Digital Voice Systems VC-20-ATC-10B, Руководство пользователя

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Section 2 – VC-20 AMBE™ Vocoder Board Overview
VC-20

ATC-10b Vocoder Board User’s Manual
page 3
The Speech Compression Specialists
D
IGITAL
V
OICE
S
YSTEMS,
I
NC.
2 VC-20 AMBE™ Vocoder Board Overview
2.1 Advanced Multi-Band Excitation (AMBE

Vocoder)
The Advanced Multi-Band Excitation (AMBE

Vocoder) technology is based on the
Multi-Band Excitation (MBE) speech model. This speech model provides a unique
speech coding framework which results in a number of advantages over linear prediction
based speech coders such as CELP, RELP, VSELP, MELP, ECELP, MP-MLQ, and
LPC-10, etc. .
(1)
The AMBE

voice coder (vocoder) was first developed in the mid 1990’s by Digital
Voice Systems, Incorporated. The vocoder maintains speech intelligibility and
naturalness at rates as low as 2.4 kbits/sec. The AMBE

Vocoder system is less
complex than either CELP or VSELP, and therefore, it is easily integrated into low-cost,
low-power, communication integrated circuits.
2.2 VC-20

-ATC-10b Vocoder Board Basic Operation
Connections are made to the VC-20™ - ATC-10b using the attached DIN 41612
connector which is described in Sections 4 and 5. The user must supply the VC-20-MTR
with a 5v digital power supply and a +/-5v analog power supply. It is preferable to
decouple the analog supply from the digital supply by using separate power supplies.
The VC-20™ - ATC-10b can be connected to a modem or similar device as shown in
Figure 3. The modem or the VC-20™ - ATC-10b can generate the clock and framing
signals TXCK, FMEN, RXCK and FMDE. The modem reads the data from the encoder
on the data lines TXD3-0. Simultaneously the decoder reads data from the modem on
data lines RXD3-0. The frame signals FMEN and FMDE are used to signify the beginning
of each data frame for the encoder and decoder, respectively. The required timing
relationship between these signals is shown in Figure 5. In order to operate in this mode,
jumpers 5-14 should be disconnected. If the VC-™ - ATC-10b is generating the clocks
and frames, then jumpers 1-4 should be connected, otherwise, they should be
disconnected.