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What You Think

User Opinion Story
Anthony The Koala
20 August 2019 - 7:30am
Dear StJohn,
Thank you for your reply, we are better informed about DRM. Two points, the ubiquity of DRM (or even DAB+), the disposal of e-waste and patent law regarding the HE-AAC codecs.

(1) Ubiquity of AM and FM radios and making DRM as ubiquitous. As a matter of 'common-sense' policy, to switch off the analogue services requires both simulcasting the analogue services and a new DRM (or DAB+) service for a period of time until the market place is saturated with DRM receivers.
(1a) Disposing of e-waste from non-functioning analogue receivers and transmitters. There has to be a policy about what to do with non-functioning analogue radios and transmitting equipment. This has to be a genuine policy where parts can be recycled and toxic compounds prevented from entering the environment. Not just landfill!
(1b) I need more knowledge on whether current AM (MW and HF) and FM (VHF) transmitters can be retro-fitted with digital exciters.

(2) Given the DRM is open-sourced, the implementation of the HE-AAC codecs (coders for tx, decoders for rx) is subject to paying a licensing fee to the "Via Corporation". There will be an eventual expiry of the patent, but given that HE-AAC is a suite of compression technologies, source http://www.via-corp.com/us/en/licensing/aac/faq.html it may take a few years until the the whole suite of technologies is patent-free.

Thank you,
Anthony of really exciting Belfield
Commenting on digital radio
19 August 2019 - 6:06pm
I left out a couple of answers at the end of your post.
If DRM30 ie below 30 MHz is used the bandwidth is limited to 20 kHz or less.
For music only one program per transmitter. Maximum for 18 kHz bandwidth is 64 kbit/s For speech stations you can have atleast 2 because you can use a lower data rate, infact, the DRM consortium has specified the latest most efficient compression system xHE-AAC It can produce excellent speech at 12 kbit/s. DRM+ because of its wider bandwidth can have 3 stereo programs as mentioned previously.
You can have near FM stereo quality from a DRM transmission in the medium and high frequency bands! You can also have annoyingly noisy AM reception particularly at high frequency, but replace it with DRM and it is a reliable noise free stereo with the high pitched sound in tact. There is also no phasing effects caused by multiple reflections from the ionosphere.
Commenting on digital radio
19 August 2019 - 4:23pm
Hi John .. thanks for the memory of you .. and Keith Fowles and Frank Rolley, Lesley Smith -- Bruce Rogerson -- a few more slow to seep in but I remember the faces .. as we were! Remember we weren't allowed to play television themes on air because they were the new opposition; disc jockeys played discs; schedules were sheets pulled out of cardboard files by Georgina and copy was typed on paper to be carefully read xx Dell Yates John Knox returns to 4KQ
Secret Squid
19 August 2019 - 3:46pm
Yeah right, until the next time. How many chances has Alan had? Macquarie Media Chairman threatens Alan Jones with the sack
Anthony The Koala
16 August 2019 - 9:57pm
Dear StJohn,
Thank you for your reply.

You have confirmed what I said about using lossy compression files in the transmission/reception chain sounding poor.

Thank you for elucidating on the number of 'services' on one DRM channel being three. If two DRM channels can fit onto one FM frequency, given one FM frequency occupies 200kHz, then one DRM channel is 100kHz. It follows that in the AM band typically 1602 to 522 khz has a bandwidth of 1122kHz can fit approximately 10 DRM services. On the FM channels, 108MHz-88MHz = 20Mhz, which gives approximately 20/0.1 = 200 theoretical DRM transmitters. With 3 services per DRM transmitters, that's the equivalent to 600 DRM services. Theoretical because that does not take account of any co-channel interference whether it's on MW or VHF.

HOWEVER, I do note that with DRM and DAB+ transmissions, the same frequency can be used in different areas PROVIDED that all DRM and DAB+ are synchronized using accurate clocks. Synchronization shouldn't be hard because atomic clocks have been used in broadcasting for decades.

My calculations were based on the third paragraph of three programs on one transmitter, NOT the fifth paragraph, where you say that one can fit 6 DRM channels on one FM channel. Please clarify the 3 channels and 6 channels distinction.

Nevertheless, that does not account what for what is final government policy on spectral allocation of DRM services.

One question I would like to ask you is when the DRM signal is on MW or SW bands and due to the properties of the ionosphere such that MW and SW signals skipping long distances is: what is the quality of the received signal over long distances? In addition is there enough error correction information sent with the DRM signal that the recovered signal at the receiver is 'perfect'?

I noted in your previous answers (plural) that DRM has the facility to transmit pictures and text. The questions about pictures and text services raises non-engineering questions but economic: will the radio stations be able to afford providing pictures and text services OR will the radio stations want to monetise and and let other parties pay to use the text and pictures services. A corollary to auxiliary text services is the teletext service, text services on analogue tv as well as DVB. Teletext services providing news, weather, market information was abandoned by the Seven network nearly 20 years ago. The justification for the abandoning of teletext services was that such information was available on the web! Similarly the potential of DRM to provide text and picture services, one asks will it be utilized when the information is available on the web, especially the radio station's web page.

REGARDLESS of technology: whether DRM or DAB+ or web pages, it is an issue for the broadcaster to keep information up-to-date. For example, a former 2UE personality who left 2UE nearly three years ago is still publicised on a rural radio station's web page http://www.hayfm.org/wp/show/stuart-bocking/ . Nevertheless, I do note that DRM's capability to send pictures and text - regardless of DRM or WEB technology, the information needs to be up-to-date.

I must disagree with you about the alleged 'exaggeration' of the use of the FM band. My description of the FM band is EXACT. Yes I am aware for example that VHF FM bands are not the same world wide. For example Japan's VHF FM band is between 75MHz and 95MHz. I was talking about the 88MHz to 108MHz band as used in the Australian market place. All my 88MHz to 108MHz FM receivers can receive frequencies beyond this band. There are services used below 88MHz for example in Sydney for multicultural languages such as Campbelltown's Spanish language station "Radio Austral" 87.6MHz, dance tracks on "Raw FM" to name a few. Source, https://www.acma.gov.au/-/media/Licence-Issue-and-Allocation/Information/Word-Document/High-power-and-low-power-radio-open-narrowcasters-programming-and-broadcasting-data.doc?la=en - definitely not an exaggeration.

In addition, though the MW AM band is officially 522kHz-1602kHz, there are radios sold and marketed in Australia that have its AM band go to 1701kHz. Pioneer A/V receivers, for example VSX-932 and Toyota Camry's radio goes to 1701kHZ to name a few. You can receive in Sydney "The Voice Of Charity" on 1701kHz.

An observation, this is not numerology. Nevertheless, without mathematical proofs, adding the digits of the frequency of a radio station, if divisible by 9 is indicative of a 9kHz-spaced radio frequency. To illustrate for Sydney frequencies, RN on 576 kHz, adding the digits 5+7+6 =18 is divisible by 9. Another example 1701kHz, add the digits, 1 + 7 + 1 = 9, is divisible by 9. One final example 2GB at 873kHz, 8 + 7 + 3 = 18 which is divisible by 9.

One final point. I agree with about the carrier in an AM mode being wasted. I already stated that the carrier remains at a constant level regardless of the amplitude of its side bands.

I thank you for enriching the public at large about the capability of DRM. Please clarify whether a DRM transmitter can carry 3 or 6 signals on one tx, and the quality of a decoded DRM signal over long distances especially on the MW and SW bands.

Thank you,
Anthony of exciting Belfield

Commenting on digital radio
16 August 2019 - 5:23pm
Hi All,
Because Macquarie isn't doing very well,i think they should get rid of Macquarie's Sport radio station in Melbourne that replaced Magic 1278.Magic was a great station and lots of people liked listening to it, particularly older people as they liked the music. Magic is really missed and I think that now would be the perfect opportunity to bring it back.
From Jono and ben
Macquarie Media struggles in a difficult market
16 August 2019 - 12:43pm
Knoxie sounding as good as ever on air, and a separate (windowed) booth for the newsreader at the new studios. Better than the "broom cupboard" at Stones Corner! Did they use the news intro with his v/o in it "also on iHeart radio" etc? John Knox returns to 4KQ
Peter Lewis
16 August 2019 - 10:36am
If I want all music, I'll use Spotify. Seems like they have totally given up! Grant Ed and Ash make way for more music at 2Day
16 August 2019 - 10:35am
Colin Tyrus and many other highly respected journalists are well remembered for the establishment of this great news network. NewsRadio is 25 years old
15 August 2019 - 11:39pm
Many AM stations use processors to try and sound like FM by boosting the high frequency audio because of the very poor high frequency response of AM receivers. This will particularly affect the SBR signal. X Digital in Perth only transmits music and some advertising but not much speech. There is plenty of bass.
The problem for broadcasters is that they can preview MP2, MP4 files and they sound fine, but once transmitted are poor sounding regardless of the bit rate.
As far as India goes, India does not have its population evenly distributed. The Government is trying to cover the whole of the country because it’s All India Radio is the only broadcaster allowed to transmit news and current affairs. They do separate the networks like the ABC local radio does. There FM commercial broadcast industry is tiny. http://www.asiaradiotoday.com/news/drm-association-radio-operators-india’s-agm shows that DRM+ is likely because it can transmit 3 programs on one transmitter. Two DRM+ transmitters can fit into a single FM channel. A main driver for DRM in India is the Emergency Warning System will save millions of lives from the floods of the dual monsoons per year.
As far as cars goes, they have only just started installing DRM in cars and have done it to 1.5 million cars in 18 months and they have only just started. An app has been written for the FM tuner in most Android phones which are much more popular than iphones.
The ACMA has already stated that they are only converting the remote and a few country AM licences to FM as the band is too crowded elsewhere. You can fit 6 DRM+ audio programs onto one FM transmission channel.
As far as Australia goes the cost difference between FM and DRM+ is no where as big as you claim as the single transmitter is used for both of each broadcasters’ programs. The only difference is the modulator and a content server to combine their pair of audio programs to fit into one digital stream. They can add coloured pictures for advertising and could also radiate an electronic text “newspaper” using Jounaline.
So, the cost is reduced because the AM transmitter is switched off as well as the FM transmitter. It can be replaced with a DRM+ transmitter of 1/ 10th of the power for the same coverage area. In remote areas such AM transmitters can be modified to DRM, however there is currently one commercial station on High Frequency (Short Wave) which can economically cover large remote areas. Converting it to DRM will give good stereo sound and it is easily tuned.
Your comment about tuning ranges is exaggerated. FM radios tuning below 87.5 MHz Lower FM frequencies were only used in Japan and the USSR. USSR is now testing DRM+ at a frequency around our analog TV channel 2. All digitally tuned AM receivers are selectable for 9 kHz spacing for 531 – 1602 kHz or is 530 – 1700 on 10 kHz spacing which is only used in the Americas. Much of Europe has no AM at all. No mobile phones virtually no DAB+ radios will receive AM at all.
Over 67% - 100 % of the power of an AM signal is wasted in the carrier. DRM does not have a carrier resulting in drop in electricity consumption. It uses COFDM just like our digital TV.

St John
Commenting on digital radio


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