Research On Repeater Jamming Processing Technology Based On Slow Frequency Hopping Signal

Since the launch of the world’s first communication satellite in 1958,satellite communication has penetrated into all aspects of military field and daily life.In order to ensure the effectiveness and reliability of satellite communication,satellite anti-jamming communication has always been a hot issue,in which frequency hopping communication has become a mainstream anti-jamming means.With the continuous development of anti-jamming technology of satellite communication,the jamming mode is also improving.It has developed from traditional ground-based jamming to space-based proximity jamming which is more threatening,the most likely to be implemented is repeater jamming.Therefore,the research on repeater jamming processing technology of proximity satellite communication is conducive to mastering the action mechanism of repeater jamming,promoting the development of anti proximity satellite repeater jamming and improving the reliability of satellite communication.In this paper,the performance of slow frequency hopping communication system is deeply studied from two aspects: proximity satellite repeater jamming threat analysis and proximity satellite repeater jamming suppression technology.The main work and research results of this paper are as follows:1.The bit error performance of slow frequency hopping communication system under repeater jamming is analyzed.The influence of proximity satellite repeater jamming on the transmission quality of slow frequency hopping communication under multi carrier frequency division synchronous frequency hopping system is studied,and the bit error performance of the interfered part is analyzed from two aspects of single carrier frequency hopping and multicarrier frequency division synchronous frequency hopping.Through theoretical analysis,the calculation formulas of bit error rate of BPSK modulation and QPSK modulation slow frequency hopping system under repeater jamming and the calculation formula of average bit error rate in the whole process of slow frequency hopping are derived.The changes of bit error rate of the disturbed part of mixed signal with signal-to-noise ratio,jamming signal ratio,forwarding delay,carrier frequency and other factors are quantitatively given and verified by simulation,the results show that it is consistent with the theoretical value,and the derived bit error rate formula has important guiding significance for engineering design.2.Because the traditional anti-repeater jamming method is complicated,restrictive,and the effect is not obvious,so for approaching satellite repeater jamming,a method of repeater jamming suppression based on signal orthogonality is proposed.From the perspective of instantaneous phase,this method takes advantage of the fact that the retransmission jamming signal lags behind the real communication signal to reach the receiver,and designs a frequency hopping frame structure that includes "auxiliary hopping","service hopping" and "control hopping".Use the correlation code with good auto-correlation characteristics transmitted in the auxiliary hop to estimate the forwarding delay,and on this basis,by optimizing the selection of the frequency hopping frequency,the receiving end is at the best sampling decision point for the communication signal during the sampling decision.In terms of the zero-crossing point which is different from the communication signal by pi/2,even if the two are orthogonal to each other,the purpose of suppressing the repeater jamming signal is achieved.Theoretical derivation and simulation results show that the algorithm can suppress forward jamming at the cost of smaller frequency hopping processing gain without increasing the hardware complexity of the receiver,and is close to the bit error performance when there is no jamming.3.Two jamming suppression methods based on repeater jamming reconstruction are proposed: regenerative reconstruction cancellation method and repeater reconstruction cancellation method.The regenerative reconstruction cancellation method demodulates the intercepted signal which is not affected by the repeater jamming and then performs remodulation,amplitude and time delay adjustments,and uses the reconstructed signal as the estimated signal and mixed signal of the repeater jamming for cancellation processing,and then reuse the remaining signal to reconstruct the repeater jamming.Theoretical derivation and simulation results show that the bit error rate of the interfered part signal after the regenerative reconstruction cancellation process is 1d B-2d B different from the theoretical bit error rate under BPSK modulation,which can effectively reduce the received bit error rate;The repeater reconstruction cancellation method directly adjusts the amplitude and delay of the intercepted signal not affected by repeater jamming as the estimation signal of the repeater jamming,cancels the signal with the mixed signal,and then uses the remaining signal for the retransmission signal reconstruction again without demodulation and re modulation.Theoretical derivation and simulation results show that the bit error rate of the interfered part is over 3d B different from the theoretical bit error rate under BPSK modulation after once reconstruction and cancellation.