DAB Transmitters: Energy Efficiency Optimisation

The requirement to develop sustainable broadcast platforms that support global net-zero targets increases year on year. This paper discusses initiatives developed by the BBC and Arqiva to reduce power consumption in the BBC’s terrestrial DAB broadcast network. In some cases, it is possible to improve efficiency without complete replacement of the transmitters.

Improvements in transmitter technology now allow optimisations to be considered that were not practicable previously. Modern transmitter design often takes advantage of Doherty techniques and power supply optimisation. However further reductions may be possible, going beyond previous assumptions, with negligible effect on reception of the broadcast service.

This work evaluates the opportunity for a trade-off between modulation quality and energy consumption. The impact of modulation error ratio (MER) on DAB reception has been investigated through theoretical modelling and validated using laboratory testing with channel simulation. The results from these studies show that the impact on reception of reduced MER can be less than previously assumed. Field-trials in the BBC network, using a transmitter with reduced MER, confirmed a small-to-negligible impact on reception. This points to power savings that can be made across DAB networks.

The combination of MER change and related power supply optimisation is expected to reduce the energy consumption of an existing in-service Doherty transmitter by between 5 and 18%, depending on configuration. This approach is currently being rolled out to 150 Doherty transmitters. The overall saving across the network is expected to be 12 to 13%. This technique should be considered for use in future transmitter equipment designs. This White Paper expands on a paper that was presented at the International Broadcasting Convention held in Amsterdam in September 2024.

This paper is authored by BBC Research & Development's Ranulph Poole, Adrian Wolmarans, with Phil Kesby, Phil Brown from Arqiva.

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