Design Of Shortwave Channel Simulator Used ITS Model And Realization Method On SDR Platform

With the demand of wireless integrated service transmission growing and the development of adaptive signal processing,channel coding technology,etc.,wideband high frequency(HF)Digital Communication entered a phase of vigorous development.HF communication can achieve long-distance communication without relay,with strong mobility,anti-destructive and fast network reconfiguration,etc.,that still is one of the major methods in the international remote communication.But shortwave equipment test is very difficult,or even the distance between transmitter and receiver is up to thousands of kilometers across.In order to debug the equipment in laboratory,it becomes more and more urgent about the requirement of channel simulator for shortwave staff.Nowadays,the traditional HF channel simulators can not meet the test need of HF equipment because of the narrow bandwidth.This paper aims to achieve a practical and scalable broadband shortwave channel simulator,which is used for fast testing or research and development of wideband HF equipment.Starting from demands of HF channel simulator,the thesis summarizes simulators'development and present situation.Then,shortwave transmission characteristics relying on sky wave is researched,and two typical shortwave channel model--Watterson model and ITS model are analyzed.In order to solve sharp contradiction between the complex characteristics and the implementation capability of simulators about HF channel,a Gaussian curve is used to fit ITS delay power distribution function to get channel model.The calculation method of fading parameter and simulation structure are given,and simulation results show it has the feasibility and easy implementation.Finally,the implementation of HF channel is discussed on the software defined radio(SDR)platform to realize a real-time,broadband,reconfigurable and upgrade model.It contains five parts:general scheme design,the hardware architecture design and configuration,the major algorithm implementation of the simulator on FPGA,the design of user interface and test.Test results basically meet the design index of HF channel simulator,so it can get the main features of the broadband shortwave channel,and proved the feasibility of hardware implementation scheme.