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Older guys like us probably associate FM with superior audio quality because that what was being heavily promoted while we were young guys growing up with radio. The younger generations wouldn't make the same distinction between AM and FM. They listen to audio on crappy smartphone speakers and don't think there's much wrong with it, AM probably doesn't sound that unusual to them either.
But ACMA has a mandate to plan spectrum and transmission parameters that provide adequate technical coverage across a licenced broadcaster's licence area and if AM doesn't work in Perth, which it likely doesn't because the soil is very sandy, well then AM doesn't work in Perth.
The Radio industry has always resisted change, particularly if a new receiver is required. The ABC experimented originally in mono. Then some community broadcasters started stereo transmissions followed by capital city ABC FM (Classic) and JJJ. The vested interests in AM broadcasters resisted FM but with the demise of the Australian AM radio manufacturing businesses and the importing of AM/FM receivers FM became popular forcing the capital city commercial broadcasters to pay millions for each licence in an ACMA auction. At that time, 1992, the ABC was offered FM licences for capital cities which they rejected for a fear of losing listeners. The FM rollout for regional radio all down the East coast and most of Victoria continued.
Predecessors to the ACMA had allocated 85 - 92, 94 - 108 MHz to TV which was eventually moved to UHF channels allowing for the above frequencies to FM. This was completed 8 years ago.
The Australian commercial broadcasters were the first in the world to start full time DAB+ broadcasting at high power in 2009 but now generally don't promote it.
Perth is an ideal site to start DAB+ only broadcasting because 2 million people is a large enough market to drive receiver prices down and the transmitter location in the Darling Scarp is high enough to cover the flat coastal plain, however 4 more very low power repeaters will be required.
If we were do do this we would be following Norway and soon Switzerland Listeners would then become aware of the additional programs on digital radio which are competing with Audio on Demand through the internet.
It is much cheaper for the broadcaster and the listener to listen using DAB+ than the internet.
Why is broadcasting so backward?
We use AM which first went to air in 1910
We use FM which first went to air in 1936 and added stereo in 1968
We pioneered DAB+ going to air in 2008 appropriately in our highest population density areas.
Now there is DRM which can cover areas a little bigger than FM with 18 programs per transmitter to the coverage of a whole continent with 3 voice programs.
Contrast that with the mobile phone industry which switches off their oldest generation of phones every 8 years with 3G to be switched off in 2024. Phones can show pictures and text, so can digital radio.
Radio is much more reliable particularly in emergencies than can the internet fixed including smart speakers and mobile. Telstra knows this by making fixed payphones free!
Dear Mr St. John,
Stereo FM was authorised by the Federal Communications Authority ('FCC') in the US using the GE/Zenith multiplexing system, ref: https://www.bbc.com/historyofthebbc/anniversaries/august/experimental-stereo-broadcasting page 5.
https://worldradiohistory.com/BOOKSHELF-ARH/Biography/Armstrong's-Fight-For-FM-Broadcasting-Erickson-1973.pdf, page 46.
But GE/Zenith method was not the first method of multiplexing more than one signal on an FM Carrier.
In 1934, Armstrong developed a method of sending four signals on an FM carrier and patenting an FM stereo system in 1954, https://worldradiohistory.com/BOOKSHELF-ARH/Biography/Armstrong's-Fight-For-FM-Broadcasting-Erickson-1973.pdf, page 20.
Thank you,
Anthony of researching Belfield
Dear Mr St. John,
Further to my post, the GE/Zenith system of multiplexing signals on a FM carrier was approved by the Federal Communications Commission ('FCC') in the US in 1961.
In the context of FM broadcasting, multiplexing involves: the baseband signal is a mono-compatible L+R signal (up to 15kHz), a 19kHz pilot tone and a 38kHz DSBSC difference signal, L-R.
Other signals impressed on the FM may include subsidiary broadcasting subcarrier signals at 67kHz and 92kHz. Applicatiions involve additional broadcasting channels and studio feedback feeds (for OBs).
In addition, there is the RDS service at the subcarrier frequency of 57kHz. RDS involves transmission of station ID (callsign) and other information such as song title, weather and news.
Thank you,
Anthony of exciting and I forgot to mention this, Belfield