Ofcom: Revisions to Digital Radio Technical Codes

Ofcom requires the UK’s DAB digital radio broadcasters to comply with certain technical rules which establish a common minimum set of technical standards for the way that DAB signals are transmitted. We are proposing to revise some aspects of these technical rules, to ensure they remain appropriate and proportionate.
The main aim of these rules is to ensure that the signals carrying different groups of radio stations do not conflict or interfere with one another, and to establish common minimum standards for listeners’ experience of the DAB radio.
We are also starting to think about the needs of the forthcoming ‘small scale DAB’ services: small scale DAB is a new ‘tier’ of DAB radio services which Ofcom is expecting to begin licensing on a permanent basis during 2019/2020. The changes we are proposing in this consultation are equally applicable to further roll-out of the local or national multiplexes that may wish to deploy smaller transmitters than previously to fill areas of coverage deficiency.

The main changes that we are proposing are in the following areas:

ACI/blocking procedures – This is a co-ordination process which DAB broadcasters wishing to build new transmitters must go through in order to minimise the risk of causing interference to the reception of existing DAB services in the vicinity of new DAB transmitters. We are proposing to make this process more flexible and timely, while still retaining protections for listeners and broadcasters.

Spectrum masks for DAB – We are proposing to update the spectrum mask in our Code to align with the recognised international specification. A spectrum mask sets limits on the power of signals produced by a practical transmitter system on frequencies above and below the main signal in order to avoid interference to nearby signals. We also set out that it could be possible for DAB services in some circumstances to operate with a less stringent spectrum mask. The alternative mask would potentially allow smaller, lower-cost output filters to be used at transmitter sites, and therefore reduce the capital costs of building new transmitters. We would welcome input from stakeholders on this.

DAB+ audio encoding – We propose to amend the technical rules around the adoption of DAB+ to reduce the potential barriers to stations adopting this more efficient method of audio encoding.

Other detailed revisions and updates – We are also seeking to revise, rationalise, and update several other more detailed technical rules for DAB broadcasters. We intend to add clarification where needed, and to remove potentially burdensome requirements where appropriate. For example, we are proposing to clarify requirements around repetition rates for the signalling which is present in the DAB data stream, and we are proposing to remove certain requirements for the physical availability of transmitter site monitoring equipment.

Source: Ofcom