GPS receiver autonomous interference detection

Interference presents a challenge in the use of GPS for an aircraft high precision approach, by posing a threat to the accuracy and integrity of the GPS navigation solution. Such interference may result from 'unintentional' sources (such as TV/FM harmonics, radar, MSS), or may result from hostile (jamming) efforts. This research focuses on algorithms for on-board interference detection and monitoring. Types of interference considered include coherent CW and broadband, pulsed and continuous. We study the effects of different types of interference on GPS receiver measurements. From simulation and bench test validation we present interference detection algorithms based on the observable effects of the various types of interference on the GPS receiver derived measurements. Interference detection is based on a combination of the following: test statistic-correlator output power, variance of correlator output power, carrier phase vacillation, and AGC control loop gain. The role and benefits of pseudolites in reducing the adverse effects of interference are also discussed.