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Ofcom plans small-scale DAB tests for 2015

The broadcasting regulator has published a consultation document on digital radio for smaller commercial and community stations, which could extend the UK's digital radio infrastructure

The Radio Academy Festival TechCon is intended to highlight emerging and maturing technologies that could make an impact on the industry. This year’s event, held in Salford, UK, during October, looked at audio over IP, personalised radio and a whole host of apps but a more established format more than held its own.

According to Peter Davies, Ofcom’s director of content policy (pictured), the existing DAB model for radio stations covering whole counties or large towns, with three to four or even more transmitters working to the “broadcast gold standard”, did not make sense for the 150 or so small-scale broadcasters and 250-plus community services in the UK.

Ofcom is now looking at how these smaller operations could go digital and, Davies said, “not be left behind”. The beginnings of this were in an experimental multiplex based on Raspberry Pi designed by Rashid Mustapha, senior associate with the regulator’s Spectrum Policy Group, and tested in Brighton from September 2012 to January 2013. “That really excited us at Ofcom,” Davies commented, “and the government was so interested it gave Ofcom £500,000 to try to develop this as a solution for small-scale stations.”

One result of this investment is an $85 device developed by Mustapha that is capable of taking “traditional audio”, an IP feed or signals from a satellite receiver and then performing audio coding and multiplexing. This would connect to an up-connector, costing around $150, which converts the feed into RF and drives the amplifier. “We think that with this system the total capital costs of producing an end-to-end system would be £5000 to £6000,” Davies stated.

The Brighton test was also intended to show what frequencies would be available for small-scale DAB. Davies acknowledged that there are not enough frequencies in Band 3 to give all smaller stations their own spectrum space, so “multiplexing is going to be required”. While existing spectrum is limited Davies said Ofcom hopes to be able to release up to another seven blocks of Band 3 to be used at low power.

Further technology and viability test will take place in two phases. The first will be technical trials at Ofcom’s radio monitoring station in Baldock, Hertfordshire to see if the proposed system will work on a single frequency network and that the software works on commercial available equipment. There will be a demonstration of this work at Baldock on 6 November.

The second level will involve the industry with what Davies called “stakeholder trials”. This started with the consultation period, which will determine how the tests are carried out. Test services will operate under Wireless Telegraphy Act licences, with the closing date for applications possibly sometime in March 2015. “People will have to be ready to go on air 12 weeks later,” Davies said. The trials will last for nine-months, with final reports published round the end of 2016.