Navy GPS

GPS Users Conference02 November 2000

LCDR Drew WilliamsSSC-SD, Code D315

GPS Division

GPS Vulnerability

Navy GPS

SATELLITES PROVIDERF SIGNAL

USER EQUIPMENT COMPUTESPOSITION, VELOCITY AND TIME

UPLINK/DOWNLINK

CONTROL SEGMENT PROVIDES SATELLITE EPHEMERIS, CLOCK SYNCH AND COMMUNICATION INTERFACES

26 SATELLITES ON ORBIT

NAVSTAR Global Positioning System

Navy GPS GPS Position Error

2-D Error

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P(Y)-Code Tracking

L1 C/A-Code Only

Elapsed Time (Hrs:Mins)

Erro

r (M

eter

s)

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Antenna Electronics

NAVSTARGPS

SATELLITE

GPS Receiver

Antenna

Position

Velocity

Time

Antenna System

Navy GPS

The TOP 3 Reasons for GPS Vulnerability:

#1 REASON: Signal Interference– Threat– Blue-on-Blue– Unintentional/Foreign Frequency Allocations

Vulnerability Issues

#3 REASON: Growing Dependency on GPS

#2 REASON: C/A-Code Signal Spoofing

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#1 REASON

POWER RANGE ACCURACY

ARC-182/210 20 W 300 NM N/a

JTIDS/MIDS 200 W 300 NM 30-90 Meters

GPS 60 W 10,980 NM 8 Meters

•Received Power at Earth’s Surface:

0.0000000000000001 Watts (10-16 W)Signal below Thermal Noise Threshold by 15 dBW

Navy GPS

NKC-135 at 10,000 ft. Target at Ground Level Power: 400W

Location: Fort Bragg, N.C.

•Green Civil Receivers Affected•Yellow Civil Receivers Denied•Red Military Receivers

Affected•Purple Military Receivers

Denied

JTFX 98-1 Affected Target Areas

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1227.6 Mhz

L2 L1

P(Y)P(Y)C/AC/A

P(Y)P(Y)

Present Signal Structure

#2 REASON

1575.42 Mhz

•Must Acquire P(Y) Code through C/A Code First•C/A & P Codes are Published in Open Literature, Worldwide

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GPS Jamming Environment

J/S(dB)

0102030405060708090

100110120

1 10 100 1000

P-code tracking

1W

1 kW10 kW100 kW

Range NM

Enhanced Acquisition Goal

Enhanced Tracking Goal

Direct Y Acquisition

C/A-Code Acquisition

Navy GPS

The “Take Away”

REASON #1: -Low power signal can be easily jammed when acquiring GPS

REASON #2: -Military GPS receivers are Spoof Resistant once tracking Y-Code

REASON #3:-Do NOT become a GPS cripple

ALWAYS OPERATE IN THE “KEYED” MODE!

Navy GPS

1 Watt GPS Jammer

Navy GPS

Questions?