Research On The Synchronization Theory For Spread Spectrum Signal Based On BOC And BOC Derivative Modulation

With the rapid development of Direct Sequence Spread Spectrum (DSSS)communication and the gradually mature of satellite communication technology, thenew characteristics signals is appearing. It is very important to put forward BinaryOffset Carrier modulation in order to adapt to the demands in the new situation, whichhas much steeper autocorrelation function than traditional BPSK modulation. Therefore,it can achieve more effective synchronization performance and better anti-interferenceability. AltBOC signals have obvious characteristics such as same carrier and constantmodulus, and MBOC signals have well autocorrelation characteristics. Nowadays, BOCderivative modulation is becoming the focus of the research. Synchronizationprocessing technology is so critical as the core of the DSSS communication. It will bedirectly used in the process of dispread and demodulation of receiver signals processing,thereby affecting the overall performance of the receiver. BOC and BOC derivativemodulation signals have unique properties of split spectrum and correlation peak, itshould develop more efficient synchronous technology research because of theappearance and application of spread spectrum modulation signals.The synchronous mechanism of the whole frequency band acquisition algorithm,single frequency band acquisition algorithm and optimal selected frequency bandacquisition algorithm are further studied based on the analysis of the generationmechanism and characteristics of BOC and BOC derivative modulation signals.Combining with the pseudo-code and carrier tacking technology, the simulation andanalysis of the algorithms have been completed. However, the existing algorithms havesome insufficient, such as low acquisition accuracy caused by multiple peak errorlocking, low process speed caused by resource waste and high treatment complexitycaused by algorithm design redundancy, ect. In order to improve synchronizationaccuracy, speed and reduce processing complexity, the improved synchronization technology for BOC and its derivative modulation signals has been studied. Thesynchronization and acquisition algorithm for main lobe locking method based on noisereduction has been proposed. The improved algorithm aim at restraining the noiseinterference to the normal communication, and the acquisition precision is greatlyincreased through noise reduction technology.On the basis of theoretical research, according to BOC signals, AltBOC, MBOCand their derivative modulation signals, main lobe locking synchronization andacquisition algorithm based on noise reduction has been simulated. The rationality andeffectiveness of the algorithm is validated. Comparing with the whole frequency bandacquisition algorithm, FFT single sideband acquisition algorithm and main lobesuperposition acquisition algorithm, the accuracy and efficience of main lobe lockingacquisition algorithm based on noise reduction is validated. Furthermore, the assistanthardware design of key module of the synchronization acquisition is completed on theplatform of virtex6-lx240series FPGA.