Passive interference localization within the GNSS environmental monitoring system (GEMS): TDOA aspects

Due to their low power levels, global positioning system (GPS) signals are very susceptible to interference from intentional and unintentional sources. With ever increasing reliance on global navigation satellite systems (GNSS) for everyday operation of safety–critical infrastructure, the detection, localization and elimination of interference to GNSS is of paramount importance. The GNSS environmental monitoring system (GEMS) II provides the capability to detect and localize interferers in real time in a given area. It consists of a number of spatially distributed sensor nodes connected to a central processing unit. Interference is localized using hybrid direction-of-arrival (DOA) and time-difference-of-arrival (TDOA) techniques. We describe the GEMS II environment and provide an in-depth analysis and evaluation of the TDOA aspects of the system. During evaluation, signals generated from Spirent GPS signal generators as well as data from actual field-test trials are used to provide extensive performance analysis and comparison, with a view to final system integration.