Hopping Signal Reconnaissance Of Digital Receiver Technology

Electronic countermeasure is an oppositional action that both sides of enemies use the signals being in available electromagnetic spectra and weapon to win the war. FH-SS(Frequency Hopping-Spreading System), which is developed as a result of the demand of electronic countermeasure, has become the main corresponding means to fight with enemies in aspect of the electronic disturbing, orientation, location, capture and wiretapping at present. The main body of electronic scout is receiving. Now as a very potential system in electronic countermeasure system, wide-band digital multi-channel receiver provides most of the performance parameters receivers demanded in system of electronic war.This dissertation mainly discusses the technology of digital receiving about scouting frequency hopping signal. The main content and works of the dissertation are present as follows:(1) Existing methods of digital receiving are summarized, and a whole scheme of scouting frequency hopping signal system is designed using the technology of digital multi-channel receiving.(2) A fast frequency estimator based on DFT is suggested and applied on FPGA. The experiment of estimating frequency hopping signal indicates that the estimator has merit of high speed, little resource and good accuracy under required precision of experiment.(3) Experiment shows that the fast frequency estimator based on DFT gets wrong results with some frequencies. The cause is found out through theoretical analysis, then the accuracy is enhanced through improving precision of the above frequencies.(4) Each functional module of frequency estimation and serial communication port are applied on FPGA. Some parameters are discussed.(5) A demo of operation is designed based on MATLAB, including functions of executing DOS commands, data transmitting, indexes computing and dynamic display.Experiment results and statistic data are shown in the end of this dissertation, which indicate that the system of digital multi-channel frequency estimation based on FPGA has merit of high speed, good accuracy and little resource under required precision of experiment and can do well in estimating frequency hopping signal. The conclusion, which gained in the course of in improving frequency estimator in this dissertation, has theoretical value and practicality in digital multi-channel receiving.