Research On Interference Suppression Of Space And Polarization Domain In DTV Based Passive Radar

The passive radar which makes use of broadcast, communication, television and other civil illuminators can be configured to bistatic/multistatic system for target detection and location. This radar has the merit of resisting the radar’s four major threats, and has received considerable interests. As common civil transmitters, digital TV signals used in passive radar have very important meaning.Due to the presence of digital TV single frequency network, the reference and the echo channels include straight path interference signal with the same frequency of different stations, which makes the reference channel wave signal is not "pure" and the echo channel low SIR, So, this article makes the use of direct wave channel spatial filtering methods to obtain a more "pure" direct wave signal, the echo path uses the polarization domain filtering and frequency domain multichannel cancellation algorithm NLMS to suppress the interference, To improve the performance of the whole radar system in single-frequency network environment. The main contents and innovations of this paper include the following aspects:First, the research background, the characteristics of SFN and its major influence on radar signal processing were introduced.Second, the model of the entire signal processing system was given. Due to the model, we divided the whole system into direct wave channel and echo wave channel. So interference suppression was divided into direct wave channel interference suppression and echo channel interference suppression.Third, on the basis of studying the methods of direct wave channel interference suppression, the interference from other transmitters were cancelled by using MUSIC algorithm and DBF. To increase the performance of coherent signals estimation, an improved MUSIC algorithm was studied. An improved sample matrix inversion algorithm was researched; it had good performance, and easy to apply..Fourth, the polarization domain filtering techniques and polarization receiving system reform was studied and the performance of polarization filter was also researched. Simulation result verified that the polarization filter could improve the signal to interference ratio, also verified the effectiveness of polarization cancellation with experimental data. Then dual-channel NLMS adaptive cancellation algorithm was researched, simulation result using the experimental data showed that this algorithm can improve the cancellation gain about 10 dB than traditional cancellation algorithm.Last, the experimental platform was introduced, it realized the data gathering and uploading to computer via fiber and PCI-e interface based on Xilinx V6LX130 T FPGA. The function of the experimental platform was verified using experimental data.