Design And Implementation Of IFF Response Receiver

With the development of information technology in modern warfare,modern electronic information warfare has become an important part of the war.IFF(IFF)system has become an indispensable part of modern electronic warfare.From the beginning of the twentieth century,with the use of long-range weapons on the battlefield,the accidental injury of its own personnel have continued to appear,each country began to notice the importance of IFF.Western countries were the first to study enemy identification,from the beginning of the M1,M2,M3,MC model to the development of today's M4,M5 model.The M5 model is the latest enemy identification system used by NATO.Compared with previous generations of enemy identification system,it has better advantages of better confidentiality,longer distance and higher recognition probability.In this thesis,we study and design the response receiver in the M5 mode for the enemy identification of the west,and simulate and implement the MATLAB platform and the ISE platform respectively.The main contents of this paper are as follows:Firstly,this thesis studies the working principle and related working modes of M5 mode,analyzes the interrogation signal format and response signal format in M5 mode,and studies the generation process of interrogation signal and response signal.The related baseband signal algorithms in M5 mode are studied,including RS algorithm,Walsh spread spectrum,MSK modulation and demodulation algorithm.With the use of RS coding and Walsh spread spectrum,the M5 model has greater fault tolerance and farther recognition distances.Compared with the PSK modulation in the M4 mode of the previous generation,the MSK modulation can occupy a smaller frequency band in the same symbol rate and improve the spectrum utilization rate.Then,the IFF receiver is designed and simulated.According to the zero-crossing detection method,a demodulation method based on CORDIC algorithm is proposed,and the simulation is carried out on the Matlab platform and ISE platform.In the data transmission mode,the coherent demodulation method is often able to get better results.On the matlab platform,several coherent demodulation methods are simulated and compared.Then,on the ISE platform,The simulation method is simulated and verified.Finally,on the basis of a large number of simulations of the response receiver,the circuit is designed.The ADC chip in the circuit uses the AD9265,providing a sampling rate of 80 MHz.The MSK signal with 70 MHz analog signal is sampled to obtain the digital signal.After digital down-conversion,the phase-finding frequency method based on CORDIC algorithm,FPGA-based platform for baseband signal processing,using noncoherent demodulation method to MSK Signal demodulation,Under the condition of signal to noise ratio(SNR)of 15 dB,The bit error rate is close to the theoretical value.