Study On Counter-Countermeasures Of Blanket Jamming Of Target Indication Radar And Analysis Of Field Data

When subjected to high-power blanket jamming, all aspects of performance of target indication radar will degrade or even completely lose the ability to work. It is necessary to identify and then suppress blanket jamming. The useful signal is extracted from the noise and all kinds of interference to keep the radar working. This thesis proposes several methods to suppress blanket jamming. The main study work is as follows:(1) The model of FM noise interference, comb spectrum interference and smart noise interference after passing a radar receiver are analyzed. FM noise interference and comb spectrum interference are set as pulse model, which is conformed to jammers working mechanism.(2) Study of the three characteristic parameters for identifying noise FM jamming, comb spectrum interference, smart noise and echo/cheating interference.(3) Study of the target position detection method based on multi-pulse accumulation. When transmitting a plurality of signals in radar pulse period, the rational use of multiple cycles of the signal pulse compression accumulation can detect the target position, which lay the foundation for interference suppression.(4) Study of the target position detection method based on phase reconstruction. The radar received signal phase information is used to reconstruct a unit constant modulus signal. The target position can be detected by pulse compression. Both the multi-pulse accumulation and phase reconstruction are foundations of interference suppression.(5) Study of the interference suppression measure based on substitution and filtering method. In the mid-frequency range, the interference can be suppressed by multiplying by itself twice and filtering. The amplitude of the interference and the target echo changed with each other.(6) Study of the interference suppression based on instantaneous cross-correlation and filtering method. Supposing the target echo location has already been found through the methods in(3) and(4), then the echo section can be extract from the signal. The section could be used to make an instantaneous cross-correlation with the radar launch signal. After filtering process, the inverse instantaneous cross-correlation process would be taken.(7) Study of the interference suppression method based on signal characteristics. This method is based on(3) &(4). According to the radar signal relationships between time domain and frequency domain, the extracted echo section can be divided to smaller fragments to be filtered. It is known that the bandwidth of these fragments is far less than the interference bandwidth. So the interference can be suppressed by filtering to filter out most part of the interference.(8) Field target echo data and noise FM jamming data are used to verify the target position detection algorithm and interference suppression algorithm.