Research On Time-frequency Synchronization For CPFSK With Pilot-aided

As a constant envelope signal, continuous phase modulation (CPM) signal is notsensitive to nonlinear characteristic of highly efficient power amplifiers. Thus, we canuse the low cost class C power amplifier to reduce the power loss in the communicationand RF hardware cost. Therefore, CPM signals have been in the specific application inthe power limited system such as satellite communications.Application of the CPM signal is still limited, because of the complexity of Viterbidemodulation and synchronization difficulties. The signal synchronization is thepremise of demodulation algorithm, and it can be seen as uniformity in the time andfrequency between transmitter and receiver. Traditional CPM signal synchronizationmethod is relatively complicated, when considering time synchronization and frequencysynchronization at the same time.So the CPM time-frequency synchronization methodof low complexity plays an important role in theory and implementation.Continuous phase frequency shift keying (CPFSK) signals was the completeresponse of the CPM signals of fixed modulation index. On the basis of the engineeringapplication, the paper designs a pilot-aided CPFSK synchronization method. Thesynchronization method is low complex, and easy to project implementation, includingthe function of timing synchronization, carrier frequency synchronization and framesynchronization.First of all, the paper generalized the pilot-aided CPFSK synchronization. The newmethod of pilot-aided synchronization not only can be applied to MSK modulation, butalso can be applied to CPFSK of rational number Modulation index, making pilot-aidedsynchronization method be more widely applicable.Secondly, performance of the synchronization algorithm is simulated on the base ofsoftware architecture. Of modulation index h=1CPFSK signal as an example, givesthe frame structure, module function division and synchronization process. UseMATLAB to simulate and analysis the pilot-aided CPFSK synchronization keyalgorithm. Under the condition of meet the technical indicators, obtained the specificparameters of synchronization algorithm. Again, the detailed design of the synchronization module is given. Paper studiedthe key module in FPGA implementation method, program and constraint externalinterfaces of each module. The main module of the process has carried on the detaileddesignfrom the aspects of function, power consumption, resources and timingconstraint.Finally, test and analyze the implementation results. Base on the software radioplatform, through three typical test cases, test the actual performance of pilot-aidedCPFSK synchronization method. The tests detect and statistics a plenty of samples.Probability of remains frequency less than2Hz is less than98.32%. Probability ofcapturing time less than2s is less than98.91%. Detection probability is97.12%.The paper research the key technology of time-frequency synchronization forCPFSK with pilot-aided, put forward a method of using pilot-aided CPFSK in projectimplementation and verification. This method gives later researchers a theoretical basisand implementation reference. Promote CPFSK signal applied in satellite measurementcontrol in our country.