Direct Sequence / FH Hybrid Spread Spectrum Signal Detection And Parameter Estimation Method

The hybrid Direct-Sequence/Frequency-Hopped Spread-Spectrum(DS/FH-SS) communication has the advantages of both DSSS and FHSS communications. It is an advanced communication system with many excellent properties such as Multiple Access, Low Probability of Interception, Anti-Jamming and so widely used in modern military communications, satellite communications, mobile communications, command-control communications and intelligence( C 3I ) systems.We need to detect this kind of non-cooperative weak communication signals and estimate its parameters as the final goal in reconnaissance. Signal detection and parameters estimation are quite different from those in cooperative communication systems, in which all the parameters about the signal are unknown and the design of algorithms are more difficult. Traditional techniques on detection and estimation are often incapable and new approaches are the main task of the dissertation.1) Based on hybrid DS/FH-SS technology, the DS/FH-SS communication system's operating principle and performance are researched in this dissertation and the system is modeled and simulated through two methods in order to generate signal source. Then spectrums of the signal are compared.2) Based on traditional techniques on detection and estimation of DS signal, we get some simulation results by deducting and simulating the capability of the DS/FH signal which comes from various detection and estimation methods, meanwhile compared them with the simulation results of DS signal. We have intensive discussed on the performance influence and the reasons for the decline in performance, then present a method based on Frequency-Joint technology to deal with the signal. During converting different frequencies to the same IF frequency and superimposing signals, we get a new signal and it can be used for detection and estimation. It avoids the problem of shorter data-processing by frequency hopping.3) Combined with the analysis before, the Frequency-Jiont process is simulated and the signal is used for detection and parameters estimation in this dissertation. The simulation results show that, the Frequency-Joint technology can effectively solve the problems in detection and estimation of hybrid DS/FH-SS signal and it is a practical method. At last, the problems which appear in Frequency-Joint process are discussed and novel schemes for signal extraction are presented. Besides, own thoughts are introduced for the realization in the future.