Research On Technique Of Detection Of Continuous Phase Modulation

Continuous phase modulation (CPM) is a kind of constant-envelope digital modulation schemes. CPM consists of a large family of signals that are especially suitable for wireless communication,and the common characteristics of these signals are their constant amplitude and continuous phase.The common expression of the CPM signals and the derivation of its power spectral density(PSD) expression were introduced at first,based on these,the PSD of the CPM signals were simulated with a computer,and the result showed that the spectral properties was influenced by all of the modulation parameters.Then,the viterbi demodulation method was researched,and the performance of the method was simulated.Through the analysis of these simulation,the relationship among demodulation performance and the modulation parameters can be clearly found.Then the model of the serially concatenated CPM was introduced,which has high band efficiency, power efficiency and some turbo-like coding performance. Turbo performance simulation based on the3GPP LTE protocol (3rd Generation Partnership Project Long Term Evolution) was conducted.Then through the MATLAB simulation,the performance of the M-ary symbol interleaved SCCPM based on the states of the convolutional codes,system interleaver length,iterative number.modulation index and the shape of baseband pulse was studied.At last,the viterbi algorithm of convolutional code is implemented in VerilogHDL language using QuartusⅡ software of Altera company,as a fundamental of CPM viterbi decoding’s implementation based on FPGA. Functional simulation and waveform simulation were conducted in the modelsim software and the desired simulation results had been achieved.