A multistatic passive coherent location system with receiver location constraints

A multistatic passive coherent location system has been designed during an eight month lasting trial starting in the end of 2015. The demonstration system exploits the regional single-frequency network (SFN) of DVB-T transmissions from two transmit stations in the area of Munich, Germany. It features multiple pre-existing receiving sites of a TDOA-based passive emitter tracking system to localize airplanes at a low altitude within a specified observation zone. The receiving sites at predefined locations put a constraint on the multistatic geometry and on the selection of suitable RF components. During the system design, the impact of quantization, oversampling and intermodulation distortions in the digital receivers as well as the peak-To-Average power ratio of the signal of opportunity have been included in the dynamic range computations. Several trial measurements were conducted and the data was evaluated offline by a correlation based method. In a preliminary stage manual identification of the intersections of several ellipsoids has been conducted. The system's capability has been verified to detect and localize civil airplanes departing from Munich Airport which is located about 30 kilometers northeast from the city center. In the first trials, the system was capable to detect civil aircrafts with a margin of up to 43 dB above the noise floor at a distance of 16 km from the first SFN transmitter and over a traveled range of 26 km. The distance from the same airplane to the second SFN transmitter was 65 km and lead to an approximate margin of 10 dB above the noise floor over 75 km traveled range. In the latter case, the DVB-T transmitter is located in the Bavarian Alps at about 1800m ASL height which eased the detection capability at the mentioned traveled ranges.