1-Port And 3-Port Ds1 Input Modules; Functional Overview - Symmetricom SSU-2000 User Manual

Chapter 7 Input Module Reference Data

1-Port and 3-Port DS1 Input Modules

1-Port and 3-Port DS1 Input Modules
This section describes the 1-Port (part number 23413013-001-0) and 3-Port (part
number 23413013-002-0) DS1 Input modules that may be installed in an
SSU-2000.
The 1-Port and 3-Port DS1 Input 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 input ports accept one (1-Port Input modules), or three (3-Port Input modules)
of the following signals: sine or square wave, with frequency of 1, 1.544, 2.048, 5 or
10 MHz, or framed communication type DS1. If the input signal is a communications
type, the module monitors for Alarm Indication Signaling (AIS), Bipolar Violations
(BPVs), Loss of Signal (LOS) and Out Of Frame (OOF) errors. In addition, the
module extracts Synchronization Status Messages (SSMs) from the incoming data.

Functional Overview

The DS1 Input module (1-port and 3-port versions) consists of a microcontroller and
firmware, SRAM for data storage, FLASH (contains the firmware), input signal ports,
and other support circuitry. The primary function of these modules is to perform
time-interval-measurements on Clock module A and Clock module B, using the
reference input signals. These measurements are used to adjust the frequency of
the oscillators on the two Clock modules.
170 SSU-2000 User's Guide 12713020-002-2 Revision F.01 – January 2007