When our contacts at Sainsburys informed us that their radio communications into the three lower basement levels of their Holborn Head Office building was causing them a problem, we had to come up with a viable solution that would work first time. We had already supplied and installed a multi-channel UHF Motorola Capacity Plus digital trunked radio system at Holborn and extending this system to cover down into the lower basements presented its own unique issues.

Normally, installation of additional repeaters in the areas of poor coverage and then linking them over an IP network would be the way to overcome this type of coverage issue. However, lack of the required additional UHF spectrum in Central London ruled out this solution. And while splitting the antenna system and running long lengths of feeder cable down the building might have helped coverage into the basements, splitting the available RF power would have had a detrimental effect on the existing radio coverage.

Aware of RF over Fibre technology, we approached Cobham Wireless and with their assistance we proposed a solution that would take a very small amount of RF power from the main radio system, convert these milli-watts of RF power to send over a single run of fibre optic cable, and then convert back to RF at the far end before amplifying and feeding a standard UHF antenna with full power.

Installation of this solution was completed recently and full two-way radio coverage is available on all radio channels, in all basement levels, without the need for additional radio frequencies from Ofcom.