the effects of jamming on gps-gnss signals

7/28/2019 The Effects of Jamming on GPS-GNSS Signals.

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Logan Scott, President, LS [email protected]

6 February 2013 Logan Scott / LS Consulting 1

Sponsored By:


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Rohde & SchwarzThe expert in

test and measurement,broadcasting,secure communications,radiomonitoring and radiolocation


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Company profile and GNSS expertise | 3

Company overview

l HistoryEstablished 1933 in Munich, Germany

l Type of enterpriseIndependent family-owned company

l Global presenceIn over 70 countries, approx. 60 subsidiaries

l Net revenueEUR 1.8 billion (FY 11/12, July through June)

l Export shareApprox. 90 percent

l Employees8700 worldwide, with approx. 5600 in Germany

l SuccessA leading international supplier in all of its business fields


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Business fields

Test and measurement

Broadcasting

Secure

communications

Radiomonitoring and

radiolocation

Services

All business fields

contribute to the

aerospace and

defense sector


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Simulating GNSS scenarios

l GPS(C/A and P code), Glonass and Galileo

l Up to 24 satellites for hybrid scenarios and multipathsimulation

l Static and moving receiver simulation with predefined

trajectories and HIL for realtime movement definition

l Simulation of real-world scenarios, including

l Ionospheric and tropospheric effectsl Obscuration and automatic multipath through vertical obstacles

(rural, suburban, urban canyons, etc.)

l Antenna pattern / body mask for cars, aeronautical and military

vehicles/objects plus antenna characteristics

l Spinning and attitude for A&D applications

l General purpose vector signal generatorsupporting many other standards

Features in italics coming soon

R&SSMBV100A

vector signal generator

with GNSS options


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Detection and location of GPS/GNSS interferers

l Detect and find interference

l R&SPR100 portable

receiver

l Manual direction findingTriangulation on a map as option

l Locate interference quickly and precisely

l R&SDDF007 portable direction finderAutomatic direction finding with compact DDF

antennas; car-mobile or stationary

l R&SRAMON mobile locatorAutomatic PC homing software for the

R&SDDF007


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For details, see www.rohde-schwarz.com


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Logan Scott, President, LS [email protected]


Sponsored By:


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GPS Jamming and Spoofing (Military)

Denial of Navigation to Opposing Forces

Create Confusion / Lessen Effectiveness

GPS Jamming and Spoofing (Civil)

Accidental Deliberate

Financial Exploit (More Likely Reason)

Terroristic Exploit (Less Likely Reason)



10/626 February 2013 Logan Scott / LS Consulting 10

Jammings Objective Denial of Navigation Service by Masking GPS Signals

With Noise

Tends Towards Area Denial

Spoofings Objective Convince You That You Are Somewhere or Sometime

You Are Not Overlaying Real Signals With False Signals

Cyber Attack (Lying) Usually Targets A Specific Victim

Structure Jamming Can Act Like UncontrolledSpoofing


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What are We Trying to Track?




Block IIA/IIR Block IIIlock IIR-M, IIF

III: IIF capabilities & Improved civil signal (L1C)

Increased accuracy (4.8-1.2m)

Navigation surety

Increased A/J power (+20 dB)

IIA / IIR: Basic GPS C/A civil signal (L1C/A)

Std Service, 16-24m SEP

Precise Service, 16m SEP

L1 & L2 P(Y) nav

Modernization

IIR-M: IIA/IIR capabilities & 2nd civil signal (L2C)

New military code

Flex A/J power (+7dB)

IIF: IIR-M capability plus

3rd civil signal (L5)

GPS modernization balances military and civil needs


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?*

Block III will introduce the new L1C signal


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BPSK: Binary Phase Shift KeyingBOC: Binary Offset Carrier



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PropagationDelay

AA/demo_code.m

x

=

x

=


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fch = PN sequence chip rate rate

fc = RF center frequency

PN Code

Generator

fch

Sin(2pfct)

BPSK ModulatorPN(t)

spreading sequence

D(t)

data(Only on Data Channel)


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fsqu = subcarrier frequency = square wave frequency

fch = PN sequence chip rate rate

fc = RF center frequency

1/fsqu

PN Code

Generator

fch

Sin(2pfct)

BPSK Modulator

squ(t)

PN(t)

D(t)

data

spreading sequence

Only on Data Channel


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From: Holmes and Dafish Matched Filter Mean Acquisition Time Performance For P(Y), BOC(10,5), and MAN(10)

Codes With FFT Aiding and Noncoherent Combining ION 57th Annual Meeting/CIGTF 20th Biennial Guidance

Test Symposium, 11-13 June 2001, Albuquerque, NM

x

=


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f0 = 10,230,000 Hz

f1 = f0/10 = 1,023,000 Hz

fsqu = m * f1fch = n * f1

M-code is BOC(10,5) fsqu = 10 * f1 = 10,230,000 Hz

fch = 5 * f1 = 5,115,000 Hz

P(Y)-code is BPSK(10)

fch = 10 * f1 = 10,230,000 Hz

C/A-code is BPSK(1)

fch = 1 * f1 = 1,023,000 Hz

L1 Center Frequency

fc = 154 * f0 =1575.42 MHz

L2 Center Frequency

fc = 120 * f0 =1227.60 MHz

L5 Center Frequency

fc = 115 * f0 =1176.45 MHz


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M-Code

P(Y)-Code

L1C*

C/A-Code

*L1C also has a BOC(6,1) Component (Not Shown)


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Signal Format Table.xlsx

Signal Availability

Spectral

Format

First Supporting

Satellite

Generation

Current Number of

Satellites

Transmitting This

Signal

L1 C/A Civil BPSK(1) All 32

L1C Civil BOC(1,1) III 0

L1 P(Y) Military BPSK(10) All 32

L1 M Military BOC(10,5) IIR-M 10

L2C Civil BPSK(1) IIR-M 10L2 P(Y) Military * BPSK(10) All 32

L2 M Military BOC(10,5) IIR-M 10

L5 Civil BPSK(10) IIF 3

L1C also has a BOC(6,1) Component / * L2Y is used in some civil applications


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BPSK Spectral Properties

Equivalent Noise Bandwidth fch

2

sin

)(

f

ff

ffSch

chBPSKp

p


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2

2

cos

sin2

sin

)(

squ

chsqu

chBOC

f

ff

ff

ff

ffSp

p

pp

BOC Spectral Properties (fsqu = k fch)

Equivalent Noise Bandwidth 2.0 fch for fsqu > 2fchEquivalent Noise Bandwidth 1.6 fch for fsqu = fch


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GPS Signal Type(s) Used Signal Spectrum L1 C/A has Structure Vulnerabilities

Jamming Type / Spectrum Radio Propagation Factors

Jamming Mitigation Factors External Sensor Aiding Configuration

Loose vs. Tight vs. Ultratight Coupling Antenna Patterns & Adaptation Performance Frequency and/or Time Domain Excision Backups/Alternative Signals


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Brute Force Jamming

Noise Broadband unstructured

signal intended to

swamp the receiver Spectrum matched

jammer is most effective

CW A constant tone (typically

at or near L1) intended toforce loss of lock ondesired signal

Smart/intelligent Jamming*

Pulsed Noise or Pulsed CW Jammer achieves higher peak power for same

average power; keeps receiver off-balance Attacks AGC, tracking loops & data reading

Swept Tone (against L1 C/A) Captures carrier loop; pulls it off-center Can capture all receiver channels regardless of

Doppler; can exploit C/A code spectral lines

Gold Code (against L1 C/A) Takes Advantage of Gold Code Crosscorrelation

Properties

*Methods to jam more efficiently with same average power constraint.


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PN Code

Generator Sin(2pfct)

Satellite

PN(t)

D(t)

data

PN Code

GeneratorReceiver

PN(t-t)D(t)

data

50 Hz

BPF

Sin(2pfct)

Jammer

2

1

3

4

5


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1


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2


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3

Jammer PSD

Signal PSD


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4

Jammer PSD

Signal PSD


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5

Jammer PSD

50 Hz


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P-Code C/A Code

Signal Chipping Rate (Hz) 10,230,000 1,023,000

Equivalent Noise Bandwidth (Hz) 10,230,000 1,023,000

Post Code Mixing CW Jammer Bandwidth (Hz) 10,230,000 1,023,000

Data Filter Bandwidth (Hz) 50 50

Fraction of Jammer Energy That Gets Through

Data Filter 50 / 10,230,000 50 / 1,023,000

= =

1 / 204,600 1 / 20,460

How Much Stronger Jammer Has To Be Relative

to Signal to Yield Equal Post Correlation Power 204,600 20,460Required Post Correlation Ratio of Signal

Strength to Jammer Strength Needed to Track 10 10

How Much Stronger Jammer Can Be Relative to

Signal And Can Track (J/S numeric) 20,460 2,046

J/S (dB) = 10 log10 (J/S numeric) 43.1 33.1

ProcessingGain


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C/A CodeTemporalSidelobes


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C/A Code RepeatsItself with 1 msec

Period So Lines are 1kHz Apart


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Logan Scott / LS Consulting 40

PRN 3 Response

acq/stage1i.m

6 February 2013

TrackingLoops CanLock on To

These


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Affects Only C/A code Reception Can Adversely Affect Military Receiver Signal Acquisition

Autocorrelation Value Probability

0 dB wrt peak-23.9 dB wrt peak

-24.2 dB wrt peak

-60.2 dB wrt peak

0.098 %12.5%

12.5%

75%

C/A Code Periodic Autocorrelation Values (Integer Code Phase Offsets)

C/A Code Periodic Cross-Correlation Values (Integer Code Phase Offsets)

Cross CorrelationValue

Probability

-23.9 dB wrt peak

-24.2 dB wrt peak

-60.2 dB wrt peak

12.5%

12.5%

75%


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PRN 3 Response

acq/stage1i.m

6 February 2013

TrackingLoops CanLock on To

These


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PRN 3 Response PRN 3 Response

PRN 3 Response PRN 3 Response

No Jamming Gaussian Jamming

CW Jamming PRN1 Jamming


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PRN 3 Response

No Jamming

PRN 3 Response

PRN1 Jamming (J/S=24)

PRN 3 Response

PRN1 Jamming (J/S=24)

PRN 3 Response

No Jamming

L1C/A

L1C


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PRN 3 Response

acq/stage1i.m

6 February 2013

L1COOverlayCode will Make

False PeaksEphemeral; YouWont Lock onto

Them

Can Still BeJammed


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Accounting for Signal And Interference Spectral Shapes



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M-Code

P(Y)-Code

L1C*

C/A-Code



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After: John W. Betz, Effect of Narrowband Interference on GPS Code TrackingAccuracy, presented at ION NTM 2000, 26-28 January 2000, Anaheim, CA

2/

2/

2/

2/

0

2/

2/

0

)()()(

)(

r

r

r

r

r

r

dffGfGCdffGN

dffGC

IN

C

N

C

stts

ss

effective

I Use NumericalIntegration to Evaluate

This Equation


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DensitySpectralPowerNoiseThermal:N

PowerJammerReceived:

1)(

SpectrumPowerNormalizedsJammer':)(

PowerSignalReceived:

1)(

SpectrumPowerNormalizedsSignal':)(

0

t

t

t

s

s

s

C

dffG

fG

C

dffG

fG

C/NonumericN

C

(Hz)BandwidthFilterEndFront

(sec)SeparationEarly/Late

(sec)timenintegratioonpredetectiT

(Hz)bandwidthloopcodeB

o

r

L


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Incident J /SP

(dB wrt S=-160.5 dBW)

EffectiveC/N0

(dB

-Hz)

All Cases:Tant.

=130K, NF=2 dB, L=1 dB,

Gsig

=0dBiC, Gjam

=0dBiC ,24 MHz Passband

M-code

P(Y)-code

C/A-code

Assuming NoReceiver

Saturation!


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M-Code

P(Y)-Code

L1C*

C/A-Code



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Incident J /SP


EffectiveC/N0

(dB

-Hz)

All Cases:Tant.

=130K, NF=2 dB, L=1 dB,

Gsig

=0dBiC, Gjam


M-code

P(Y)-code


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Incident J /SP


EffectiveC/N0

(dB

-Hz)

All Cases:Tant.

=130K, NF=2 dB, L=1 dB

Gsig

=0dBiC, Gjam


M-code

C/A-code

P-code


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The Role of Propagation and Jamming Type



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Appropriate under Line Of SightConditions (1st Fresnel Zone) Rarely Appropriate in Ground Mobile Analysis

Sreceived = Stransmitted + Gt + Gr + 20 log10(/4R)

where:

Sreceived is received signal power (dBW)

Stransmitted is transmitted signal power (dBW)

Gt is transmitter antenna gain in the direction of the receiver (dBiC)

Gr is receiver antenna gain in the direction of the transmitter (dBiC)

is the signals wavelength (19 cm @ L1, 24 cm @ L2)

R is spatial Tx/Rx separation in same units as wavelength


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0

10

20

30

40

50

60

70

80

90

100

1 10 100 1000

Range (km)

J/S (dB wrt -133

dBm Signal)

1000 Watt EIRP

100 Watt EIRP

10 Watt EIRP

1 Watt EIRP

Nominal Unaided P-code

Receiver J/S Threshold


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C/A Code Signal

M Code Signal

P(Y) Code Signal

28 dB-Hz

NominalPhaselockThreshold


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Reflected Path Can Add to Direct Path Either Destructively or ConstructivelyDepending on Geometry

At Longer Ranges, Signal Strength Falls Off at R4 Rate

Can Also Apply In Ground Jammer to Airborne Receiver Cases

Ground

DirectPath

ReflectionPath

Transmitter

Receiver

Two Ray Propagation Model


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fresnel3.m

Two RayModel


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Hata/Okumura Empirical Signal Strength Models

Modified Models Are Described In ETSI GSM 03.30

Considers Six Types of Area:

Large City Open Area Large City Suburban

Large City Urban

Small City Open Area

Small City Suburban

Small City Urban

Mission Planning Tools Such as GIANT (GPS Interference And NavigationTool) Can Accurately Model Jamming Coverage

Includes Topographic Data Base

Can Model Combined Multiple Jammer Effectiveness


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100

101

102

-20

0

20

40

60

80

100

Range (km)

M

edianJ/S(dBwrt-1

60dB

W)

1000 Watt EIRP Jammer at 100 feet AGL, Receiver at 5 feet AGL

free space

Hata Urban

Hata Suburban

Hata Rural Quasi-Open

Hata Rural Open

Nominal Unaided P-codeReceiver J/S Threshold


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Part II: Jamming & Spoofing Mitigations for Military and CivilGPS/GNSS Jamming has long been of concern to military users and recently, has

also become a concern for civil users. This webinar first provides anoverview of classic military mitigations against interference including

robust front end design, adaptive arrays, inertially aided tracking, andother techniques. The current civil jamming environment is thendescribed and the prospects for applying classic techniques to civilusers are examined. An overview of spoofing and jamming detectionmethods is also included and it is argued that civil user equipmentsshould maintain situational awareness.

Wednesday, March 6, 2013

Registration at:http://www.microwavejournal.com/Webinar_6mar13

Sponsored By:
http://www.microwavejournal.com/Webinar_6mar13http://www.microwavejournal.com/Webinar_6mar13http://www.microwavejournal.com/Webinar_6mar13

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