Net-2000™ Voice Codec Unit
User’s Manual
Page 14
Section 3 – Net-2000™ VCU Control
DVSI Confidential Proprietary
A similar start / stop button is located in the VOIP Mode page. This gives the operator the opportunity
to make vocoder settings changes and activate them without having to switch back to the Status
Page.
Net-2000™ VCU VOIP Mode Settings
Figure 10 Net-2000™ VOIP Settings
Vocoder Type and Rate Selection
Vocoder Type and rate/FEC selection is done from the VOIP Mode window. To set the Net-2000™
VCU vocoder, first select the vocoder mode (AMBE™ / AMBE+™ or AMBE+2™), then select the
Rate / FEC using the Bit Rate drop down menu. The default vocoder is set to AMBE+2™ @ 4000
bps with 0 bps FEC.
AMBE™ / AMBE+ Vocoder
The AMBE™ mode is compatible with DVSI’s AMBE-1000™, AMBE-2000™ and AMBE-2020™
Vocoder Chips. DVSI’s proprietary AMBE® Voice Compression Technology delivers excellent voice
quality even at low data rates. Proven to be a superior alternative to linear predictive model
vocoders, the AMBE
®
Voice Compression Technology has been chosen as the standard for several
major satellite and mobile radio communications systems. The Net-2000™ VCU supports AMBE®
Vocoder bit rates from 2000 to 9600 bps. The rates available are the combination of the speech data
and the Forward Error Correction (FEC).
Independent test results have shows DVSI’s AMBE+™ Vocoder running at 4.8 kbps and 4.0 kbps
outperforms both the ITU G.726A vocoder at 32 kbps and the ITU G.729 vocoder at 8 kbps. This
voice coder builds upon the strengths of DVSI’s previous IMBE™ and AMBE® Technology to provide
toll quality speech with unsurpassed robustness to both acoustic noise and channel errors. The
AMBE+™ Vocoder provides a 2-8 times reduction in bit rate while delivering toll-quality performance
with maximizing bandwidth efficiency