An Australian Perspective on Digital - Radio World

An Australian Perspective on Digital

In August 2009 we started DAB+ broadcasting covering 13 million people. After 12 months, 155,000 receivers have been sold.
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In August 2009 we started DAB+ broadcasting covering 13 million people. After 12 months, 155,000 receivers have been sold. All existing commercial and government broadcasters AM and FM programs are being transmitted.

There are nine broadcasters per transmitter getting 128 kilobits per second each. Most broadcasters are adding additional digital programs. Individual program data rates vary from 32–128 kbps. All broadcasts are free to air.

Currently all transmitters are between 202–208 MHz. (Around ATSC/NTSC Channel 11). Each transmitter has an effective radiated power of 50 kW, which is also the same power being used for all region-wide, Band 3 DVB-T TV transmitters. All DAB+ transmissions are vertically polarized to optimize portable and vehicle reception. Most DTV Band 3 transmitters are horizontally polarized; however vertically polarized DTV is also used. Once analog TV is switched off at the end of 2013, some of the Band 3 frequencies will be released to expand DAB+ broadcasting.

In 2011 there will be an inquiry into which technology will be used for the 10 million people who have no access to digital radio. For regional areas DRM+ is a good candidate probably using 47–68 MHz (European TV Channels 2–4). Another alternative is DRM30 using the empty 26 MHz band.

For sparsely populated areas then DRM30 using 6–24 MHz bands. Here we are talking of an oval coverage area which is 1500 x 2000 km (930 x 1250 miles)

The advantage of DAB+, DRM+ and DRM30 is that the power of the transmitter is not limited by an analog FM or AM transmission in the same channel. This will make for greater data bandwidth and greater reliability compared to IBOC (HD Radio).

In the United States, the analog TV switchoff has completely freed TV Channels 2–6 or 54–88 MHz. This would release 340 DRM+ channels. DRM+ can transmit in 5.1 surround sound, have slideshows for advertising and hyperlinking to the advertisers' websites. This could also be used in Canada once they complete their NTSC switchoff.

For Canada and Alaska, DRM30 would be good for totally covering the remote regions between towns with satellite-fed retransmitters. So those in vehicles will get radio everywhere.

The FCC and Canadian regulators could follow the Australian example: Establish a six-year moratorium on new licenses for digital or analog radio in the coverage area of the digital transmitters. This has allowed our existing commercial broadcasters to get a return on investment on costs of installation, promotion and running extra programs to attract new listeners.

Links of interest:
Digital Radio Is Coming: tinyurl.com/rwdigital1
Digital Radio Plus: www.digitalradioplus.com.au
DAB+: tinyurl.com/rwdigital2
DBCDE inquiry: tinyurl.com/rwdigital3
DRM Broadcasters’ User Guide: tinyurl.com/rwdigital4

Alan Hughes
Technical Author
Perth, Western Australia