How far can a GPS over fibre system transmit a signal?

A GPS over fibre system can extend your antenna cable up to 10 km without signal loss, providing a reliable alternative to coaxial cable for GPS repeaters, receivers, and timing systems.

What are the benefits of using GPS-over-fibre instead of coaxial cable?

GPS-over-fibre systems are immune to electromagnetic interference, weather, and signal degradation over long distances. They are small, lightweight, easy to install, and support all GNSS/GPS frequencies.

What components are included in a standard GPS-over-fibre link system?

A standard system includes an RF-to-optical transmitter (TX), an optical-to-RF receiver (RX), and power supplies. Optional components include an outdoor antenna, coaxial cables, and pre-terminated fibre optic cable.

GPS-over-fibre link system: extend antenna cable up to 10 km

Extend the reach of an antenna feeder cable up to 10Km and overcome the limitations of a coaxial cable system.

This is a reliable alternative to coaxial cable for applications such as GNSS/GPS repeaters, GNSS receivers, and time synchronization equipment.

Background

To deliver a clean, noise-free input signal to a GPS repeater, or a device such as a Network Time Sychronization unit, an outdoor antenna should ideally be installed at the highest point on the building.

When the length of the coaxial cable between the antenna and the indoor equipment becomes too long, signal strength and quality can degrade significantly due to attenuation and interference.

GPS repeater in a police station ensures communications devices are always visible at the control centre

Coaxial cable limitations

While in-line amplifiers and/or up-rated cables can help reduce signal loss, they can still introduce unwanted noise or distortion. Long coaxial runs also present several practical challenges:

Low-loss cable is thick, heavy, and difficult to install over long distances.
High quality coaxial cable can be expensive.
Electromagnetic interference (EMI) can affect the signal, especially near power lines
These limitations mean that extending GPS antenna cables with coaxial cable alone quickly becomes impractical.

Any, or all, of these factors may mean that it becomes impractical continually to increase the cable length.

GPS over fibre – a reliable and practical alternative

Key Features of the GPS-Over-Fibre System

A point-to-point optical link consists of three main components:

RF-to-optical (TX) module – converts RF signals from the outdoor antenna into light pulses and transmits them down the optical fiber link.

Single mode optical fibre – SC/APC connectors

Optical-to-RF (RX) module – converts the light pulses back into RF signals and passes them to the GPS equipment (repeater | receiver | timing module).

Key features:

All GNSS/GPS frequencies passed (1000 to 1800 MHz)
The transmit unit (TX) provides a DC voltage to the low noise amplifier (LNA) in the GPS antenna
The receive unit (RX) terminates the DC voltage output from the GPS repeater/receiver and presents an impedance that simulates the presence of an antenna
Optical connector type is SC/APC
Power for each unit is provided by an external +12V power adapter

GPS over fibre link system components

Standard link system contains:

1 x HRT-G1-8M-10-H1550; RF to optical TX unit
1 x HRR-G1-8M-60; optical to RF unit
2 x HPS-CB-3 international AC/DC power supply

Optional components available to create a full system:

Outdoor antenna with L-bracket for mounting
Coaxial cable; antenna to optical TX
Coaxial cable; optical RX to end device
Pre-cut and terminated fibre optic cable

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