The Design And Implementation Of Morse Code Systems Based On Speech Recognition

This thesis researches the auto-detection and recognize of morse signal which is simple and applied in the shortwave communication. Today it still was applied widely, especially in the military area stand the place where it cannot be instead. In long term, the work of decoding the morse's signal were done by manual, a lot of people done the simple and repeatable work day by day. To release the manpower, the paper researchs and achieve the auto-detect and recognize the morse signal so that insteading of the manual work.The frequency range of the speech signal is from 100Hz to 3400Hz. The speech recognize technology do pick up this range's characteristics with digital signal process, then according to the certain deterninal rule determinate the signal's content. The morse's signal is singl frequency and fixed intensity. It's frequency generally appear near 1000Hz which is in the speech frequency's range. Because the signal's expression is simple, it is feasible to process the morse's signal with digital signal process means and to achieve the detection and recognize.Before pick up the speech's characteristics, it is must that take the common use short-time analyzed technology on the speech signal, for example the analog to digital convertion, the end-point detection, the pre-emphasis, taking windows and so on. These are the key technics in the speech analysis.The parameters of Speech signal include tow parts: the time-range and the frequency-range. This thesis use the short-time energy and the short-time crossing zero radio to detect the morse signal's end-point and achieve the good effect.Noise is disavoid in shortwave communication. So selecting fit filter to acquier cleanly signal is very important. Powertram is used to filter the plus noise. In the shortwave signal this technology can filter a majority of the background noise and improve the signal quality.