RTHK will provide a lifeline for listeners of English and Putonghua radio shows facing a limited choice under the new digital radio system. TV stations are required to have an English-language channel, but there is no such rule for digital radio broadcasters. RTHK said this week that, from November, two of its five digital audio broadcasting (DAB) channels would be in Putonghua and two in English. The other will be a Cantonese channel. Metro Broadcast and Phoenix U Radio, another two operators who have been granted 12-year digital broadcasting licences, hold three channels each. They are expected to start broadcasting by the end of next year. The Digital Broadcasting Corporation - the fourth licensed digital broadcaster - launched two of its seven channels on Monday. Digital Broadcasting's ethnic minority channel and 24-hour music channel will include only a small proportion of English shows. Five per cent of music programmes on the Phoenix channel will be in English. RTHK's four channels will copy content from its AM channels, and the fifth will be supplied by China National Radio's Voice of Hong Kong, based in Beijing. 'We hope to serve better our role as a public service broadcaster as the new digital broadcasting era arrives,' said Tai Keen-man, RTHK's assistant director of broadcasting. 'We offer diversified content and emphasise bringing various audiences to go beyond Hong Kong, stepping into the mainland and the world.' Tai said RTHK would launch a publicity drive in October, staging road shows on the new broadcasting platform. Digital broadcasting will rely on seven outdoor signal transmitters, but receptors will not be available for users inside MTR trains at the moment. 'If we are to improve reception inside trains, we will have to install DAB antennas in every single MTR station. The cost will be huge and we have no plan to do so at this moment,' said Tai. 'But we have secured government funding for installation in the city's 11 tunnels, and four will be able to receive DAB signals by next year.' Tai said DAB radio would need time to become popular. While conventional radios can be bought for under HK$100, digital versions will cost about HK$500. Tai said the emergence of new models would push down costs. 'Some producers incorporated the receptor with tube amplifiers, photo frames, and mobile phones. And Hongkongers are willing to buy gadgets, so I am confident DAB will become popular.' He reminded consumers that digital radios bought overseas may not be compatible with the local system. 'The UK is using DAB technology, while Hong Kong uses the DAB+ standard. They can only hold nine channels but we have 18. So UK-made digital radios will not function in Hong Kong.'