External Connections; Input Reference Signals - Symmetricom TSG-3800 Series User Manual

These common features are shared across the TSG-3800 series, and are described
in the following paragraphs. For additional detail on the modules, refer to Chapters 5
through 7 in this guide.

External Connections

External connections to the main shelf, with the exception of an EIA-232 port
located on the front panel of the CPU module, are available on the rear panel of the
main shelf. The external connections include:
Four connectors for input signals
Two (or four) 50-pin output signal connectors, one for each redundant pair
Power terminal block connector, a primary and a secondary power input
Alarms (Major and Minor) terminal blocks, three sets of Form C alarm
connections per block for Local, Remote and Audio alarms
EIA-232 port for remote monitoring and control
Expansion shelf connector
RJ45 for Ethernet 10Base-T connector, or 15-pin "D" connector

Input Reference Signals

The TSG-3800 series has four input slots and supports up to 12 external input
signals of matching or mixed types: framed, composite clock, and so forth. These
signals are connected to the rear panel of the main shelf. Input signal specifications
for each type of Input module are described in
Each input reference signal is assigned a priority level from one to four for use as
the frequency reference signal, with priority level one being the highest. A priority
level of zero may also be assigned to any of the inputs, which sets that input for
monitor use only. When set to zero, the input is never selected as a reference, but
still provides full performance measurement information. In addition to the
user-assigned priority level, the TSG uses the position of the Input module in the
shelf (left to right) as well as the location of the input on the module (top to bottom)
to select among ports with equal user-assigned priorities. The reference selection
algorithm uses the priority level to along with fault conditions to select which input
reference signal is used for frequency control of the clocks.
Switching between reference signals can occur repeatedly without accumulating
phase or frequency error. This switching can be done revertive or non-revertive.
Restoring the primary reference source can return the TSG-3800 to tracking the
primary signal.
12778474-002-2 Revision F – March 2004
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Overview of the TSG-3800 Series
Features Common to All Models
Chapter 5, Input Modules.
TSG-3800 User's Guide 29