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SECTION 1
INTRODUCTION
OVERVIEW
The CELP (Codebook Excited Linear Predictive) Voice Channel Module
is an analog voice channel card for the TMS-3000, TMS Compact, Univ.
MM+ V4 TDM and the MINIMUX TDM. The CELP module provides
voice encoding algorithms that maximize
voice
channel
bandwidth
utilization while offering low bit rate values of 4.8 and 6.4 kHz. A CELP
module in a TMS-3000 also offers a bit rate of 9.6 kHz. OCM CELP is
covered in GDC Publication 036R340-000.
The CELP Voice Channel Module is used in transmission applications to
maximize available bandwidth. Applications include use in digital ser-
vices such as ASDS (FT-1), ADN, satellite and in feeder applications in
which a customer needs to integrate both voice and data. Voice communi-
cation is two-way simultaneous (full duplex).
The CELP Voice Channel Module consists of two cards; a base card and a
FUNCTIONAL
piggyback card. Voice is first processed by an analog-to-digital conver-
DESCRIPTION
sion on the base card yielding a 64 kHz data rate. This data is then con-
verted to a low bit channel rate through software on the piggyback
card.
The bit rate is 4.8, 6.4 or 9.6 kHz. An echo canceller feature is provided
for large inherent delays involved in the digital signal processing of the
voice channel.
2-state in-band E&M signaling is supported. Overhead bandwidth is not
required through the multiplexer network for signaling.
The CELP Voice Channel Module mounts into the TMS-3000 or TMS
Compact channel or expansion shelf.
In the Univ. MM+ V4 TDM or
MINIMUX TDM it mounts into the channel slot.
The CELP Voice Channel Module utilizes a 600 ohm 4-wire interface with
E&M signaling and connects to the voice terminating equipment via a
GDC standard voice channel connection cable.
The CELP Voice Channel Module (-002) supports Group 3 FAX transfers at
the 6.4 kHz voice multiplexer data rate with in-band E&M signalling.
The CELP Voice Channel Module (-003) supports 4.8 kHz voice only with
in-band E&M signalling.
The CELP Voice Channel Module (-004) supports voice and Group 3 FAX
transfers at the 6.4 KHz voice multiplexer data rate with In-band E&M
signaling. When operating in a TMS-3000, 9.6 kHz is also available.
The CELP Voice Channel Module (-005) supports 4.8 kHz voice only with
in-band E&M signalling. When operating in a TMS-3000, 9.6 kHz is also
available.
1-1
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