GPS Users Conference 02 November 2000

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GPS Users Conference02 November 2000
GPS Vulnerability

• LCDR Drew Williams
• SSC-SD, Code D315
• GPS Division

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NAVSTAR Global Positioning System
SATELLITES PROVIDE RF SIGNAL
UPLINK/DOWNLINK
26 SATELLITES ON ORBIT
USER EQUIPMENT COMPUTES POSITION, VELOCITY AND
TIME
CONTROL SEGMENT PROVIDES
SATELLITE EPHEMERIS, CLOCK SYNCH AND
COMMUNICATION INTERFACES
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GPS Position Error
Error (Meters)
Elapsed Time (HrsMins)
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NAVSTAR GPS SATELLITE
Antenna System
Antenna
Antenna Electronics
Position Velocity Time
GPS Receiver
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Vulnerability Issues
The TOP 3 Reasons for GPS Vulnerability

• 1 REASON Signal Interference
• Threat
• Blue-on-Blue
• Unintentional/Foreign Frequency Allocations

2 REASON C/A-Code Signal Spoofing
3 REASON Growing Dependency on GPS
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1 REASON

• Received Power at Earths Surface
• 0.0000000000000001 Watts (10-16 W)
• Signal below Thermal Noise Threshold by 15 dBW

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JTFX 98-1 Affected Target Areas

• 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

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2 REASON
Present Signal Structure
L2
L1
C/A
P(Y)
P(Y)
1227.6 Mhz
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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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!

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1 Watt GPS Jammer
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Questions?