Researches On Frequency Hopping Sequence Estimation And Tracking Method

With the advantages of strong anti-interference capacity, low probability ofinterception, code division multiple access and great confidentiality, spread-spectrumcommunications, especially frequency-hopping communication attracts extensiveattention. Different from traditional ways, frequency-hopping communication achievesthe goal of realizing the avoidance-type anti-jamming through pseudo-randomfrequency-hopping code control carrier frequency and overcoming the traditionaldefects, then it is widely used in military and civil areas.This thesis focuses on the realization of frequency-hopping signal blind receivingor the track disturbance. Different from the predecessors who conducted the research interms of one process alone, several key processes have been studied, includingparameter estimation of frequency-hopping signal, prediction of frequency-hoppingsequence and the synchronization tracking process and their mutual relations in thepractical application has been analyze. Besides, the influence of parameter estimationwill be considered when predicting the frequency-hopping sequence and thefrequency-hopping track will be researched based on the hopping time and hop period.First of all, estimate parameters of the received frequency-hopping signal，includingfrequency-hopping pattern、hop period and the hopping time; then, frequency sequencevalue of future moments will be predicted according to the estimated frequencies tocontrol output frequency of local frequency synthesizer; lastly, after preliminarysynchronization of hopping time and hop period, synchronization of signal will beachieved with the aid of synchronization track algorithm.In view of the non-stationary characteristic of frequency-hopping signal, timefrequency analysis technology which can show the characters of both time domain andfrequency domain synchronous is adopted in this thesis to estimate the parameters, andafter generalized analysis of performance of all the frequency analysis methods, a jointparameter estimation method based on FFT will be proposed, which not only enhancesthe frequency resolution, at the same time, but also reduces the amount of computation;because of the diversity of frequency hopping sequence, predictive estimation methods of several frequency hopping sequences will be studied respectively and polynomialpredictive models of chaotic FH sequences will be improved, as a result, minimalfrequency sequence points are needed to achieve the prediction effectively, preciselyand accurately; Different from the general capture track process, frequency-hoppingsynchronization process of blind receiving or track type disturbance offrequency-hopping signal may firstly carry on the preliminary synchronization by theestimation of hopping time and hop period, and then complete accurate synchronizationthrough the track algorithm. When the hopping time and hop period are estimatedaccurately enough, the preliminary synchronization had achieved accuratesynchronization of the frequency-hopping signal, which may improve greatly theconvergence rate of frequency-hopping synchronization. The performances of algorithmhave been separately confirmed through the simulation, whose results indicate thesemethods may be applied in the actual combat environment.