Low data rate coding for the homomorphic vocoder
Abstract
The techniques of homomorphic deconvolution as applied to the speech production process have been known for some time. However, an actual complete voice coding structure amenable to low data rate transmission has never been demonstrated. It is shown that the canonic deconvolution method can be reformulated in a straightforward way such that the smoothed log spectrum is produced directly without explicit recourse to the complex spectrum. The smoothed log spectrum is seen to be a relatively well-behaved process and can be encoded using DPCM techniques similar to those previously incorporated in channel vocoder systems. Various combinations of frame period and bits per frame have been tested to achieve transmission rates of current popular interest. It has been found that performance competitive with alternative modern vocoding algorithms can be achieved at rates as low as 2400 bits per second.
- Publication:
-
Imaginative Engineering thru Education and Experience
- Pub Date:
- 1977
- Bibcode:
- 1977ieee.conf...23B
- Keywords:
-
- Data Transmission;
- Homomorphisms;
- Signal Encoding;
- Vocoders;
- Canonical Forms;
- Data Links;
- Data Processing;
- Data Smoothing;
- Transmission Efficiency;
- Communications and Radar