Translation with SYSTRAN Links

But where did my preferred radio pass?

Publication date: Wednesday, June 13, 2012
Letter of the CSA n°260 - May 2012

Listeners are astonished that their preferred radio becomes inaccessible or changes frequency with only a few kilometers of on their premises. That asks the question of the zones of diffusion.

“Where did my preferred radio pass? ”, wonder listeners not managing more to collect it whereas they are only with a few kilometers of the place where they usually receive it. For example when they go to work and that, suddenly, their radio disappears from the FM band, becoming inaccessible. Some also wonder about the reasons which oblige them to have to change frequency to continue to listen to the same program. Two problems which are explained by the mode of attribution of the frequencies.

Since the opening of the FM band, the attribution of the frequencies at the radio stations was carried out zone by zone, as calls for candidate launched by the Council. Each zone has a number of frequencies varying according to its geographical characteristics, but also of the frequencies used in the close zones. In the border zones, it should be taken care that no granted frequency can scramble those which are used by the adjoining country. In a mountainous region, the frequencies of less are carried that in plain, the relief obstructing the wave propagation. It is thus not possible to use all the spectrum of the FM band in the whole of the zones.

An optimal management of the FM band

In order to improve its offer by an optimal use of the spectrum, the Council identifies new resources while protecting the already authorized frequencies. Calls for candidate are then open and any operator interested by the zone concerned can stand as a candidate to obtaining the frequency.

Following the public consultation held in October 2004, the Council completed an important work of optimization of the FM band. It made it possible to obtain significant profits of frequencies, about 22%. But the number of FM frequencies remains limited and the Council cannot give satisfaction to all the requests.

Technical difficulties of single frequency

All that implies that certain radios assignees of a frequency miss in a zone bordering where she would however ask only to be diffused. A technical side explains moreover why the radios use frequencies different from one zone to another. It is indeed particularly difficult to use the same one on the whole of the territory, because the resumption of a frequency identical on transmitters installed in the vicinity causes important phenomena of jamming. To retain the principle of a single frequency would result in decreasing the number of transmitters possible to install, and thus the cover of the territory.

Today, some stations with national vocation lay out however, in regions sufficiently distant from/to each other, of an identical frequency. But it is impossible to allot this one everywhere, in particular in the border zones where this frequency can be already in service in adjoining countries. Only the radios of motorway lay out on the unit of the territory of frequency 107.7 MHz, but with synchronized transmitters which, although neighbors from/to each other, do not scramble themselves between them because of their cover limited to a band along the layout of the motorways.