Study Of 8PSK Modulation And Demodulation Technology Based On FPGA

Software Radio has been proposed as the new communication architecture in recent years. As it is flexible and re-configurable, and it records with the current thought of the communication development, it has become the focus of the research on the design of communication systems. Thus, it is very significant making a thorough and careful study of modulation and demodulation technology based on software radio, especially in the more rapid development of modern communication systems.First, this paper expatiates on the theory of software radio, analyzing and discussing the interpolation and decimation, the bandpass sampling, the digital up/down conversion,them provide the extremely important theory basis to design and realizes the 8PSK modem.Then, the modulation and demodulation techniques of 8PSK is mainly studied in this paper. the methods and basic principles of 8PSK is introduced, and a systematic scheme is given. The modulation and demodulation of 8PSK are implemented in the DSP and FPGA platform. For synchronization used a rapid synchronization algorithm which based on the energy detection, implementation by the correlation, bit synchronization and frame synchronization can be achievement at the same time. For the Doppler frequency correction of burden communication, designed a frequency detector which based on the Automatic Frequency Control (AFC) Loop, through amendment the frequency control word of Number Control oscillator (NCO) to calibrate the local carrier frequency, The algorithm's structure is simple, the amount of computing is small and frequency offset correction fast, has good practicability. Then, and the correction of initial phase in the text presented a simple method of CORDIC. And some of the main issues of FPGA programming were introduced. In the article designed of the adaptive modulation and demodulation modules, using channel estimation to get the bit error rate, as the error rate and SNR to change modulation methods, in order to achieve the best transmission performance.