Day/night switching to improve coverage

The Australian Communications and Media Authority (ACMA) has decided to make permanent ‘day/night switching’ arrangements to improve coverage of Adelaide’s 5DN.

Since 2007, 5DN, which operates on AM frequency 1323 kHz, has conducted day/night transmitter power switching trials in Adelaide from Wingfield in North Adelaide. These trials have seen a significant improvement in the coverage of the 5DN service into the Adelaide licence area.

Day/night switching involves increasing the power of an AM transmitter during the daytime only. This takes advantage of the different ways that AM radio signals travel over distance, depending on whether it is day or night.

Restricting the power increase to daytime-only can improve the planned coverage, but is less likely than a nighttime power increase to result in interference to very distant AM radio services operating on the same frequency.

The extended trial was intended in part to flush out any interference problems with the higher power operation, which can happen intermittently or during certain seasons.

The ACMA is also increasing the transmitter power and changing the radiation pattern of the Adelaide Foothills community radio service 5MBS. This will rectify deficient coverage of its licence area. The change in the radiation pattern of the Adelaide high power open narrowcasting radio service on AM frequency 1519 kHz is to reflect actual operating conditions.