AM radio–the first band used for commercial radio, which dates back to WWI–has served us well. But with its limited frequency range, issues with static and problems with things like overhead power lines that fuzz everything out, it’s finally time for a change.
The shortcomings of AM were apparently as long ago as the 1920s when lightning messed up reception. FM was supposed to solve the static problem when it was introduced in the 1930s, but thanks to some industrial intrigue and skulduggery, FM technology was suppressed by the powers-that-be (read: RCA) and didn’t really begin to flower until the 1960s. After the 70s, FM became the place to go for music while AM programming was reduced to talk, news and sports.
But the static and power line interference problems have never been solved. Anyone who’s driven in a city with electric transit (Toronto, Vancouver, etc.) will know what I’m talking about. No wonder each year more AM stations migrate to FM. In Canada, there’s a movement by broadcasters to petition the CRTC to allow AM stations to move to FM (or at least simulcast on FM), something that’s currently illegal under prevailing ownership rules. In Canada, no owner can have more than two AM and two FM stations in the same market. If the AMs in such an operation were to move to FM, that would be four FMs, which is illegal. At the same time, though, this rule is in place to ensure that the big broadcasters don’t buy up existing FM properties from smaller operators creating an uncomfortable concentration ownership. It’s a bit of a catch-22, really.
Brazil has decided to phase out low-power AM stations so that more frequency space can be freed up for medium- and high-powered AMs can move to FM. About 80% of Brazil’s AM operators are on board with this plan.
Interestingly, this means that the FM spectrum will have to be expanded to accommodate all these new stations. Currently, the spectrum assign to FM in Brazil is the same as Canada: 87.9 Mhz to 107.9 Mhz. The plan is is to extend that band down to 79 Mhz for all these new stations.
This could be done in Canada, too. Before the phase-out of over-the-air analogue TV, that part of the spectrum was reserved for TV audio. If you had a channel 6 in your market, you’ll know that you could have tuned in the audio by going down to 87.9 Mhz. But now that that part of the dial is free, it could be repurposed for migrated AMs.
More on the Brazilian story here.