Research And Implementation Of Western System IFF Baseband Singal Processing Algorithms

IFF system can identify the target whether is the enemy or not by the communication between interrogator and transponder, so it plays an important role in modern informational war. Western institutions IFF system begins from the basic model M1/2/3/C,and evolved into today’s encryption mode M4/5.The encryption mode-Mode 5 is a new mode in US active IFF system Mark XIIA.And it has a modern encryption computer, which protects the signal so it can’t easily be deciphered or forged.It can be used in air to air, air-to-sea, ground-to-peer environment, so it has important significance.This paper studies the M5 system baseband signal processing algorithms, and completes the Matlab simulation and FPGA implementation of the algorithms, which can be divided into the following three parts:First, this paper studies the baseband algorithms of Western institutions IFF M5 system, including RS codec, Walsh spread spectrum, MSK modulation,synchronization detection algorithm and MSK-Walsh joint demodulation and despreading algorithm. Then a M5 system simulation platform based on Matlab is built,and the statistic of some indicators are completed, such as the system identification probability. The simulation results show that the collaboration M5 system has a high identification probability in low SNR conditions.Then, the hardware implementation structure design and the FPGA implementation of the collaboration M5 system baseband algorithms are completed.The vivado timing simulation results indicate that the M5 signal generation module and signal receiving and processing module are correct. Then the board-level verification of the baseband signal processing algorithms is completed based on XC7A200 T. It’s resource consumption is less than 10% and the maximum frequency can meet the requirement of the system clock. And the results show that the implementation of the baseband signal processing algorithm is correct.Finally, the study of the non-cooperating parties to intercept the M5 signal is complicated. And a data capture algorithm is proposed, which can realize the interception of the original interrogation or report data encrypted by collaborators. And the Matlab simulation of the algorithm is completed, the results show that thealgorithm has a high success rate of interception, and when the SNR is 4dB, the success rate is up to 100%. Then the FPGA implementation of the algorithm based on XC7A200 T is completed, the results show that the function of the algorithm is correct and the implementation complexity is not high.The various test results show that the M5 digital baseband processing system which is designed in this paper can generate qualified interrogation/reply signal,and it can finish the reception of inquiry/response signal with high precision. Besides, Data interception algorithm presented in this article is able to intercept the bits information of M5 interrogation or report signal under some certain conditions.