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GPS repeaters – Frequently Asked Questions

Questions frequently asked about all aspects of a GPS repeater system.

What is EN50155 and what is its relevance to GPS repeaters?

EN 50155 is a European standard that specifies the requirements for electronic equipment used in railway applications.

Published by the European Committee for Electrotechnical Standardization (CENELEC), EN 50155 sets the standards for the design, manufacture, and testing of electronic systems and devices that are intended for use on railway vehicles, including trains, trams, and light rail vehicles.

A full description with an explanation about its relevance to GPS repeaters, is available in this article

What are the differences between GNSS and GPS?

The original, US-owned Global Positioning System (GPS) is just one of a number of Global Navigation Satellite Systems (GNSS) available today.  A full explanation is found here.

What type of cable is used to connect external antenna to the GPS repeater unit?

Signal losses through attenuation are considered when selecting a suitable coaxial cable.

For cable lengths up to 40 meters, we specify RF240.

This is a flexible, low-loss coaxial cable with excellent attenuation characteristics.

For longer distances, up to approx. 70 meters, we specify RF400, which is from the same cable family as the RF240.

This article explains the situation in more detail.

For even longer distances we have the option to insert a GNSS inline amplifier, or use a GPS over Fibre system.

Where Is The Best Place To Install The Outdoor Receiving Antenna?

Ideally the antenna should go at or near roof level to provide an uninterrupted view of the whole sky.
To obtain an accurate positional fix most GPS devices need to receive signals from at least four satellites.

See installation guide for more details.

Do GPS repeaters support SBAS/EGNOS signals?
Yes, the signals from the EGNOS geo-stationary satellites are transmitted on 1575 MHz, which is the same as the GPS L1 signals.  Therefore they pass transparently through the repeater to the indoor space.

The European Geostationary Navigation Overlay Service (EGNOS) is Europe’s regional satellite-based augmentation system (SBAS) that is used to improve the performance of global navigation satellite systems (GNSSs), such as GPS and Galileo. It has been deployed to provide safety of life navigation services to aviation, maritime and land-based users over most of Europe.

There is a very useful one minute video on the ESA website that explains “EGNOS-How does it work?“.

Where Are Your Repeater Products Made?

Repeater products from Roger GPS are designed and built in Finland.

Do I Need A License To Operate A GPS Repeater?
Yes, Ofcom introduced a “light license regime” in July 2012, requiring the purchase of a license to operate a repeater. More details can be seen here with links to the relevant pages on the Ofcom website where you can download a license application form and supporting documentation.
How To Complete Ofcom License Application Form For GPS Repeater

The license application form is available on the Ofcom website.

This step-by-step guide shows how to complete the form with the most accurate information required by Ofcom.

Do Your Products Have CE Approval?
Yes, all our repeaters have CE approval. Additionally they comply with the essential requirements of R&TTE Directive (1999/5/EC)
How Does A GPS System Work?

The GPS satellite signals are picked up by an outdoor antenna, preferably mounted at height and in free space so as to “see” as much of the sky as possible. The received signals travel down a low-loss coaxial cable to a repeater unit inside the building or area that needs the coverage.

The repeater amplifies the signal and re-radiates it inside the building so that GPS devices in that space can lock on to the Global Positioning System as if they are outside.

On What Frequency Does The GPS Repeater Operate?
The repeaters operate on a range of frequencies, depending on the requirement.

Supported signals and frequencies are:

  • GPS L1 1.575 GHz)
  • GPS L2 1.227 GHz
  • GLONASS G1 1.602 GHz
  • Galileo E1 1.575 GHz
  • BeiDou 1.5611 GHz
What Are The Benefits Of Receiving GPS Signals Indoors?

Any GPS devices within the coverage area will be “locked on” to the GPS signal; hence when the device is taken outside the building it doesn’t take any time at all to acquire the signal and obtain a location fix.

This is particularly useful for GPS systems in emergency vehicles that would otherwise incur delays when leaving the covered area.

In a commercial situation, such as a laboratory where GPS-enable equipment is manufactured, tested, repaired or serviced, there is no need to take it outside the building in order to receive a live signal.

Any number of GPS-enabled devices can receive the signal from a repeater unit, so only one outdoor antenna and feeder cable would be needed per system, as opposed to a tangled mess of multiple antennas and cables in a workshop.

Does The Repeater System Require Mains Power?

The repeater unit runs off a 12V DC supply, via an AC/DC adapter similar in size to a laptop phone charger.

This is the only part of the system that requires a mains power supply; however the GPS antenna has an built-in Low Nose Amplifier (LNA) that receives a 5V DC power supply from the repeater via the coaxial feeder cable.

Additionally, the Splitter, Amplifier and Amplifier/Splitter units derive their power supply from the 5V DC emitted by the repeater.

If I Use A Repeater In A Small Space, Can I Adjust Its Output Power?
Yes, each repeater has a gain control to vary the output power according to the requirement. There is a status LED on the repeater that is observed when the gain control is adjusted – the main objective is to avoid feedback between the indoor (re-radiating) antenna and the outdoor (donor) antenna.
I Need GPS Signal In More Than One Room/Area, Is This Possible?

Absolutely – you can use a splitter unit (with an amplifier if needed) to feed the incoming GPS signal to multiple indoor repeater units.

This approach is generally outside the scope of a standard GPS Repeater Kit and would be classed as a custom-designed system – either way just get in touch with FalTech GPS and ask for advice, it won’t cost you to talk to us!

I Need A GPS Time Source Signal A Long Way Underground – How Do I Do That?

Depending on the actual distance from the outdoor antenna to the space where the signal is required, there are a number of options – contact FalTech to ask advice on the best approach for your situation.

You could use low-loss coaxial cable with in-line amplifiers, or if the distance is too great for that we would specify some fibre-optic equipment that can effectively extend the length of the feeder cable up to several kilometres if needed.

Does the GPS repeater system support SBAS signals?

Yes – SBAS stands for satellite-based augmentation system; it is a system that supports wide-area or regional augmentation through the use of additional messages broadcast by satellites.

Typically the information comes from multiple ground stations located at accurately-surveyed points, and is sent to one or more satellites for broadcast to end users. Sometimes referred to as WADGPS (wide-area DGPS).

These signals pass straight through the GPS repeater system to the interior where needed  – contact FalTech for further information.

Can I fly a drone indoors using signal from a GPS repeater?

A repeater provides coverage over quite a large area inside the building.

However, the signal that a drone’s GPS receiver sees will always indicate the fixed location of the outdoor antenna. 

A repeater can provide indoor signal for testing GPS-enabled equipment, but does not provide the means to navigate or locate assets with any degree of accuracy.

More detail here.

Available in kit form or as a bespoke solution

A GPS repeater kit comes with all you need to get indoor GPS signal in your building.

View GPS Repeater Kits

Bespoke Solution ….

For larger areas where one single repeater is not enough we can offer you a custom-designed-system to meet your exact requirement.