Transmitter identification and single frequency network characterization for the CASSIDIAN passive radar sensor

The CASSIDIAN passive radar sensor uses FM, DAB and DVB-T broadcast signals, which are processed by independent systems. Each single system delivers detections in the bistatic range-doppler domain to the tracking system, which performs sensor fusion and delivers finally cartesian tracks to the operator. Because FM is an analog waveform, it is necessary to measure the signal quality and to monitor the instantaneous bandwidth. An important aspect for the performance of the system is to select the best available transmitters for FM. For the DAB and DVB single frequency networks the receiver is synchronized to a single station, but targets can be illuminated by several stations simultaneously. Therefore it is essential to identify the reference station, which is not always trivial for interference constellations with similar power from several directions. All broadcast stations of single frequency network (SFN) radiate the same signal, but with certain delays in order to optimize the receive conditions for urban terrains. A prerequisite for the tracking system is to identify these delay times. These network identification and characterization aspects will be discussed in the following.