EndRun Tempus LX GPS, User Manual

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T e m p u s L X G P S U s e r M a n u a l 2
C H A P T E R O N E
sions are monitored from ground stations located around the world and carefully measured relative to
GPS time. The results of these measurements for each satellite are then uploaded to that satellite so
that they may be incorporated into the data contained in its transmissions. The receiver can use this
data to relate the time-of-arrival of the received transmissions from that satellite to GPS time.
All of this means that during normal operation, the source of the timing information being transmit-
ted from each of the satellites is directly traceable to UTC. Due to the nature of the GPS spread
spectrum Code Division Multiple Access (CDMA) modulation scheme, this timing information may
be extracted by a well-designed receiver with a precision of a few nanoseconds. The GPS time and
frequency engine in the Tempus LX does just that.
Where to Use It
Since signals from the GPS satellites are available at all locations on the globe, you may deploy the
Tempus LX virtually anywhere. However, you must be able to install an antenna either on the roof-
top or in a window so that satellite transmissions may be received at least several times during the
day. Once synchronized, the Tempus LX can maintain acceptable network synchronization accuracy
for about a day without GPS reception, by flywheeling on its standard temperature compensated
crystal oscillator.
Because the Tempus LX has been designed to operate in conjunction with existing public domain
NTP/SNTP client software that has been created for use with similar time servers, it may be used
in any computer network environment that is using TCP/IP protocols. Although client software is
available for all platforms, for the most precise applications, the Unix-like operating systems are best
supported.
Main Features
Performance, Reliability and Economy
The Tempus LX provides high performance and reliability combined with low power consumption
and cost. Its internal sub-assemblies are fabricated using state-of-the-art components and processes
and are integrated in a solid, high-quality chassis.
Flexibility
It supports a variety of TCP/IP network protocols compatible with a variety of platforms and operat-
ing systems.
Easy Installation
Its standard 1U high, 19” rack-mountable chassis and rooftop or window-mounted antenna make
installation simpler compared to competing products that require rooftop installation of the antenna.
The rack-mount chassis may be mounted in any convenient location. Connect it to your network
via the rear panel mounted, 10/100Base-T RJ-45 connector and plug in the AC power cord. Initial
network configuration is automatic on networks using the Dynamic Host Configuration Protocol
(DHCP). Manual network configuration is via the RS-232 serial I/O port and a simple Linux shell
script.
Free FLASH Upgrades
Firmware and configurable hardware parameters are stored in non-volatile FLASH memory, so the
Tempus LX can be easily upgraded in the field using FTP and TELNET or the local RS-232 serial I/O
port. Secure upgrades are possible via SSH and SCP. We make all firmware upgrades to our prod-
ucts available to our customers free of charge.