Equalization Research Of High Speed Data Transmission System On Vhf Based On M-ARY CPM

With the development of wireless communication technology, the use of wireless spectrum resource rates continue to rise, so the available frequency range is less and less. Facing the increasingly crowded and complex electromagnetic environment. The wireless communication system with high utilization rate of frequency spectrum, high transmission rate, low power consumption, and strong anti-interference ability is becoming the research focus.Based on single channel GMSK high speed data transmission system and the same frequency dual GMSK modulation transmission system operated on VHF band, we research the performance improvement of CPM modulation system.CPM is a kind of constant envelope nonlinear modulation, which has high frequency and power utilization. So it has the very good application prospect in wireless communication environment. CPM is a digital modulation using the phase information, so that the phase of the signal is continuous with the time change. Compared to the other linear modulation which has the phase mutation, such as phase shift keying PSK, frequency shift keying FSK, the CPM signal doesn’t generate phase mutation in the code switching time, so it has a narrow main lobe and lower sidelobes in the frequency spectrum. In addition, CPM has the characteristics of constant envelope, so it is not sensitive to the nonlinearity of power amplifier. As a result, the nonlinear power amplifier in the receiver can work in the saturation state.