The shrill cry of the seagull might not be everyone's idea of easy listening but it is the basis of a broadcasting experiment that could transform the British radio industry by showing how stations can be set up at minimal cost.
Brighton-based radio engineer Rashid Mustapha recorded the gulls as part of his personal mission to show that DAB broadcasting could be done on a shoestring with software he downloaded for free.
His success could enable a raft of community stations to broadcast in DAB before the FM analogue frequency is closed down - and potentially encourage pirate broadcasters to haul down their Jolly Rogers and go legal.
"This challenge had been bugging me for a while," Mustapha told The Independent. "It was difficult for me to accept that small local radio stations could never get a foothold on the digital platform. And there was frustration that the radio industry had not really done any work in the area."
With the use of free open source software and a Raspberry Pi educational computer (cost £30), he was able to broadcast from Sussex Heights, a 102m tower block overlooking the English Channel.
Mustapha, 38, is a spectrum engineer at Ofcom and the broadcasting regulator has published his work on Software Defined Radios (SDR) in an official paper which has been causing excitement among broadcasting industry executives and radio buffs this week. "I think this is great news for community stations," said one commentator to a radio forum on the Digital Spy media website. "If they get this right it could spell the end of pirate radio," said another.
The experiment was "privately-funded", said the Ofcom report. What this means is that Mustapha - who was among the pioneers of internet radio and has worked in the radio sector for 20 years - spent £3,000 of his own money pursuing his thesis that a DAB multiplex (allowing several stations to broadcast, including community and student networks) could be built far cheaper than previously thought. "Because I'm a broadcast engineer it's in my blood to go looking for the answer to a problem rather than sit there bitterly complaining."
His biggest problem, having developed the technology over several months, was that a rare pair of Peregrine Falcons was nesting on the top of Sussex Heights. As ornithologists waited for the eggs to hatch, Mustapha watched the same webcam in preparation for a launch of his own. An aerial was mounted on a 4.4m mast on the roof of the tower block, pointing towards the South Downs.
The seagull broadcasts ran for four months until January, with Mustapha driving around the city to measure the strength of the signal. According to figures included in the Ofcom report, a small-scale DAB service could be provided for as little as £1,400 per annum in "baseline cost", compared to the £10,000 annual costs of a small FM station. "The costs for operating an entire multiplex are comparable to those incurred in operating a small scale FM transmission system," said the Ofcom report. "No difficulties are anticipated in finding usable frequency blocks in most areas with a low opportunity cost although further work is recommended in this area."
Mustapha chose seagull noises because birdsong has long been used as a test signal in developing radio technology. The continuous birdsong loop became so popular that the audience registered in official ratings and listeners complained when it was taken off air. Seagull cries are Mustapha's Sussex version of the dawn chorus and his recording's legacy might well be longer lasting.