July 7, 2014—In the UK, the national DAB multiplexes use single-frequency-networks (SFN) and so as you drive from say, London to Bristol, listening to BBC Radio 4, you need do nothing with your radio, since the multiplex transmitters are designed to provide coverage in a contiguous fashion along the way.
However, as James Cridland reports, the local DAB multiplexes don''t operate in the same fashion. If you were to drive the same route, from London to Bristol, listening to Heart on DAB, your radio will need to re-tune along the way. (Heart carries local advertising and some local programming, so it's carried on local DAB multiplexes, not national multiplexes.) Many older DAB radios don''t work correctly with service-following such as it is required.
As part of certification for the new digital ‘tick-mark'' many DAB radio manufacturers are testing radios along a new set of test routes, which will remain in place till the end of this year. These test routes have been set up by Digital Radio UK, Arqiva and Global Radio, and enable the manufacturers to ensure that their products are working as they should, under ‘real world'' conditions.
In case you want to drive one of the routes yourself, here''s what to expect:
• The HHB and Northants multiplex is broadcasting the same material on two different frequencies: on channel 10C to Hertfordshire, Bedfordshire, and Buckinghamshire; and on 10C to Northamptonshire. Your radio should transition between the two without you noticing.
• Between Bristol and London, listening to Heart, your radio should only switch if there is the same audio on the local DAB multiplexes along the way. Switching will only occur after commercial breaks since Heart carries local advertising.
• DAB-to-FM links are being tested as well. While driving through the Dartford Tunnel to the east of London, your radio should switch to FM from DAB if you are listening to Magic 105.4 or BBC London.
• While driving between London and Chippenham, you will hear XFM on London''s local multiplex, then via the Berks and North Hants, then Swindon, then West Wilts. You should notice no difference along the route.