Performance Measurements of the CVSD Speech Coding Algorithm
DEFENSE COMMUNICATIONS ENGINEERING CENTER RESTON VA
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A set of experiments was conducted to evaluate the performance of the Continuously Variable Slope Delta CVSD speech coding algorithm. These experiments quantitatively measured the performance sensitivity of CVSD coding with respect to the algorithm parameters. The parameters examined included time constants, compression ratio, and filter bandwidths. The performance of a CVSD coder in terms of speech quality and intelligibility depends on the values of these parameters. Performance also depends to some extent on the type of implementation that is, analog or digital. In addition to measuring the relative sensitivity of the algorithm to the basic parameters, these experiments were also used to determine an appropriate set of parameters for DCS applications. It was found that CVSD performance is most sensitive to compression ratio. Relatively high values of compression ratio result in the best performance. In addition, the results indicate a user preference for a filter bandwidth of 3 kHz compared with a bandwidth of 4 kHz. Based on these results, certain parameters have been selected for CVSD coder operation under conditions of moderate transmission bit error rates.
- Radio Communications