Subject: [NEXTEL-1] DVSI debuts new half-rate vocoder

From: [email-masked]
Date: Sun, 26 Oct 2003 23:42:43 -0500

DVSI debuts new half-rate vocoder
Mobile Radio Technology, Oct 1, 2003

Digital Voice Systems Inc. has introduced a new Half-Rate Vocoder, which represents an advancement in high-performance voice compression for mobile communications.
DVSI's new Half-Rate Vocoder operates at 2'450 bps and includes integrated forward error correction to raise the total channel rate to 3,600 bps.
This represents an improvement in channel capacity over vocoders used in wireless communication systems.
In addition to more capacity, the new Half-Rate Vocoder provides higher voice quality and better robustness to bit errors as illustrated in the graphic above according to DVSI.
The Half-Rate Vocoder is designed for wireless communication systems, including mobile radio and wireless telephony.
For example, DVSI has proposed standardizing this new Half-Rate Vocoder for APCO Project 25 (P25) land mobile radio equipment to double the number of communication channels available for public safety.
DVSI has designed the 3600 bps Half-Rate Vocoder as an extension to the standard 7,200 bps Full-Rate IMBE Vocoder in use throughout P25.
The IMBE Vocoder also was developed by DVSI and was selected for use in P25 about 10 years ago.
Both the new Half-Rate and the older Full-Rate are based on DVSI's Multi-Band Excitation (MBE) technology, which codes speech using a set of MBE model parameters for each frame of speech.
However, the new Half-Rate Vocoder incorporates DVSI's latest technology to obtain excellent performance at half the data rate.
Furthermore, it adds new tone capabilities, soft-decision decoding, and bit stealing for operation at even lower rates (for example, see the 3,300 bps data in the above chart).
The result is that the new Half-Rate Vocoder can both improve system efficiency, by doubling the number of voice channels, and improve overall system performance.
DVSI plans an expanded range of products to support the Half-Rate Vocoder.
Optimized DSP software for the Texas Instruments TMS320C54x is available and versions for other DSP families are planned.
DVSI also is offering its NET-2000-P25 vocoder unit, which serves as Ethernet capable evaluation module that supports both the Half-Rate and Full-Rate Vocoders.
www.dvsinc.com

http://iwce-mrt.com/ar/radio_dvsi_debuts_new/index.htm

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