© 2018 Time & Frequency Solutions Ltd

Disclaimer & privacy statements


Tel : +44 1376 514114

Precision GPS/GNSS based NTP Network Time Servers

Link to Brandywine Communications Website

FAQ : Frequently Asked Questions

Please find the following page of commonly asked questions.

If you have any questions not shown here, then please feel free to contact our friendly sales staff for help and information.

FAQ : Frequently Asked Questions about GPS timing and network products

How does GPS work?

All GPS satellites have atomic clocks, which provide time data that is broadcast on a high frequency. The user’s receiver picks up information from at least four satellites simultaneously, which then measures the time delay for the signal to reach the receiver. This data is then converted into very precise position and time information.

Can I use my GPS antenna inside?

No. To receive GPS information, the antenna must be located outside. It will not work inside buildings. The best location for your antenna is as high as possible (e.g. on a roof or mast) with the antenna in clear view of the sky and away from any sources of possible high frequency electrical interference.

How long can the antenna cable be?

The exact length depends on 1) which antenna is selected (we supply 26, 35 & 40 dB); 2) which cable specification is selected (4 available) and 3) which GPS engine is used. The maximum available is 264m (approx 860 ft)

How do you fit the EMP/lightning filter?

The EMP/Lightning filter is always inserted in the coaxial cable between the GPS Antenna and GPS Receiver. The gas capsule is fitted in the unprotected area. A connection is required between the mounting point and a suitable earth point. Ensure the contact surface of the mounting point is conductive. Fit the filter and tighten the mounting nut ensuring a minimum torque of 6Nm to optimise the contact resistance between the filter body and the mounting plate.

Do I need a separate power feed for the antenna?

No, the antenna is powered by the receiver module via the feeder cable.

How do I know when I have synchronised to GPS?

All GPS receivers require 4 GPS satellites to compute a position and obtain a time offset in the receiver clock.

Our products indicate synchronisation has been achieved by indication on the front panel, often showing the number of satellites that are being tracked and also the synchronisation status. The menu also allows the examination of which satellites are being tracked as well as the signal to noise ratio.

Please refer to the reference manual of the relevant equipment for a more detailed understanding and operation of your equipment.

What do I do if I am having GPS synchronisation problems?

If after following the checklist below you still have synchronisation problems, please do not hesitate to contact us.
1.   Check antenna is plugged into the receiving equipment.
2.   Check antenna alignment – High Performance Antenna should be mounted vertically with the white bullet dome facing the sky.
3.   Check that there are no high frequency electrical interference sources near to the antenna.
4.   Check antenna integrity, i.e. no water ingress, lightning strikes or perished cable.
5.   Check receiver equipment against known working system or antenna
6.   Allow sufficient time for synchronisation to occur – this could take 30 minutes for a cold-start or 5-10 minutes for a warm start.
7.   Ensure maximum sky coverage available for antenna by mounting on a roof or similar.
8.   Check the maximum length of cable has not been exceeded or that the minimum cable length has been adhered to.
9.   Use the manual to understand what the indicators on the equipment mean. Usually these indicators are useful for locating faults.

What is the difference between MSF and GPS synchronisation sources?

1)  MSF is a low frequency radio signal that transmits GMT & BST, which will automatically change your clocks at the correct time. GPS      transmits UTC, which does not automatically change.
2)  In situations make it impossible for mounting an antenna with enough sky exposure to pick up the GPS signal, MSF can be received      inside buildings whereas GPS cannot, albeit at a reduced synchronisation rate than if an outdoor antenna were available.
3)  Where a disciplined oscillator is specified for use in your timing system, we would recommend GPS synchronisation source, as the       oscillator is disciplined to atomic time.

How far does the MSF signal reach?

MSF is transmitted from Anthorn, Cumbria, England on a frequency of 60kHz with an estimated equivalent monopole radiated power (EMRP) of 15kW. It falls into the very low frequency band (VLF), which means that it has an approximate range of 1000km. The signal is widely used in the British Isles and in nearer parts of Western Europe. Please contact us if you are unsure if you can receive the signal or not.

What is the difference between the VIS and NMS software applications?

VIS stands for Virtual Interface Software and allows you to remotely control a timing system from a networked PC. NMS stands for Network Management System, and is a more sophisticated and flexible system than VIS. It can manage multiple timing systems and gives greater depth of information, e.g trends and fault log reports. The VIS only controls one timing system an only provides the same functionality and information as if you were using a front panel keypad.

What is a network time server?

Network time servers synchronise all the time data on a computer network.

Why do I need a time server when I can get time from the Internet?

Time information is available from the Internet, but this means allowing data to travel through your firewall, increasing the potential risk of hackers or viruses obtaining access into your network. Also, there are few or no guarantees that the information being provided is accurate or reliable.