Three digital broadcasters have been given only another year to produce an electronic programme guide, although they had asked for an indefinite extension.
The Communications Authority ordered the three to comply with their licence requirements by September 21, 2014.
It said it did not consider their request for an indefinite postponement justifiable.
Digital Broadcasting Corporation (DBC), Metro Broadcast Corporation, Phoenix U Radio and RTHK were required by their licences to launch the guide, showing their current and upcoming programmes, by September 21, 2012.
The deadline was earlier extended for a year to the same day this year.
But three of the operators, excluding RTHK, applied to the regulator in December last year for an indefinite extension.
The authority said the applicants argued that the earlier cessation by DBC had "substantially increased the uncertainties they faced", and as a result, "network enhancement works would not be their top priorities until their business prospects improved".
DBC stopped broadcasting last year after a shareholder's row involving allegations of political interference. The shutdown led to activists and hosts of the city's first digital radio broadcaster staging public protests.
The shareholders reached an out-of-court settlement and the broadcaster resumed operations earlier this year after changes in the management.
The operators also said some manufacturers of digital radios had stopped producing devices that could display the electronic guides.
Professor Cheuk Pak-tong, head of the Baptist University's Academy of Film and a media critic, said the future of digital radio was not very good, especially with the availability of online media. "Nowadays, the general public is only satisfied by a combination of audio and video … It is, after all, not that good without video," he said.
Rejecting the applications, the authority noted that the availability of digital radios enabling electronic guides had been globally low, so it decided to extend the deadline for one more year.
None of the three applicants could be reached for comment last night.
RTHK said it was technically ready to launch its guide but would wait for the others and do it all together.