, Doppler, phasePseudorange, Doppler, phasePseudorange, Doppler, phase

Multi-correlator valuesMulti-correlator values

USBUSB

USB USB

PC running SX-NSRPC running SX-NSRNavPortFront-endsNavPortFront-ends

Master antenna

Measurement antenna

Altimetry Indoor Channel Sounding

Master Antenna Direct LOS (RHCP) Outdoor

Measurement Antenna Reflected Signals (LHCP) Indoor

RF s

witc

h

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Prerequisites – Frontend SyncFrontend synchronization

Code: ADC sampling within +/- 14 cm Remaining difference measured internally by NavPort to +/- 2 cm

Carrier: +/- 180°

Sync. stable during runtime but slightlytemperature dependent (a few millimeter)

Antennas, LNAs, Cable, Mixer introduce code and carrier delaysFor experiment: identical antennas and cables have been used

Delays are temperature dependent

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Prerequisites – CalibrationCalibration for code and carrier phase

Signal from same sourceUpper RHCP antenna

Performed at beginning and endDone by hand

Can be done automatically

To see system delay behavior

Proofed by analyzing calibration sequencesThe estimated height should be zero

Delay model up to 6th order

0 500 1000 1500 2000 2500 3000 3500 4000-4

-2

0

2

4

time in [s]

carr

ier

phas

e di

ff

0 500 1000 1500 2000 2500 3000 3500 4000-2

-1.5

-1

-0.5

0

time in [s]

unw

rapp

ed c

arr

phas

e di

ff

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Signal Tracking3 user selectable tracking modes

Conventional tracking

PVT based Vector tracking

Synchronized Master/Slave tracking

NCOSin/cos

PRNcode

x xIF samples Sum

DLL/FLL/PLL1

Code phase, Doppler 2

3

Vector tracking

Channel slaving

Code, Freq., Carr.Discriminators

NCO basedpseudoranges

+ PolyfitHigh-rate rangesCode, carr. Pseudorange

Doppler

PVT

Master channel

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Altimetry

Altimetry

Surface stateSoil moisture, salinity

Wind speed/direction

Surface cover (ice, ...)

Galileo E5 AltBOC Code-AltimetryLake south of Graz

Wave height: 0-1 cm

Antenna height: 441 cm

No calibration

Galileo PRN 11

water wood

mixed surfaces

Carrier Phase AltimetryLake south of Graz for both Measurements

Antenna height: 271 cm

Wave height: 0-1 cm

Calibration: 15 – 30 – 5 min

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Galileo E5 AltBOC Code-Altimetry ResultsCoherently slaved multicorrelator

Provides Doppler/delay mapsCoherent integration time 0.02*2^7=2.56 s

cm-level code noise

Flat surface of the lake

2nd order polynomial fit to obtain peak position

0 100 200 300 400 500 600 7003.8

4

4.2

4.4

4.6

4.8

5

5.2

5.4

Time [s]

Est

. he

ight

[m

]

Inst. estMeanTruth

AltBOC Correlation FunctionAltBOC Correlation Function

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Single Frequency Carrier Phase ResultsGalileo E5b pilot of Measurement 1

CalibrationCalibration: 15 – 30 – 5 min

Estimated / True Height272.62 cm / 271,00 cm

Offset: 1.62 cm

0 500 1000 1500 2000 2500 3000 3500 4000-1

0

1

2Carrier phase altimetry of channel 2

time in [s]

carr

ier

phas

e di

ff.

[m]

unwrapped carrier phase diff.

sequence 1sequence 2

sequence 3

50 100 150 200 250 300-0.07

-0.06

-0.05

-0.04Unwrapped carrier phase diff. of sequence 1

time in [s]

carr

ier

phas

e di

ff.

[m]

sequence 1

ant. height from model: -1.1475e-05 m

500 1000 1500 2000 2500 3000

0.6

0.8

1

1.2

1.4

1.6

1.8

Unwrapped carrier phase diff. of sequence 2

time in [s]

carr

ier

phas

e di

ff.

[m]

sequence 2

ant. height from model: 2.7262 m

3350 3400 3450 3500 3550 36000.9

0.905

0.91

0.915

0.92

0.925

Unwrapped carrier phase diff. of sequence 3

time in [s]

carr

ier

phas

e di

ff.

[m]

sequence 3

ant. height from model: -0.077307 m

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Dual Frequency Carrier Phase ResultsGalileo E1 and E5b pilot of Measurement 1

Legend:Blue: Carrier phase differences

Black: Varied integer ambiguities

Red: Sing. Freq. integer ambiguity

Green: Dual Freq. integer ambiguity

Estimated / True Height271,83 cm / 271,00 cm

Offset: 8,3 mm

500 1000 1500 2000 2500 3000-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

time [s]

unw

rapp

ed p

ahse

diff

[m

]

E1

500 1000 1500 2000 2500 3000

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

time [s]

unw

rapp

ed p

ahse

diff

[m

]

E5b

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Water Wave AnalysisEffect of water waves on the carrier phase difference of E5b pilot

True wave height: 3-6 cm

True wave frequency: 1-2 waves/sec

Amplitude of carrier phase difference: 3-4 cm

Estimated wave frequency: 1,5 waves/sec

2579 2579.5 2580 2580.5 2581 2581.5 2582 2582.5 2583

-0.32

-0.315

-0.31

-0.305

-0.3

-0.295

-0.29

-0.285

Carrier phase altimetry of channel 2

time in [s]

carr

ier

phas

e di

ff.

[m]

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Indoor Channel Sounding ISetup

Outdoor antenna (e.g. Rooftop)

Static indoor antenna

Each antenna connected to one dedicated front-end

Front-ends sync‘ed

Correlation functions, 5x 1s integration timeGPS PRN27 GPS PRN252nd floor

1 (Window)

Observatory Lustbühel, Graz/Austria

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Indoor Channel Sounding II

Correlation functions, 5x 20s integration timeGPS PRN27 Galileo PRN20

Correlation functions, 5x 20s integration timeGPS PRN27 GPS PRN2

1st floor

2nd floor 2

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SX-NSR for Reflectometry I

RF Front-End4 RF bands up to 15 MHz simultaneously

GPS L1, L2P, L2C, L5

Galileo E1, E5a, E5b, E5a+b (AltBOC), E6

SBAS L1, L5

GLONASS G1, G2

Beidou B1, B2, B3

User specific ≤ 2.5 GHz

Frontend coupling for 8 RF bands

Dual antenna operation

1 x high-speed USB2.0

Interfaces to IMU, PPS, clock, baro., …

20.48 or 40.96 MHz sample rate

2-bit, 4-bit or 8-bit sampling

Signal Processing SoftwareUltra high sensitivity19 dBHz acquisition10 dBHz tracking

~20-30 channels per CPU core (real-time)

GNSS baseband processing (acquisition and tracking) for all civil GNSS signals plus GPS L2P

Sensor data synchronization and processing

Position computation with RAIM

Standard interfaces(RINEX, NMEA, SP3(c), …)

Scientific ASCII log files output

C API

Windows PC, 2GB RAM, SSSE3 capable processor

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SX-NSR for Reflectometry IIIF samples recording

Prototyping

SX-NSR MATLAB

Code phase AltimetryCarrier phase Altimetry

Dump Logs

RawLog

Params

filter valid correlator

data

Sync. via GPS/Galileo

Time

filter necessary

data

Find correlation

peaks

Calc. Carrier phase diff.

2nd Order Polyfit

Unwrap Raw Phase

Calc. Code phase diff.

Unslip (Cycle Slips)

Define sequences

Define sequences

Apply code altim. model

Apply carrier altim. model

Antenna height

Antenna height

System code

calibration

System carr.

calibration

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SX-NSR for Reflectometry IIIIntegration into SX-NSR using it‘s APIsStarting pointMatlab prototype code

TaskTranslate to native SX-NSRcode usingBaseband and Navigation API

GoalFully operational, real-time capable Reflectometry System

SX-NSR

SampleProvider

PVT Solution

USB IF

API 1

Signal manipulation or injection

API 2

Baseband(Acquisition and Tracking)

WiFi Scanning

API 3

Navigation(Positioning)

API 5

Sensor

API 4

API 6

Utility API(Text output,access to config settings,access to internal data structures, Data Transfer Gateway)

File Input

API 2 (Baseband)

Acquisition

Rinex, NMEA, various

dump logs

Datastream Merger

(IF + WiFi Data)

API 2 (Baseband)

Tracking

API 2

Baseband(Acquisition and Tracking)

Assistance(External Data)

Receiver Processing

user supplied

Internal NSR functions

IF +Sensor Data Recording

NSR DLL

init

process

close

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ConclusionSX-NSR is the right tool for prototyping Reflectometry systems

Sync‘ed front-ends

Use all civil GNSS signals

Freely definable Multicorrelators

Use our Matlab Toolbox

It is also the right tool for operational useAPI for user implementations

Real-time capability

Data recorder for true repeatabilityTest different algorithms

Change settings

Run the same IF samples again

Possible applicationsRemote Sensing (Altimetry, surface state, ...)

Indoor Channel-Sounding

Bistatic Synthetic Aperture Radar (=passive Radar based on GNSS illumination)

More information and contact: www.ifen.com

space reflecto 2013

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