The Research Of Modulation/Demodulation Algorithm And Modulation Recognition Algorithm Based On The Software Defined Radio

Software Defined Radio (SDR) is a kind of new radio communication architecture which was first proposed in 90's in last century. Its basic idea is to realize all kinds of radio communication functions by software programming based on a programmed hardware platform which is all-purpose, standarized and modularized. Then new functions can be easily realized by adding, amending and upgrading the software.In this dissertation, modulation algorithm and demodulation algorithm of radio communication functions are first researched. Because all software programmings are provided for future DSP programmings, hardware realization should be considered in the programming, that is to say, software algorithm for reducing the hardware operation quantity should be looked for. Software realization method of Digital Down/Up Converter(DDC/DUC) with great operation quantity is deeply discussed. The economical DDC/DUC algorithm is deduced by theory analyzation . And different software realization algorithms for AM, USB, LSB, DSB, 2PSK and 2FSK are proposed by considering their different signals characters. To solve the communication problems of various modulation signals, modulation style should be first automatically recognized in receiver, then corresponding demodulation algorithm is automatically transferred. Automatic recognition flow chart for the above six signals is designed based on the decision theoretic approach , and a improved method of putting this approach into the SDR receiver is also put forward. At length, a hardware platform for modulation is designed, which is based on connecting the McBSPO of the TMS320VC5409,TLV2541 and TLV5636 . AM modulation has been carried out and other modulation signals can also be realized by hardware programming on this platform.