It's finally happened. South Africa this week launched digital terrestrial television, ushering in a new chapter in the country's broadcasting history, but one that has arrived many years later than promised.On Monday, Communications Minister Faith Muthambi announced the commencement of "dual illumination", a period in which both the analogue and digital signals will coexist for a time, finally allowing broadcasters to launch commercial services.MultiChoice was first out of the gate, debuting the 12-channel GOtv "Value" bouquet (and a two-channel "Lite" option) on Wednesday.The SABC did not respond to a request for comment about its plans, while e.tv said in an e-mail that the start of dual illumination "requires that the e.tv channel is available on the DTT network", something it has done, and that more channels will follow "in due course".Although the government has announced the start of dual illumination - a process all countries switching from analogue to digital must go through - it has not yet announced the all-important date for the analogue signal to be switched off.Existing and prospective wireless broadband operators - including the big mobile network operators - are waiting on tenterhooks for that date.When the analogue switch-off happens, it will free up tracts of valuable radio frequency spectrum that will be reassigned for broadband.Telecommunications and Postal Services Minister Siyabonga Cwele has promised to provide a policy directive by March 31 on how this "digital dividend" spectrum, and other important frequencies, will be allocated by communications regulator Icasa.Telecoms operators have grown increasingly impatient at the years-long delays in South Africa's digital migration.These have been blamed on, among other things, a high turnover of government ministers; legal wrangling over encryption between commercial broadcasters, with e.tv still pursuing a case against Muthambi at the Supreme Court of Appeal; fights between black-owned set-top box manufacturers; and a protracted dispute over which broadcasting standard the country should adopt.However, significant progress has been made in the past year, in spite of vehement objections from e.tv and other parties to Muthambi's decision to drop encryption in government-subsidised set-top boxes.The first boxes have started rolling off local manufacturers' production lines as part of the not uncontroversial plan to provide free boxes to five million poor households, at a cost of billions.How long dual illumination will last will depend on how quickly consumers take up digital services.Dave Hagen, technical director for digital terrestrial television at M-Net, estimates there are 14million TV households.Of those, five million will get free set-top boxes from the government.Of the remaining nine million,five million already have access to a digital platform such as DStv or StarSat, or the free-to-air OpenView HD, leaving four million homes, or about 28% of the total, that may need to acquire a digital set-top box through retail channels."That's where the challenge comes in," Hagen said. Even 36 months for dual illumination would be "highly optimistic", he said. But that is not something the mobile operators want to hear, he added.Another big challenge was that a majority of the five million households that qualify for a free set-top box didn't have an SABC TV licence, which costs R265 a year, Hagen said. Yet a licence is a requirement when claiming a free box, a fact that could act as a significant brake on adoption...