Saturday 23 November 2013

DRM+ Offers Solution For Small-scale Digital Radio

DRM+ could be the obvious alternative to the call for delaying the digital switchover from FM coming from smaller commercial stations in the United Kingdom writes Ruxandra Obreja is Digital Radio Mondiale Consortium chairman in an extensive commentary in Radio World International. 

The stations opposing a switchover announcement in December think that their group, about 100 smaller commercial stations, would be severely disadvantaged due to an absence of transmission capacity or unaffordable transition costs. They fear they would be relegated to an analog second tier of broadcasting. And even if they were to go digital, they worry about the high costs of transition with loss of coverage (due to the multiplex nature of DAB) and consequently the loss of audiences and advertising revenue. 

The group dismisses the small-scale DAB solution and argue that a “one-size fits all” approach risks leaving listeners behind and jeopardizes the future of smaller local stations. They ask the government not to hurry, to let listeners and broadcasters set the pace of change, especially as the vacated AM and FM frequencies are mainly suited for broadcasting and there is no plan for their future deployment. 

Ruxandra Obreja suggests that the DRM Consortium offers an immediate solution that could help the local stations digitize, give a new lease of life to AM stations, keep the VHF and AM bands gainfully employed, provide an alternative pathway that would make digitization in the UK and elsewhere a reasonable solution. It is called DRM, the only, open all-band digital global audio broadcasting standard. 

According to a report of the Ofcom small-scale DAB study “DAB is currently an unsuitable replacement technology” for local FM stations. One reason might be the issue of spectrum availability in Band III and its efficient use. A DAB or DAB+ channel is 1.5 MHz wide and in less populated areas a multiplex might contain as little as one program: pure spectrum waste. A DRM+ channel with a similar performance is only 100 kHz wide (half as wide as an FM channel.) The efficiency is even clearer when compared with DAB. 

As a DAB multiplex can carry up to 16 programs, where the full multiplex is not fully utilized it becomes very inefficient. This means that using DRM+ instead would require about 10% of the DAB radiated power. It is widely accepted therefore, that, when replacing FM transmissions on a one-for-one basis, a DRM+ transmission needs much less spectrum and energy than FM in order to provide the same high audio quality. 

As stressed in the paper sent to Ofcom, the most attractive advantage of the DRM system for switchover purposes is that transmissions are maintained on the current model of a single transmitter per service aerial. 

Thus, listeners can be assured that their favorite programming, whether national, regional, local or community based will continue to be available. The switchover can be phased in over a period of time according to individual decisions on a per transmitter and area basis, if necessary making use of the simultaneous dual transmission possibilities offered by DRM. 

Ruxandra Obreja writes that digital radio needs to combine compatible standards according to national needs in order to present broadcasters and listeners with a workable and desirable “digital radio.” Maybe the time has finally come to have a fresher, more holistic, non-partisan and pragmatic assessment of how best to use one or several standards to achieve digitization and change.

The DRM Consortium has its headquarter at BBC in London.

the DRM Consortium report to Ofcom (DRM Response to “SMALL SCALE DAB” Experiment by Rashid Mustapha).