| Digital mixer is the core equipment used for radio, stage controlling, and music, programming. It is powerful, diverse, covering almost all kinds of audio processing and control, including EQ, Comptessor-Limiters and signal generating, filtering, frequence dividing and so on. In this paper, almost all of the systems were analysed and designed except mixing and scene simulating. In addition, I made some algorithm choosing, simplifying and optimization for features of DSP, in the design process.Research work can be concluded as follows:(1) The appropriate filtering mode for DSP is selected, and level detection algorithm is simplified(2) This paper analyzes the narrow-band graphic equalizer filters problems, and selects ChebyshevII bandpass filter for both computation and performance to achieve the graphic equalizer.(3) Compressor-Limiters:The compression transition curve is simplified at the threshold. Sound head, strong tone tail phenomenon are analyzed.(4) White noise of uniform distribution is implemented with the mixed congruential method. White noise tending to Gaussian distribution is implemented by summing uniformly distributed random numbers according to the central limit theorem. Pink noise filter is implemented by step approximation method based on genetic algorithm, and then it is used to generate pink noise by filtering white noise. Sweep signal generator is implemented. |
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