Non-cooperation Of Ds Signal Pseudocode Estimates Of Ds Detection Receiver Scheme Design

Direct Sequence Spread Spectrum (DSSS) system is an advanced communication system, which extends the bandwidth of the modulated signal while decreasing the Power Spectrum Density. It has many excellent properties such as Multiple Access, Low Probability of Interception, Anti-Jamming and so widely used in military and civilian communication.We need to detect this kind of non-cooperative weak communication signals and estimate its parameters to obtain the PN sequence as the final goal in electronic counter measure(ECM). Presently, the research on PN sequence estimation mostly concentrates on short-code PN sequence and the calculation of these algorithms is too large to design real time estimation system. The algorithm of long-code PN sequence estimation is relatively much less. Operating against the problem above, this thesis do some relative research and analysis on blind estimate of the PN sequence of DSSS signal and real time receiver system design of non-cooperative DSSS signal. The main work of the thesis can be summarized as follows:(1) The fast algorithm on blind estimate of short-code PN sequence is discussed which is based on the singular value decomposition. The performance of the fast algorithm is analyzing and simulating in computer compared with the fast algorithm based on the conception of segmentation. And the duality of PN sequence estimation and information code estimation is elicited from this algorithm.(2) The thesis researches on the algorithm of the blind estimate of PN sequence of long-code DSSS signal, which is based on the data-lost matrix model. Compared with the fast algorithm based on the conception of segmentation, the simulation results demonstrate the good performance of the algorithm.(3) The approach of PN sequence estimation of synchronous and asynchronous multi-user signal is discussed. And the theoretical analysis and simulation results demonstrate performance affection between users.(4) The improved non-cooperative DSSS signal receiver system design is giving in this dissertation using the fast algorithm of PN sequence blind estimation. The new design can adapt low SNR DSSS signal ( SNR≤? 10dB). The simulation results demonstrate the good performance of new receiver.