5th European Conference on Speech Communication and Technology

Rhodes, Greece
September 22-25, 1997

A 3 Channel Digital CVSD Bit-Rate Conversion System Using a General Purpose DSP

Yong-Soo Choi (1), Hong-Goo Kang (2), Sung-Youn Kim (1), Young-Cheol Park (3), Dae-Hee Youn (1)

(1) ASSP Lab., Dept. of Electronic Eng., Yonsei University, Seoul, Korea
(2) AT&T-Labs Research, Murray Hill, NJ, USA
(3) Samsung Biomedical Research Institute, Seoul, Korea

This paper presents a bit-rate conversion system for an efficient communication between two CVSD systems with different bit-rates. To ensure the robustness to external noises, the presented system is implemented in digital domain using a general purpose digital signal processor (DSP). In order to overcome the problems caused by different bit-rate and time-constants, several methods are considered in this study. In addition, a significant simplification of the system complexity is obtained by introducing the IIR filter to the decimation/interpolation process. The use of the IIR filter provides comptational advantages over the conversion system employing FIR filters, because the linear phase is not a critical issue in this application. By modifying the algorithm based on the IIR filter, a 3- channel full-duplex conversion algorithm was successfully implemented on a single DSP. Experimentals results are presented to exihibit the consistent and reliable performance of the bit-rate conversion system.

Full Paper

Bibliographic reference.  Choi, Yong-Soo / Kang, Hong-Goo / Kim, Sung-Youn / Park, Young-Cheol / Youn, Dae-Hee (1997): "A 3 channel digital CVSD bit-rate conversion system using a general purpose DSP", In EUROSPEECH-1997, 665-668.