CPU, Frame Generator, and Clock Modules
T1/E1 Frame Generator Module with Clock Bypass
202
TSG-3800 User’s Guide
12778474-002-2 Revision F – March 2004
The SSM being inserted into the bit stream is written to a register on the Frame
Generator module by the CPU module. The SSM can be automatically determined
and inserted, or it can be manually set. For a description of the SSM function, refer
to the
FG
command in
Software Commands
, on page 323.
Clock Bypass Function
The Clock Bypass function is controlled by jumpers W2, W3, and W4 (see
Figure
6-11
). If two Frame Generator modules are installed, these jumpers
must
be
configured the same way on both modules.
Jumper W4 specifies the type of signal (DS1 or E1) that may be connected to input
1.1 (PRI) and input 2.1 (SEC), if they are to be used for the Clock Bypass function.
Set this jumper as required. If both inputs are to be used by the Frame Generator
module, be sure they are both DS1 signals or both E1 signals. The module does not
support a mix of input signals.
Jumpers W2 and W3 determine whether the corresponding Bypass port may be
used for Clock Bypass: W2 = port 2.1, and W3 = port 1.1). Their normal position is
ENAB (pin 2 connected to pin 1) to enable Bypass. Use these jumpers to disable
one or both of the ports if the signals connected to the corresponding Input module
ports are not suitable for Bypass, or if you do not wish to use the ports for Bypass. If
both ports are disabled, Clock Bypass is disabled.
Although the Frame Generator module uses an external signal for the Clock Bypass
mode, it is not connected directly to that signal. Instead, it uses the signal connected
to the Input module. The Input module provides termination for this signal, or, if the
Input module is set for 3.3 k
Ω
termination, by external equipment. If the device
providing termination is removed, Clock Bypass may not function properly because
the Frame Generator module provides no termination of its own. Therefore it is
important not to interrupt signal termination while the Frame Generator module is in
the Clock Bypass mode.
Installing the Frame Generator Module
The Frame Generator module must be installed in slot 16 or 17 of the TSG-3800
main shelf. See
Slot Location and Keyed Modules
, on page 61. A Clock module
must be installed in the slot that supplies a reference signal to the Frame Generator,
that is:
the Clock module in slots 6-10 works with the Frame Generator in slot 16
the Clock module in slots 11-15 works with the Frame Generator in slot 17
Caution:
The configurations of W2, W3, and W4 are important. If
they are not set up properly, Bypass mode may not be possible and
the outputs of the Frame Generator will be turned off.
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