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Why do I need a Time Server?
One of the most common problems
associated with modern computers is to know, with some degree of
certainty, what the correct time is. The first problem is the clock
in the computer. Most computers use a simple crystal oscillator
time base that is often imprecise, is very temperature sensitive
and exhibits significant frequency change over time. The second
problem is how to set the clock. Most computers allow the user to
set the clock manually. Setting the clock to an accuracy of one
second is difficult at best. The third problem is what is the reference
used to determine what the correct time is in the first place. When
two or more computers are involved, especially if they are not in
the same physical location, accurate time keeping is difficult indeed.
A network time server supplies the solution to each of the three
problems even when many computers are involved.
How do Time Servers work? A time server is a precision clock
that can be accurately synchronized to an external source of time.
Additionally, hardware and software is included that transmits the
accurate time to the client computers. The Brandywine Communications
Network Time Servers synchronize their internal clocks to the GPS
satellite system. The GPS system ensures time transfer to better
than one-microsecond anywhere in the world. Internal to the time
server is a bundle of software called the network time protocol
(NTP). A small NTP client program is installed into the computers
to be synchronized. Once the IP address, sub-net mask and gateway
addresses are loaded into the client computer(s) the time synchronization
is automatic. The NTP server and clients periodically communicate
in order to transfer the time from the server to the client(s).
The number of clients is essentially unlimited. The accuracy of
the time transfer is about 100 milliseconds in PC applications and
in the order of hundreds of microseconds in workstation applications.
The improved performance in workstations is because high-end workstations
have oscillators that can be disciplined, that is have their clock
frequency adjusted. In large networks traffic on the network can
delay the NTP messages. The NTP software calculates the latency
of the time transfer and provides latency correction.
Why not use the network time services available over the Internet? There are several time servers available on the Internet. Using
them for precise time is not recommended for the following reasons:
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Network conditions may prevent time from being disseminated.
· Distance from the server may create indeterminate network
latency variables.
· The client has no way to trace the time to its ultimate
time source.
· Security firewalls are often required.
How many time servers do I need?
Usually only one time server per LAN is required. One time server can synchronize many client
computers. In order to provide the highest level of security and
reliability it is best to locate the time server on the client side
of the firewall.
Are network time servers easy to install and are they reliable? The time servers from Brandywine Communications are simple to install;
connect the power, connect the antenna, set in the IP address, sub-net
make and gateway address, connect the server to the network, install
the client program in the client computers and the job is done.
All Brandywine Communications network time server products have
proven to be extremely reliable. Years of trouble-free operation
have been demonstrated and are to be expected. Is network security
compromised? No, a time server is a network product like a printer
or file server. The only external connections are to power, the
network and the antenna in GPS models. In GPS installations with
very high security requirements, TEMPEST for example, a fiber optic
antenna installation kit is available.
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Network Time Servers
Network Time Servers provide an economical, easy
to use method for synchronizing the clocks in networked computers.
The internal clock in the time server is synchronized to a traceable,
external time standard using GPS or an IRIG B time code. Using the
NTP protocol the time from the clock in the time server is disseminated
over the network to the clocks in the computers connected to the
network. The time dissemination process is automatic and is transparent
to the user.
Low Cost GPS Synchronized Clocks
The low cost GPS clocks from Brandywine Communications
offer the same high reliability and state-of-the-art performance
as the rest of the Brandywine Communications product line. Designing
in the most often requested features and options results in substantial
cost savings to the customer. The wide range of product choices
makes it likely that the low cost, off the shelf product will do
the job with no costly engineering changes. Applications for low
cost GPS Synchronized Clocks include OEM systems, secure communications
frequency source, range timing, computer centers, and power utility
centers.
GPS 8 : GPS synchronization, Choice of disciplined
oscillator, Time code outputs, Two serial ports, Low phase noise
1, 5, 10 MHz sine waves available, T1, E1, 10.6608MHz available
GPS 4 : GPS synchronization, Low cost, Time code output, Two serial ports, 10 MHz output
Bus Level Computer Clock Synchronization plug-in boards
The board level products are used to precisely time
synchronize one or more computers and/or provide very precise time
to the host or application program. Brandywine Communications offers
the most comprehensive line of plug-in timing boards in the industry,
almost all of the common platforms are supported. These boards offer
the utmost in ease of installation and reliable operation. Drivers
are available for many popular operating systems such as Windows
95/98, Windows NT, VxWorks and DOS. The Brandywine Communications
family of Bus Level plug-in boards provide a reliable, affordable
and easy to use source of precision time to a variety of computer
platforms. The platforms currently supported are VME, cPCI, PMC,
PC-104, ISA and PCI.
Time & Frequency Distribution
FDA-1050 Distribution amplifiers for both time and
frequency are available from Brandywine Communications. The model
FDA-1050 offers wide bandwidth and a space-saving 1U chassis. Fault
reporting indicators are located on the front panel. The FDA-1050
is available with output connectors located on either the front
or rear panels. Applications for the Model FDA-1050 include:
· Time code distribution
· Frequency distribution
· Signal isolation
· Improving system reliability (dual-input with auto-switch
option)
Time and Frequency Systems
The time and frequency systems from Brandywine Communications
offer the utmost in reliability and flexibility. A wide range of
product choices ensures a "custom-like" solution without
expensive, often time-consuming, non-recurring engineering designs.
Both CA code and P(Y) code GPS receivers, single, dual and triple
redundancy plus a wide range of oscillators and output choices are
available. Timing systems from Brandywine Communications are the
products of choice for discriminating customers like Lockheed Martinand
the U.S. Navy. Applications for time and frequency systems include:
· Ship board time and frequency standards
· Secure communications frequency source
· Range timing
· Computer centers
· Power Utility centers
· Application Notes
Model PTS
The PTS is available in either single or dual redundant configurations,
The PTS is based onGPS disciplined Rb oscillator. The outputs include
serial ports, very stable and clean frequency outputs, time codes
and pulse rates. An NTP interface including complete system control
and monitoring using the comprehensive web browser interface is
also included:
· GPS Disciplined Atomic Clock
· Remote Control over ethernet with included browser
· SA-ASM GPS Receiver option
· Network Time Server
· Serial COM port for setup
· 10MHz, 1PPS, IRIG B, ICD-060 serial time code
Model FTSU-100
The FTSU-100 Frequency, Tme & Synthesizer Unit is a companion
to the Model PTS. It is available in both 1U and 2U configurations.
Both types offer low phase noise frequency outputs, 1PPS timing
outputs, IRIG B timing outputs. Multiple outputs of each signal
are available. Fault monitoring for each of the signals is included.
In dual PTS applications the FTSU will act as a transfer switch
should one of the PTS units fail.
· Frequency and time outputs
· Low phase noise frequency output
· 1PPS output
· Hitless fequency switching
TFD8000
The TFD8000 is the flagship of the Brandywine Communications fleet.
It is a highly reliable, extremely flexible time and frequency source.
Reliability and maintainability are features that were "designed
in" to the Brandywine Communications TFD8000, not added-on.
Applications include:
· Telecommunications network synchronization
· Military Secure Communications (C4I)
· Test Range primary time and frequency standard
· Communications Satellite ground station support
· Standards and Calibrations Laboratories
· Frequency Synthesizers
· P(Y) or CA code GPS receivers
· Network Time Protocol (NTP) Time Server
· Status Alarm Monitor
· Quartz, Rubidium, Cesium Oscillator choices
· Time Code Outputs
· Dual/Triple redundancy with Automatic
· Switchover
· Hot Swappable Modules
· 1-5-10 MHz Outputs
· T1/E1 Frequency Outputs
The outputs of the TFD8000 are fully compatible with other Brandywine
Communications products such as Computer Clock Synchronization boards,
Frequency Distribution Amplifiers, and Video Annotators as well
as industry standards such as T1, IRIG and IEEE.
For more information please contact UNITRONIX
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