410A-D: GPS and GNSS RFI & Jamming Concerns

This course provides an overview of the analytical methods, procedures, and policies associated with the spectrum management of the key systems required for safe operation in the national airspace system. The course provides spectrum-related details on GPS, on conventional navigation aids, communication and surveillance systems. The impending widespread proliferation of Ultra Wide Band (UWB) devices is also considered.

Dr. Trent Skidmore
Ohio University

Spectrum Management Fundamentals
• Introduction to spectrum management
• Core mathematical concepts
• Key navigation aids, communication, & surveillance systems
• Specifications, orders, and regulations

GPS Receiver Performance Case Study
• Common receiver configurations
• Broadband and CW Interference effects
• C/N₀ measurements
• Interference and integrity

Impact of Ultra Wide Band Devices (UWB) on Navigation Systems
• Overview of UWB devices
• Impact of UWB on GPS
• Impact of UWB on other NAV & COM systems

Case Study: UWB Effects on Aircraft Navigation and Landing

Level: A basic knowledge of terrestrial and satellite navigation (GPS) systems, as well as some familiarity with engineering analysis methods is assumed. Proceed to 410B-D to complete the series.

1:30 - 5:00, Monday, String 4
410B: GPS and GNSS RFI & Jamming Concerns I

Dr. Stephen Heppe
The Insitu Group

Radio frequency interference (RFI) and jamming are of increasing concern to all users of GPS and GNSS. This course will facilitate an understanding of the threats posed by unintentional RFI, jamming and spoofing for civilian and military users. General threats are identified, jamming strategies are assessed, and receiver countermeasures are identified. New vulnerabilities are identified and solutions are recommended.

Threat Overview and Unintentional RFI
• GPS constellation; signal waveforms, power levels
• Nominal receiver architectures
• Functional impact of RF interference (CW, noise, pulses)
• Performance results
• Scope of problem; required C/N0; RF interference

Jamming and Spoofing Threats
• Jamming and spoofing objectives, analysis
• Receiver performance, break points, countermeasures
• Effects of broad band noise, pulsed noise, CW spectral matching
• Spoofing techniques; pseudorange and Doppler matching
• Jamming/spoofing comparisons: GPS vs. GLONASS
• Effects of jamming/spoofing on DGPS and WAAS

Case Studies
• Terrorist attack
• Land-mobile and maritime issues

Level: Assumes an understanding of GPS and DGPS operation and a familiarity with communication techniques.
Proceed to 410C-D to complete the series.

8:30 - 12:00, Tuesday, String 4
410C: GPS and GNSS
RFI & Jamming Concerns II

This half-day addresses vulnerability analysis and design techniques for mitigating the effects of RFI and jamming within the GPS receiver.

Mr. Phil Ward
Navward Consulting

Overview of RFI Mitigation Techniques
• First principles of RFI mitigation
• Mitigating unintentional RFI
• Mitigating intentional RFI (jamming)

RFI Effects on GNSS Receivers
• Front end considerations
• Impact on AGC
• Impact on A/D converter
• RFI situational awareness
• Mitigating narrowband RFI
• Mitigating wideband RFI

GNSS Receiver Vulnerabilities/Mitigation Approaches
• C/A code vulnerability to CW
• Pre-correlation vs. post-correlation A/D converter vulnerabilities
• SBAS vulnerability
• DGPS vulnerability
• Codeless/semi-codeless receiver vulnerability
• Considerations of natural factors

Please Note: This session is designed to be taken in conjunction with 410D, which follows it, and may not stand alone comprehensively without that additional material.

Level: Assumes an understanding of RFI and jamming concerns, like that provided by 410A & B, as well as a basic understanding of GPS receiver operation. Proceed to 410D.

1:30 - 5:00, Tuesday, String 4
410D: GPS and GNSS RFI & Jamming Concerns III

This half-day builds on 410C addressing inertial integration, adaptive array, and other techniques for mitigating the effects of RFI and jamming.

Mr. Ward

Analysis of RFI Effects I
• Unjammed signal to noise power ratio
• Jamming-to-signal power ratio – J/S

Analysis of RFI Effects II
• Computing receiver tracking threshold
• Receiver tracking threshold effects on J/S
• Receiver tracking threshold effects on Tolerable J

Analysis of RFI Effects III
• Computing range to jammer at threshold
• RFI effects on code tracking
• RFI effects on narrow correlator receivers

Please Note: This session is designed to be taken in conjunction with 410C, which precedes it, and may not stand alone comprehensively without that additional material.

Level: Assumes an understanding of RFI and jamming concerns, like that provided by 410A-C, as well as a basic understanding of GPS receiver operation.