Alternate Navigation Plan: Terrestrial Beacons

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Alternate Navigation PlanTerrestrial Beacons

• Peter Dolton and Sam Hatch
• Project Advisor LT Rothberg CAPT Hartnett
• Sponsor USCGA ECE Section

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Outline

• Vulnerabilities GPS
• LORAN-C and DGPS as alternate
• Signal Propagation interference

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Vulnerabilities of GPS
Background

• 2001 Study by Department of Transportation
• Current research by 1/c Ellsworth

Boat from James Bond Tomorrow Never Dies.
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Horizontal Dilution of Position Problem(HDOP)
Background

• LORAN-C/differential (20/10-m accuracy)

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From Integrated 100-300kHz Ranging System v4
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USCGA Electrical Computer Engineering
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DGPS as Supplement
Objectives

• Selection Criteria
• Standardized message format
• National Coverage

• DGPS Signal
• USCG regulated sites
• Coastal and Inland Coverage
• Long planned life-cycle

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Complications of DGPS
Objectives

• Long Range Signal degradation and corruption
• System Timing Standard
• Independent of GPS
• Accurate
• Cesium based clocks C2CEN

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Skywave Range Possibilities
Technical Approach

• Previous studies
• Antenna Modeling
• Nation Highways Administration
• Inland tests
• Current work
• Test Mathematical model
• Investigate ocean phenomenon

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Desired End Product
Technical Approach

• Multiband Receiver
• Software Based
• DGPS and Loran reference stations (LFMF)
• GPS Independence
• Alternative Timing Standard
• Accurate positioning by terrestrial based systems

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Conclusions

• GPS is vulnerable to jamming
• LORAN-C and DGPS system
• Skywave propagation interference

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Future Work

• Installed on CG cutters
• Reliable for altitude

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Questions?