QAM Modulation And Demodulation Software Implementation Based On The Software Radio

Software Radio is a new technology with high influence and attention in thewireless communication field. It overturns traditionary inherent radio platformthat face all kinds of functions and mainly in hardware, software radio Startsfrom a common and open angle, using the characteristics of portability, easyoperating and updated quickly unify the hardware and software togethereffectively, and no need to change the structure of inherent hardware, only needto change different software module that can realize the functions of softwareradio. In the wireless transmission channel, QAM is a spectrum with highefficiency, robust of modulation method, It makes us can better enjoy the richand colorful radio business.With the rapid development of computer technology, the traditionalcomputer performance and processing power has been greatly improved. Sogeneral computer can be replaced by the hardware platform which use DSP andFPGA as the core, so it is more convenient for all kinds of signal processing. Thispaper uses computer as the platform, makes the radio communication systemmore flexible, open and inexpensive. this paper, based on the knowledge ofsoftware radio,mainly uses the Broadband intermediate frequency structurewhich has been widespread used currently, and process the digital signal inintermediate frequency. This paper, based on the current situation of thedevelopment of the software radio and basic theory, the details of the QAMsignal demodulation process on the basis of variable frequency and therealization of digital filter, and give the software realization method. First the RFsignal frequency mixing to intermediate frequency signal, and at the front end ofA/D, it will intermediate frequency signal digital, then we can get the information after the processing of the operation platform which is composed ofcomputers. Conversely, the information is modulated by this platform, and trun tothe intermediate frequency signal after D/A, then is sent out by change thefrequency to a radio frequency. This paper, based on the current situation of thedevelopment of the software radio and basic theory, the details of the QAMsignal demodulation process on the basis of variable frequency and therealization of digital filter, and give the software realization method.This paper, based on the development and basic theory of the softewareradio, illustrates the process of modulation and demodulation of the QAM signalin detail, and research on digital frequency conversion and the realization of filter,meanwhile, give the method of the realization of the software.