Radio New Zealand International has announced it will begin DRM digital radio simulcasts on one of its high powered international transmitters from next year.

The announcement was made at a Symposium being held in Wellington NZ this week, exploring the possibilities of introducing DRM digital radio into New Zealand and the South Pacific.

RNZI will use a modified Thales transmitter to send the DRM signal, which is expected to increase the quality of the New Zealand national broadcaster’s signal into the pacific region.

DRM experts, Andy Giefer from Deutsche Weller and Lindsay Cornell from the BBC, demonstrated the capabilities of DRM, using low and high bit streams and various encoding settings to vary ‘robustness’ and audio quality.

One advantage of DRM for Pacific broadcasters is that it can deliver higher quality audio than AM and Short Wave analog signals over long distances, with no increase in power levels and the long term possibility of reduced power levels for many broadcasters.

The symposium has been supported by the ABU (Asia Pacific Broadcasting Union) because the technology has potential benefits for Asia Pacific broadcasters.

DRM signals piggy back onto one side of traditional AM carriers, using the top 4.5 kHz of signal to transmit digital audio alongside the normal AM signals. In the future, if AM signals are eventually turned off, then the signal could take over the whole AM frequency, delivering superior quality audio and value added data.

The Symposium’s tests used AAC coding with a form of digital enhancement called ‘SBR’ under MPEG 4 compression to operate the transmitter in various modes, demonstrating the trade off between quality and robustness of signal under varying transmission conditions.

The second day of the Symposium ended with a radio engineer’s dream dinner invitation – a candlelit dinner in the transmitter building at Titahi Bay amidst the lights and dials of the transmission racks (pictured below).