Half-rate voice coding system for mobile radio

A novel speech compression method and its hardware implementation which provide significant improvement in spectrum efficiency for land mobile radio systems are described. The method involves the use of the adaptive selection scheme of the DCT coefficients in conjunction with the pitch prediction to achieve excellent speech quality and low complexity at rates of 5.6 kb/s. The computational simplicity of the coding algorithm makes it particularly well suited to real-time implementation of a significant lower cost than LPC based systems producing similar speech quality. It is seen that DSP realization of the coder results in a viable prototype implementation yielding good speech quality