Research On Passive Locating Systems Based On Digital TV Signals

It is widely known that radar systems are threatened by extra-low flight, stealth technology and anti-radiation missile. So scientists pay more attention to the passive radar systems for their "silence"-not transmitting electromagnetic wave. Recently, the passive radar systems based on civil TV/FM signals have made great progresses due to their low frequencies, wide radiation, not ambiguity in low elevation and high radiating power. It is an inevitable tendency to develop civil digital TV with the advance of technology and the increase of social needs. Therefore, researching the passive radar systems based on DTV signals has great theoretical and practical significance.First, in this paper the characteristics of digital luminance signal and video digital signal after channel coding and multiplexing have been analyzed in order to determine which signal is better for target locating. Second, the passive system block-diagram is proposed, in which the time difference of arrival (TDOA) is utilized to estimate the target location. And the system includes three receivers to receive the same transmitting DTV signal and each of them has two independent antennas to receive direct signal from TV station and reflected signal from target. Third, GDOP (Geometrical Dilution of Precision) has been simulated on different conditions such as different stations layouts, different target altitudes, or different correlation coefficient of measuring distances. Last, after analyzing signal characteristics and locating performance of analog TV, its detecting characteristics and locating performance are compared with those of HDTV signal.