UK’s BBC Radio-Controlled Electric Meter Sunset

This is another episode in the series of Beyond Global Waves.  Standing tall near Droitwich in Worcestershire, England, the Droitwich Transmitting Station is a significant broadcasting facility established in 1934. It was decided in March 1932 to locate the powerful 5XX LW transmitter at Droitwich. This large station, owned and operated by Arqiva, is home to the British Broadcasting Corporation’s (BBC) most powerful longwave transmitter. The site was chosen in December 1932 and bought in March 1933. Originally expected to broadcast at 120kW, the power was increased to 150 kW by November 1933, adhering to the Lucerne Plan. The two 213-metre-high (700 ft) guyed steel lattice radio masts, 700 ft apart, are visible from a long distance, especially at night with their aircraft warning lights. The whole opening of the station took place on Sunday, 7 October 1934.

The Droitwich station broadcasts on long wave (LW) and medium wave (MW) frequencies. While it transmits BBC Radio 5 Live and Talksport on medium wave, and formerly Absolute Radio, a key function has been the transmission of BBC Radio 4 on 198 kilohertz long wave (originally 200 kHz). This longwave signal is not just for radio programming; since the early 1980s, it has carried the Radio Teleswitching System (RTS) data encoded using phase modulation. Energy suppliers use RTS to switch electricity meters, such as those for Economy 7 and Economy 10 tariffs, between different rates at specific times of the day. The signal carries time-of-day information and radio teleswitch control signals. The BBC delivers this signal on behalf of the Energy Networks Association (ENA).

However, the era of the longwave signal from Droitwich is drawing to a close. Reasons include budget cuts announced in 2011 with no reinvestment in long wave transmissions, and a reliance on rare glass valves, with fewer than 10 left globally, making remanufacturing hazardous. While the separate programming for BBC Radio 4 on longwave ended on 15 April 2024, the longwave signal will continue until at least 30 June 2025. This extension is necessary to allow for the cessation of the radio teleswitching service usage. As of January 2025, approximately 600,000 UK customers still use RTS meters. This transition requires these customers to be upgraded to smart meters, though the sources note smart meter rollout and functionality challenges.