Research And Implementation Of Turbo Code In Shortwave Communication

In recent years, with the high-performance shortwave antenna constantly being devised, shortwave communication in the field of telecommunications has a variety of applications.Especially in the military, wrecker, meteorology, ocean transportation, fishing and other industries, turbo codes are widely used. HF communications use ionospheric reflection to sky-wave propagation. There is multipath interference, time-selective fading, Doppler shift and other factors. HF channel transmission reliability is poor. It is generally believed that there is no way to reach the Shannon theoretical limit. The generation of turbo codes gives a great impact of awareness of the people. Conclusion simulation description, Turbo decoding performance can approach the theoretical Shannon limit. Even if the signal to noise ratio is relatively low, Turbo code can still have a good performance. Therefore, try to extend the application of Turbo codes to shortwave communications. Currently, the new on-line digital signal processor (DSP) emerging. Use the new DSP to achieve Turbo decoding algorithm. The main work and innovation of this paper is as follows.Use matlab to simulate the HF channel. Under Gaussian white noise and an increase in single-path Rayleigh fading conditions, analyse the effects of various parameters on the decoding performance.Calculate the maximum posterior probability based on the MAP decoding algorithm and MAX-Log-MAP decoding algorithm carefully. With poor performance of the MAX-Log-MAP algorithm, Use the McLaughlin series expansion to calculate compactly.Achieve MAX-Log-MAP decoding algorithm. Improve the method of calculation by using the unit module. Finally, Complete hardware implementation. Design shortwave communication receiving end system. Write each sub-module driver code. Analysis and optimize shortwave antenna. Use TMS320C6657DSP to communicate between the internal DSP processors. Use the CCS, SYS/BIOS kernel to complete the development.