Friday, November 16, 2012

AM Radio begins the slow fade

I note discussion in the US radio trade press concerned that Porsche has launched a new model including a car radio that no longer has AM (medium-wave) on it. Actually, this is no something new. The web is full of fixes and complaints that AM reception is not what it used to be. Actually, nothing has happened at the AM transmitter sites, except that in some cases stations are operating with reduced power to save on the expensive transmitter running costs.

The problem is that all kinds of devices in the car  are generating low levels of radio frequency interference right next to the antenna trying to pick up a relatively weak signal from a few hundred km away. And whereas these devices were often shielded with metal to prevent the noise getting out, metal is being replaced by plastic which lets the noise through. The results are horrible to listen to, especially with the engine running. The AM radio in many cars also has a rather narrow AM bandwidth filter, which makes the station sound as though the announcers are wearing clothes-pegs on their noses. I used to enjoy listening to BBC Radio 4 on longwave. But that stopped when I replaced the car and discovered the radio in the new hybrid Toyota had no longwave coverage. Mediumwave coverage was not an enjoyable experience. AM is on the way out, that's crystal clear to me. I note in the US quite a few local tourist information stations operating in national parks or low power stations giving traffic info. They operate on 1610 kHz. Wonder how that information is going to be delivered in the future?
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