Commenting on digital radio

If you are not a regular reader of our comments section  you may have missed a learned and well informed debate has been raging (well perhaps ‘raging’ is an overstatement) about DAB+ in response to a recent article on ten years since Australia’s digital radio launch.
It has built up a good cross section of opinions about the success of DAB+ in Australia and about the audio quality of transmission.
Here’s your summary of the debate so far:
Anthony the Koala, a regular contributor to various topics we report on, started it all by posting a response to this article about ten years of digital radio:

DAB+ is certainly the level playing field. While FM stations had the advantage since the auctioning of parts of the FM spectrum 30 years ago, and indeed successful bidders paying exorbitant fees to occupy a certain VHF frequency, it gives the opportunity for AM stations who could not afford to bid to participate in transmitting CD-quality sound.

The DAB+ system is an improvement on the test transmissions conducted in the early 2000s using MP3 streaming instead of HE-AAC streaming. The latter system permits more stations to be broadcast for a given ‘fidelity’.

However, while the DAB+ has a superior sound, some of the ‘permanent’ auxiliary stations associated with the main FM or AM station are transmitting on 32kbs stereo. I don’t count Macquarie’s NTS which is mainly broadcasting speech in mono. Nevertheless, 32kbs stereo streams have a “metallic sound”. The sound is acceptable at rates of 48kbs in stereo. ABC-FM, RN and Metropolitan ABC (in Sydney 702 (2BL)) broadcast at 70kbs. In Sydney the best signal is 2GB and 2CH at 128kbs stereo.

He also raised the issue of transmission bands (currently the VHF Band in Australia) and alternative transmission systems for regional areas.
Raymond responded that he was worried that DAB+ has not expanded across the whole Australian continent yet:

So 10 years on, regional centres apart from Darwin, Canberra and Hobart, still don’t have digital radio.

That in itself is a worry about the real commitment of the industry to adopt the medium in the way it trumpeted on launch day a whole decade ago.

He also drew attention to New Zealand’s approach to DAB and why NZ won’t be introducing it any time soon. “It’s a revealing read,” says Rayond, linking to this document

Christer then weighed into the debate saying: “After 30 years still few countries are on the DAB trail. The unique national FM switch-off in Norway is a fiasco.”
GerardW proposed that community radio should move off the FM band to make more space:

Free up the FM Band by moving Community Radio completely to DAB+ and establish a proper FM band populated by Commercial Stations.

A few days later StJohn responded to Anthony, taking issue with his belief that the sound is tinny, and raising the DRM question for large coverage areas:

Anthony, Perth has a 32 kbit/s station and it’s sound is not tiny and the centre of the sound stage is normal volume. At this data rate DAB+ makes a mono signal which is steered around. It sounds as if there has been a reversal of the phase of the left vs right signals prior to encoding. You can simulate this by reversing the connections to one speaker.

Don’t convert the country to FM, the coverage areas become smaller than AM. Use DRM which can sound as good over larger coverage areas, but also transmit pictures and multipage indexed text as well.

That led to a few back and forth comments from both Anthony and StJohn, politely differing from each other’s opinions and adding other interesting technical points.
Anthony has just added a further comment today about India’s DRM transmissions and more about the quality of transmission (Read more about radio in India in our sister publication AsiaRadioToday). One of the questions raised in that post is about Indian commercial radio transmitting in DRM, the answer is that only the national broadcaster AIR currently has some transmissions in DRM, there are no commercial stations broadcasting in digital.
We are delighted that our site stimulates informed, polite debate from all viewpoints. We don’t necessarily agree with all the points made, but we are pleased that readers feel that our publication is the place to have a sensible discussion about issues.
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