短波串行MODEM中8PSK维特比软译码的DSP实现

In most of widely used convolutional decoding algorithms,the log-likelihood ratio is commonly used.It is too complex to achieve on hardware platform,if traditional log-likelihood ration calculation method is adopted.This paper prsents a simplified method to quantize constellation considering ideology of transform between space and time.Real-time calculation of log-likelihood ratio is not needed if log-likelihood ratio got for each qantized field. Likelihood ratio is got by looking up in table. Decoding performance is better by amplitude stabilization .It only occupies time rescource of stabilization ,table searching and index calculation.Considering the characters of grey code,the table could be optimized as 1/4 of normal table.