Gps Input Module; Functional Overview - Symmetricom SSU-2000 User Manual

Input Module Reference Data

GPS Input Module

Table 7-8. DS1 Input Module Configuration (Continued)
Configuration Setting
MTIE T10000 Limit 2
MTIE Limit 1 Alarm Mode
MTIE Limit 2 Alarm Mode
Alarm Initial Severity
Alarm Initial Delay
Alarm Elevation Time
Port Status
Port Name
GPS Input Module
This section provides user-reference data for the GPS Input module (part number
23413019-000-0) that is used in the SSU-2000 main chassis to provide a timing
reference signal to phase and frequency lock the internal clocks and to produce
phase locked output signals.

Functional Overview

The module consists of a Micro-controller and firmware, SRAM for data storage,
FLASH (which contains the firmware), a GPS receiver (radio), 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 1PPS provided
by the radio. These measurements are used to adjust the frequency of the
oscillators on those modules.
In addition, this module supports the Network Time Protocol (NTP), which is a
function provided by the Communications module. Time-of-day from the Radio is
transferred to the Communications module for distribution to clients connected to
the same network. The Communications module's internal 1PPS is synchronized to
the 1PPS from the Radio.
The GPS Input modules monitor and report the status and performance of the
module and the received radio signals. Each module type communicates with the
Communications module to receive user configuration commands and to report
status and performance back to the Clock modules for frequency control.
162 SSU-2000 User's Guide
Factory Default
1110/2840/1110 0 to 100000
Minor Ignore, Report, Minor, Major, or Critical
Major Ignore, Report, Minor, Major, or Critical
Minor (except LOS Ignore, Report, Minor, Major, or Critical
and level 2 MTIE,
which are Major)
0 seconds 0 to 86400 seconds
86400 seconds 0 to 500000 seconds
Disabled Enabled/Disabled
Any user selected string from 0 to 20 characters
Range
12713020-002-2 Revision D – April 2004