Study Of HF Frequency Hopping Signal Reconnaissance Technology

Electronic Countermeasure is now becoming a very important part in modern military field, and communication countermeasure is the most important part in electronic countermeasure. While hopping frequency communication is developing very fast in nowadays military communication, communication countermeasures on hopping frequency communications is more and more important.Based on detailed discussion of FH signal detection and parameter estimation, the model of hopping frequency surveillance system is introduced. This technique is derived from time domain analysis, and is competent in a more complicated electromagnetic environment. The main work of this paper are as follows: based on the basic theory of blind source separation (BSS) and its classical algorithm applied to wireless communications, adopts BSS algorithm to separate the original signals received by array antenna and implement signal recognition based on the time-frequency analysis to each of the resulting signals. After the picking up of the FH signal, the presence detection of frequency hopping signal is done. After the detection of FH signal, parameters can be estimated very effectively.The advantage of the FH signal detection based on the BBS algorithm is proved by detailed analysis and simulation results: the original signals is successfully separated from the mixed signals received by array antenna, under the conditions of knowing little knowledge of signal itself. The character of the separated signals is almost the same as the original ones except of the change of the signals'order and magnitude. Using the FH detection algorithm proposed by this thesis, the FH signal can be picked up quickly from the separated signals with only few samples. The error of the FH signal's parameters which obtained by the final step is acceptable so the original characters of the FH signal is acquired.