A global positioning system (GPS) interference electronics support measure (ESM) payload system for unmanned aerial vehicles (UAVs)

Abstract

Modern battlefields depend on GPS for precision navigation and timing. Unfortunately, GPS signals are very-low level and GPS interference, both intentional and unintentional, can severely degrade GPS performance. Unmanned Aerial Vehicles (UAV), which have proven their value on the battlefield, rely heavily on GPS for navigation and flight integrity. Key to continued mission success for UAVs is enhanced anti-jamming capabilities. A revealing test of anti-jamming performance for a UAV is to maintain GPS synchronization, while accurately locating a GPS jammer. A small, modular ESM payload is needed to supply anti-jamming performance for the UAV and secondarily, to use DF techniques to locate the GPS jammer. This paper investigates a small, low-power, low-cost, modular solution to reducing the vulnerability to jamming of UAVs by leveraging commercial off-the-shelf technology. A miniaturized GPS antenna configuration that both lowers susceptibility to GPS jamming, and also allows accurate determination of the GPS jammer’s location, is presented. This GPS antenna arrangement consists of two GPS antenna arrays, one positioned on the top of the UAV (facing skyward) and one positioned on the underside of the UAV (facing the ground). The top antenna array acquires and tracks a minimum of 4 GPS satellites for accurate positioning and timing. The bottom antenna array is used to detect and locate GPS interference, and in coordination with the top array, limits susceptibility to GPS interference. The first action upon detecting GPS interference is to alter the reception pattern of the top GPS antenna array to reduce the amount of interference processed by the GPS receiver. Simultaneously, sampled data from both antenna arrays are used to monitor the effect of the interference and calculate the position of the jammer.