Research On Transmitter-Receiver Isolation Technology Of Jammer

As the electronic environment is becoming more and more complex in wartime, interference device with the capability of receiving and transmitting simultaneously have become an indispensable part of the electronic countermeasure system. Transmitter-receiver isolation has been an important factor affecting the performance of the jammer. When the jammer is in the mode of receiving and transmitting simultaneously, jamming through the space coupling into the receiving antenna will reduce the detection sensitivity, resulting in the difficulty of target detection or the decline of signal quality, and even leading to self excitation, which make the entire electronic countermeasure system in a state of paralysis. In order to ensure the correct detection of radar signal and the effective acquisition of enemy target information, it is necessary to study the effective method of transmitter-receiver isolation to improve the working performance of jammer. For the problem of transmitter-receiver isolation in the practical application, this thesis use anti jamming algorithm and corresponding signal processing flow to isolate the coupling interference that is divided into two categories of repression and deception. This thesis works as follows:For the transmitter-receiver isolation problem that puzzle electronic countermeasure system, the key factors influencing the jammer transmitter-receiver isolation are analyzed, the advantages and disadvantages of common isolation technology at present are explored. Further, the technical principle of transmitter-receiver isolation based on anti jamming algorithm is introduced,and the applicability of the technology is discussed.The mathematical model and mechanism of the suppression jamming are analyzed, which provides the theoretical basis for the following research. For the shortage of the traditional amplitude phase cancellation technology, the cancellation isolation technique based on the character of constant amplitude is studied. Using the characteristics of the radar signal is not correlated with the suppression jamming, that technology reconstruct and eliminate the coupling interference, so as to restore the enemy radar signal which is covered by the coupling interference. In order to solve the problem of constant amplitude algorithm that has little effect on time varying amplitude suppression jamming, the algorithm based on instantaneous correlation is further studied, and its effectiveness is demonstrated.For the problem of correlation between deceptive jamming and radar signal, a isolation method based on feature recognition is studied to eliminate the jamming. the mathematical model and mechanism of deception jamming are analyzed, and the variation of the pull-off jamming parameters is used as the basis for recognition; for some jammer which can simulated the character of echo, the feature parameters of micro Doppler and RCS fluctuation are extracted; for the jamming waveform distortion caused by nonlinear device of the jammer itself, the corresponding feature parameters are extracted to distinguish between coupling interference and radar signal. The simulation result shows that the method at a given SNR has good recognition rate.