Overview; Global Positioning System; Physical Description - Symmetricom TimeSource 3100 User Manual

Chapter 1 Overview of the TimeSource 3100

Overview

Overview
The TimeSource 3100 is a Primary Reference Source (PRS) that receives and
processes signals from GPS satellites, and outputs Stratum 1 synchronization
signals traceable to UTC. TimeSource 3100 applications include synchronization for
central offices, radio base stations, transmission nodes, and other instances where
a primary reference source can improve the performance of telephony network
facilities.
The TimeSource 3100 creates timing outputs by ensembling signals from several
sources. The sources include GPS signals, an onboard local oscillator, and optional
E1 or analog and remote oscillator signals. Timing outputs created from the
ensemble are composed of the most stable and least noisy parts of each input.
Synchronization outputs are delivered in a framed, all-ones, E1 or 2.048 MHz
analog signal, a 1 pps signal, T1 signals (optional), and time of day (TOD) signals.
The TimeSource 3100 minimizes timing impairments, such as jitter and wander,
that are created by network and transmission systems. The synchronization timing
is traceable to the GPS, which provides the highest level of synchronization for
telephony networks. The TimeSource 3100 with its GPS input is a stand-alone
office PRS. With the optional inputs ensembled, overall system performance is
improved, and holdover is extended if GPS signals become disrupted.

Global Positioning System

The United States Government developed the GPS navigation system. It is a
satellite-based, radio navigation aid designed to provide global, all-weather, precise
navigation and timing capability to users 24 hours a day.
The satellites, circling the earth at approximately 20.197 km, are arranged in 6
orbits with 4 operational satellites in each orbit. Each satellite has an orbital period
of approximately 12 hours. This configuration assures that a minimum of 4
satellites, and as many as 12, are in view anywhere in the world at all times.
The TimeSource 3100 tracks all satellites within its field of view. The performance of
each tracked satellite is observed and compared to the others, and available for use
in the timing solution. A satellite with unacceptable performance data is dropped
from the timing solution.

Physical Description

The TimeSource 3100 consists of a shelf, a plug-in card, an antenna, cables,
hardware, and software. Optional system configurations include eight additional E1
or analog outputs, two E1 synchronous clock insertion unit (ESCIU) ports, four
IRIG-B TOD timing outputs, or eight mixed E1/T1 outputs.
18 TimeSource 3100 User's Guide 097-72020-01 Revision K – December 2005