Section 1- VC-20™ - ATC-10b Introduction
VC-20
ATC-10b Vocoder Board User’s Manual
page 1
The Speech Compression Specialists
D
IGITAL
V
OICE
S
YSTEMS,
I
NC.
1
VC-20™ - ATC-10b Introduction
1.1
General Information
The Digital Voice Systems, Inc. (DVSI) VC-20™ - ATC-10b voice codec is a full-
duplex real-time voice processing board. The VC-20™ - ATC-10b contains
proprietary
software which implements the Advanced Multi-Band Excitation™
(AMBE™) voice coding algorithm. DVSI grants a licence to its customers to use this
software according to the terms established in the attached
AMBE™ Software END
USER License Agreement
. Use of the VC-20™ - ATC-10b, or any portion thereof,
signifies acceptance of these licensing terms.
The VC-20™ - ATC-10b operates by digitizing an analog speech signal using an on-
board A-to-D converter. This digitized speech is then processed by the encoder and
converted into a data bit stream. This bit stream is output to a modem or similar device.
Simultaneously, the VC-20™ - ATC-10b receives a data bit stream from a modem or
similar device. This received bit stream is processed by the decoder and converted into a
synthetic speech signal which is then converted into an analog signal using the on-board
D-to-A converter. The encoder and decoder are fully asynchronous.
The 4.8 kbps data stream consists of 3.6 kbps of Speech data and 1.2 kbps of Error
Correction Code data. This version of the VC-20™ - ATC-10b software produces high
quality speech at bit error rates up to 4%.
