DVB-T based Passive Bistatic Radar

The interest for bi- and multistatic radar systems has gone in cycles of approximately 15 years. Currently we are at the peak of such a cycle, which mainly is driven by the interest for Passive Bistatic Radar systems. The most well-known Passive Bistatic Radar systems are Silent Sentry 3 developed by Lockheed Martin, and the Home Alerter 100 developed by Thales. Passive Bistatic Radar systems offer covert air surveillance at a potentially low cost. However, the emerging systems Silent Sentry 3 and Home Alerter 100 are based on FM-radio transmitters of opportunity, where the main drawback is the relatively low bandwidth, resulting in poor range resolution. The long integration time yields fine Doppler resolution. The next generation Passive Bistatic Radar systems will be based on digital transmitters like the Digital Video Broadcast - Terrestrial signals. These systems will not have the range resolution problem, but rather be facing the situation of targets moving through both range and Doppler bins during the system’s signal integration time. Long integration time gives fine Doppler resolution, and problems due to Doppler walk may arise. The relatively high bandwidth of the Digital Video Broadcast - Terrestrial signal gives fine range resolution, and problems due to range walk may arise. These problems have been analyzed in this work, with both simulated and experimental data. Range walk is shown to cause problems for targets having normal velocity and maneuverability, i.e. sub sound velocity aircrafts. Loss of target signal-to-noise ratio when using long integration times were demonstrated by simulations and real life data processing. Doppler walk was shown to be a more rare phenomenon, mostly due to the low maneuverability and speed of the targets of opportunity. However, in the simulated case, Doppler walk of high bistatic accelerated targets is shown. In order to compensate for the range walk, a method to lower the effects of range walk is studied. The method is based on the Doppler information in the Doppler-delay processing. An adaptive processing scheme is proposed, and the advantages and disadvantages are discussed.