So what is RF-over-Fibre technology ?

   RF over optical fiber is small in size, flexible, very low loss and a well established technology using intensity modulation to transmit RF signals over a fibre optic link.  The continued fall in the cost of electro-optical conversion over recent years has led to RF over Fibre being increasingly adopted for applications such as linking satellite teleports to control rooms, live outside broadcast TV,  and enhancing coverage of wireless technologies such as GPS, GSM, WiMax, Tetra and P25 for example by linking remote antennas inside buildings, tunnels and mines. 

There are numerous benefits of using optical fibre based solutions such as:- It offers a number of inherent advantages over the use of coaxial cables or free-space transmission, including:

1. Extensive bandwidth
2. A loss of less than 0.5dB signal loss per km makes the link effectively transparent (see graph below comparing RF over fibre to coax over frequency).
3. Immunity to EMI and RFI due to fibre being a non-conductive medium
4. High reliability
5. Security against signal interception
6. Low maintenance - install and forget technology
7. Future proof connectivity platform
8. Flat frequency response
9. Flexible and light weight for ease of deployment
10. Simple installation

ViaLite is a technology for converting RF signals into optical signals for transmission over optical fiber.  A typical system will consist of three main elements: an optical transmitter, a fiber optic cable and an optical receiver (to convert back to RF).

The system is defined in terms of normal RF parameters, i.e. gain, noise figure, linearity etc., and can be treated as an RF black box by a systems designer.

ViaLite systems use intensity modulation, which is amplitude modulation in the optical domain.  The RF signal applied by the user to the optical transmitter directly modulates the intensity of a light source (e.g. a laser diode).  There is no frequency conversion or analog-to-digital conversion involved.  This technique results in the widest possible frequency response and highest possible dynamic range.  At the optical receiver, the intensity modulated light is converted back into an RF signal using a high frequency photodiode.

Intensity modulation places very demanding requirements on all components in the optical path - particularly the laser diode.  In ViaLite products, these components have been designed for optimum efficiency, noise and linearity performance.   

For a more detailed explanation of the modulation please see our Electro-optical conversion process page. 

Typical Applications

• Antenna remoting
• Satcom ground stations
• GPS timing distribution
• Tetra radio networking
• Communication links from DC-4GHz
• Military communications
• Broadcast VHF/UHF links

Key Benefits

• Maximum signal integrity
• Off-the-shelf delivery
• Future proof
• Safety and EMC advantages
• Rapid deployment
• Low loss RF transmission
• Well established technology
• Transparent to data format
• Non-conductive medium
• Industry-standard installation techniques