Product Overview
SSU-2000 Family of Modules
44 SSU-2000 User’s Guide 12713020-002-2 Revision D – April 2004
Type 1 Clock Module
The Type I Clock module uses a quartz oscillator which meets or exceeds the
performance requirements for ITU and ETSI Type I Slave clocks.
The Type I Clock module reads measurement data from the Input modules,
provides frequency control of the oscillator through DDS circuitry, and generates
reference signals used by the Input and Output modules. For more information, see
Type 1 Clock Module, on page 132.
Communications Module
The Communications module serves as the user interface to the SSU-2000. The
module command interface supports three EIA-232-C connections and one
Ethernet interface for communication with the SSU-2000 system. This module also
logs the unit events into non-volatile memory for inspection at a later date and
reports alarms as they occur. For more information, see Communications Module,
on page 136.
Input Modules
1-Port and 3-Port DS1/E1 Input Modules
The DS1 and E1 Input modules are available with both 1-Port and 3-Port
configurations. These modules receive signals and perform phase measurement
comparisons with the Clock modules that are installed in the SSU-2000. The Clock
modules use this information to phase and frequency lock to the incoming signal.
The data may also be used for monitoring the frequency of incoming signals.
The DS1 and E1 Input modules accept the following signals: sine or square wave
(with frequency of 1, 1.544, 2.048, 5 or 10 MHz) or framed communications type
DS1 or E1. If the input signal is a communications type, the module monitors the
following errors:
Alarm Indication Signaling (AIS)
Bipolar Violations (BPV)
Cyclic Redundancy Check (CRC)
Loss of Signal (LOS)
Out Of Frame (OOF)
The module also extracts Synchronization Status Messages (SSM) from incoming
data. For more information, see 1-Port and 3-Port E1 Input Modules, on page 144,
and 1-Port and 3-Port DS1 Input Modules, on page 153.
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