Technology Research Of Wireless High Speed Data Transmission System Operated On VHF Based On GMSK

We know that, GMSK modulation is most notably used in the Global System for Mobile Communications (GSM). In China, GMSK modulation scheme is used in GSM900MHz system and GSM1800MHz system. And we also know that, Laurent decomposes the binary continuous phase modulation (CPM) with a non-integer modulation index into the superposition of amplitude-modulation pulses (AMP). GMSK modulation index is 0.5, and based on Laurent decompose, we can use a de-rotation scheme to induce channel diversity so that two stationary discrete output signals can be generated from baud-rate samples without using additional antennas. Then we can use Viterbi equalizer to demodulation the received signals.In this paper, we will research the wireless high-speed data transmission system operated on VHF based on GMSK. The distance of communication is more than 10km away. So, first, we must research the long distance wireless channel characteristics of VHF. Then, we will study the performance of Viterbi equalizer used in our wireless communication system. And we also study the impact of frequency offset and phase offset on the received signals. Finally, we will research the fixed-point design of this communication system.