Interference on the medium waves generated by battery-powered cars has prompted several manufacturers (Audi, BMW, Mini, Tesla, and Volkswagen) toeliminate the AM tuner in their battery-powered models (we’ve already discussed it here). But new radio disturbances are on the horizon on which it would be difficult to act. Raising the alarm is the ITU (International Telecommunication Union): induction charging systems generate harmonic frequencies between 500 and 700 kHzthat cannot be eliminated by shielding because they are picked up by the antenna. In theory, U.S. law prohibits interfering with licensed stations, so if electric cars disrupt broadcasters, it is up to manufacturers to comply. Technically, however, it is not easy, and since the electric market moves huge interest (by 2030 in the U.S., one out of every two new cars should be electric) the game is wide open.
Heavy interference, but there may be a solution
Induction charging is convenient because it avoids the use of a cable. But the high powers involved (10 kW for a car, 100 kW for a public service bus) produce “robust” phantom signals. There is also DWPT, based on the same technology, which is used to extend the range of cars (now limited to a few hundred kilometers). It relies on coils placed under the asphalt that transfer energy directly to vehicles that do not have to stop at designated charging stations. What to do then? According to Xperi, stations could transmit digitally with the HD Radio system (for which the company owns the patent) because signal processing and error correction provide greater immunity to noise. (Written by Fabrizio Carnevalini)
Perhaps the officials who decided on the shutdown could have given a less symbolic date, but the public broadcaster’s website speaks clearly: as of September 11, 2022, medium waves will no longer be usable. In the country that invented radio, the last medium-wave broadcast towers will soon fall, without even waiting for the centennial: the first “circular” broadcast by URI (which became EIAR and finally RAI), dates back to October 1924. The news had been circulating since September 2021, when it was learned that the new service contract, the agreement RAI has with the state to guarantee public service, specified that decommissioning would take place within a year. This is the culmination of two decades of cuts: on May 15, 2004, the medium waves of Radio2 and Radio3 had been shut down and merged into the unified Radio 1 network. Then more cuts continued in 2013and 2014. There were few facilities left. And in September there will be a denouement. Will Guglielmo Marconi turn in his grave?
Between May and June 2021 the British public broadcaster will switch off the medium-wave transmitters of another ten local radio stations, because the installations on this frequency range “no longer offer an advantageous quality-price ratio for British citizens”. The migration to digital had been announced ten years ago (in 2011): the first closures began in 2018, followed in 2020 by further deactivations in Scotland, Wales and England. Today, all BBC local radio is receivable on digital terrestrial TV and local DAB multiplexes, on FM or online (via smartphones, computers or smart speakers). Abandoning amplitude modulation will be: BBC Essex; BBC Radio Cambridgeshire; BBC Radio Devon; BBC Radio Leeds; BBC Radio Sheffield; BBC Hereford & Worcester; BBC Radio Stoke; BBC Radio Lancashire; BBC Radio Ulster and BBC Radio Foyle. Two other stations, however, will reduce their coverage area: Radio Wales and Radio Gloucestershire. Listeners are provided with a website https://www.bbc.co.uk/reception/ with alternative listening options, a help line and a telephone for listening advice.
After the great enthusiasm for digital broadcasting in the DRM standard, the Indian government is rethinking the technology to be chosen for the future. Digitization began in 2010, and since then three shortwave and 35 mediumwave systems have been activated; the latter can serve an area of 300-350 km each and two or three are sufficient to cover one of the 29 federal states. However, there are few listeners because the receivers cost too much for the purchasing power of the average Indian: the price is at least 3000 rupees (equal to 42 US$), a huge amount considering that in the country one person out of four lives on 12 US$ per month (below the poverty line). India has been penalized by the fact that it was among the first countries to choose DRM because the industry, concentrating on DAB+ (a technology not considered usable in the country, given the vastness of the areas to be covered) has not realized economies of scale and the price of receivers has remained high. Yet the DRM technology could also be used for the FM band.
Further details in the interesting article by Sreejiraj Eluvangal appeared on ultra news, which reports the statements of Ruxandra Obreja, president of the DRM Consortium and Prakash Javadekar, Ministry of Information and Broadcasting.