Research In Short Wave Baseband Serial Modem Algorithm And Implementment In Real Time On PC Platform

Shot wave communication is in use of the ionospheric transmitter to the receiver equipment. It is one kind of HF wireless communication with3KHz bandwidth. Shot wave communication has the biggest characteristics is that it can transmit for a long way without any relaying device. That’s because the ionospheric has litter fading effect for the shot wav communication. And for that reason, the shot wave communication has rapid development in military communication.At the moment, short wave high speed data transmission system mainly for two:parallel system and serial system. And the serial system is the mainstream technology for it has high speed in data transmission and high ratio utilization of spectrum. The subject of this paper is mainly about researching and doing simulation in send module according to National Military Stand. And design the receiver frame,also including this frame implement in real time on PC platform.According to the topic to the emphasis of the study, this paper will consists of three parts.First, the modulation mode in send module,and details in mode. According to National Military Stand, send module will use the (2,1,8) FEC code, short-interweave,then use the8PSK as the modulation mode. The simulation shows that signal through Sqrt Raised Cosine Filter will has no intersymbol interference.Second, details in algorithm used in receiver module.This paper will have the details of algorithm used in receiver module which designed according to send module, including the Wiener filtering algorithm used in frame synchronization, the steepest descent method used in channel equalization, levinsion used to solve the unknown data and the vitebi algorithm.Third, implement in PC platform. The PC use the sound card which has AES3data format as signal receiver. The system will use software developed in MFC platform to solve the unknown data. As the sofeware need to do a lot of calculation, I decide to use the multithreaded programming technology.This technology will make the software solving the unknown data correctly.