RAD VC-6/4LB Installation And Operating Manual - page 14
Chapter 1 Introduction
VC-6/LB Installation and Operation Manual
1-6 Functional
Description
1.4 Functional Description
Audio Performance
The VC-6/4LB module provides four (and the VC-6/LB module provides six)
high-quality voice channels. The analog interface is 2-wire.
The voice encoding method employed is toll-quality 64 kbps PCM in compliance
with ITU-T Rec. G.711 and AT&T Pub. 43801.
The user can select the companding law, µ-law or A-law, in accordance with
system requirements. To increase application flexibility, the nominal audio
transmit and receive levels of all the module versions can be adjusted over a wide
range.
Due to the high quality audio reproduction, DTMF signaling is transparently
transferred inband. Therefore, the user can use DTMF signaling as usual, e.g., can
operate the telephone set keypad to access voice mail systems, interactive systems,
etc.
Unidirectional and Bidirectional Broadcast Applications
In addition to the normal (bidirectional) mode of operation, the VC-6/LB modules
support unidirectional and bidirectional broadcasting modes. These modes can be
used in Megaplex-2100 and Megaplex-2104 units equipped with multiple links.
See the
Megaplex-2100 System Installation and Operation Manual
for information
on these applications.
Timeslot Assignment
The modules require one aggregate timeslot per voice channel. This means that
eight VC-6/4LB (five VC-6/LB) modules can support 30 channels over a single E1
link or six VC-6/4LB (four VC-6/LB) modules can support 24 channels over a single
T1 link.
Alternatively, a maximum of up to 11 of either or both types of module can be
installed in a single Megaplex-2100 enclosure, to support between 44 (if all are
VC-6/4LB) and 66 (if all are VC-6/LB) PCM voice channels, which will require
using two E1 or T1 links. The maximum number of modules in a Megaplex-2104
enclosure is four, corresponding to between 16 (all VC-6/4LB) and 24 (all VC-6/LB)
voice channels, requiring a single E1 or T1 link.
The nominal input and output levels are individually adjustable in a wide range,
enabling easy integration in all environments.
The main link bandwidth required by a VC-6/LB module is one main link timeslot
per voice channel. It provides the data in a DS-0 (8-bits) compatible format,
permitting voice channel switching in a DAC-based cross-connect system.
The Megaplex system enables the user to select the main link that will carry the
VC-6/LB channels. For this purpose, the user can specify the main link module (ML
Slot) and port (ML Channel) desired. Full cross-connect capability enables channels
to be routed between any of the installed links.