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 their 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 practical 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 consumer reception.

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 operating network, using a transmitter with reduced MER, showed 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 total energy consumption of the existing in-service Doherty transmitters by between 12 and 17%. This approach will be rolled out to 165 present Doherty transmitters during 2024. This technique could be considered for use in future transmitter equipment designs.

Introduction 

Many broadcasters have recently developed carbon reduction and net-zero strategies. Reducing energy consumption will help meet net-zero targets with significant financial and carbon reduction savings. The BBC has recently published its carbon reduction strategy and plans to reduce its energy consumption on UK terrestrial platforms by 28% by 2030 [1]. The BBC terrestrial transmission networks in the UK are owned and operated by its transmission partner Arqiva who together with the BBC are investigating a range of energy saving initiatives. However, measures taken must be proportionate to the benefits whilst maintaining minimal impact on the audience. Improving the efficiency of the terrestrial networks can be achieved by deploying new, more efficient transmitters but it can be preferable to optimise existing, already operational equipment. Improving existing equipment avoids the carbon impact and cost of replacement. Finally, efficiency measures must maintain compliance with regulatory requirements and must not compromise the long term reliability of equipment.

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