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This article, which covers Internet & DRM, is probably unhelpful to an Australian audience and quite subjective.
While I do like reading opinions from other engineers, Alan is probably on the fringe of most of your readership these days.
Most commercial networks are investing heavily in internet delivery, and DRM never has a commercial future given the decades of investment into DAB+ by the industry, auto manufacturers, and consumers.
First I will discuss being ahead of our time and an observation of ABC Classic FM and its DAB+ service.
Being ahead of our time:
I am a fan of Mr Hughes (Mr St. John) and when it comes to technical standards in the broadcasting industry, he is second-to-none. I have learned a lot about the technical standards of DVB from Mr Hughes, for example https://radioinfo.com.au/news/acma-offering-vacant-fm-frequencies-wa - see comments on DVB.
While I agree with the other "Anthony" that "...most commercial networks are investing in internet delivery.....industry, auto manufacturers and consumers" and "...DAB+" it does not negate the fact that people are prepared to spend more disposable income on IP data plans. IP data plans can be expensive especially with VOD and it is prohibitive for people on low incomes.
Unless one wants to listen to stations outside the particular person's licence area such as regional or interstate or international or IP-exclusive delivery of broadcasts, I don't see the point of listening to one's local electromagnetic spectrum delivered radio station via my mobile phone.
That's unless reception is poor or one is travelling in road and train tunnels which offer online IP delivery rather than re-broadcast transmission facilities.
Mr Hughes talks engineering common sense when it comes to the delivery of signals more efficiently and packing more information within a confined spectrum allocation. DAB+ and DRM/DRM+ have been discussed by him not only on this site but on the drm.org site. Mr Hughes has also submitted comprehensive reports to the Parliament of Australia regarding SW broadcasts
Unfortunately, engineering common sense does not necessarily mix with government and industry policy direction. Current policy by the ACMA and radio industry is to convert AM regional stations to FM. DRM/DRM+ has not been fully considered by regional broadcasters despite DRM/DRM+ covering a greater distance, having high FM-quality stereo sound, Journaline text, image delivery and emergency radio wakeup-the-radio alert.
Let's not forget that the biggest market for DRM/DRM+ services is India.
Unfortunately, government and industry direction may not make sense when the truth of the engineering facts are bypassed.
An analogy in Australia was in 1957 when there was a lack of interest in FM broadcasting. It was 1961 when mono compatible frequency division multiplex signalling of FM broadcasts were approved by the US's FCC. Note that Mr Edwin Armstrong, was experimenting with the transmission of multiple signals by FDM in the 1930s, source https://en.wikipedia.org/wiki/FM_broadcasting#Stereo_FM .
It's 60 years later that the radio industry in Australia wants to convert to FM. There were attempts by the AM stations to convert to FM long before 2Day and MMM and the exhorbitant conversion licence permits in the late 1980When 2SM was located at 186 Blues Point Road North Sydney, their studios were equipped with stereo equipment and wanted to convert to FM.
The lesson may well be if one is a sole voice even with the most technologically-developed hardware and knowledge, it may well be hard to convince or lobby the government.
The result is that current policy in Australia is for conversion to FM, DAB or online delivery of audio and video services despite DRM/DRM+ offering more.
Hence I disagree with the other "Anthony" that Mr Hughes is "...on the fringe..." when what Mr Hughes mentions is the engineering truth. But like the little interest in FM radio in 1957, there is little interest in today's DRM/DRM+ . This is because the current government and industry policy is convert to FM, utilise DAB+ and internet delivery. That is despite DRM being adopted in India.
Delivery of ABC Classic FM and ABC Classic via DAB+.
I have listened both the FM and DAB+ version of ABC Classic.
I stand to be corrected, my perception of listening to the FM version of the ABC classic service seems to sound more spatially stereo than its DAB+ version.
My only explanation is that the demux circuit of the FM receiver is not perfectly decoding the L and R channels resulting in a phase difference between the L and R decoded signals.
Could the phase imperfections of the L and R signals from the FM receiver's demuxer give the FM radio its more spatial sound than its DAB+ decoded signal?
Thank you,
Anthony, of observing market forces and interests, Belfield
Anthony,
Every 8 years the telcos switch off their oldest mobile technology making everybody buy new phones. Why then has radio continued with AM from 1920 and FM from the 1950's?
The telcos, streaming companies and podcasting companies have been trying to get viewers and listeners to use their services for their own financial gain. They use statistics like a percentage increase in traffic rather than absolute proportions of the audience which is a very different picture. Broadcasters should take them on in this battle. As you agree that broadcasting is more efficient than using broadband which is useless in emergencies.
In Europe from the start of this year all new cars have to have a digital terrestrial radio installed. Since there are now software designed radios, it is easy to combine DAB+ and DRM programs into its single receiver chip which are available now. The digital processing is virtually identical, except the xHE AAC audio compression is even more efficient than that used in DAB+
Radio needs to digitise because broadband can carry pictures and text to keep up. Most broadcasters do not promote existing DAB+ broadcasts, which if analog was switched off could save a lot of money. Unfortunately the 200 MHz band used by DAB+ is unsuitable for country areas because it can only cover small towns and will even need repeaters on major roads leaving the rest of the licence area without signals. India is now covering 600 million people with high power DRM, they have 3 million cars which contain DRM receivers included in the new price and this number is rapidly rising.
DRM is the newest digital broadcasting standard and can digitise the areas above right through the whole continent. With the removal of many journalists from regional Australia's TV and print media, the Jounaline feature will allow commercial and ABC local radio to broadcast stories like a newspaper at low cost. Every broadcaster only needs one transmitter per coverage area.
Dear Mr St. John,
Thank you for averting me to the recent video at https://youtu.be/cJgH-CYQzHg and the link to the SDR app for mobile phones at https://youtu.be/cJgH-CYQzHg .
From the video, it shows how the infotainment system can accommodate AM, FM and DRM reception. It is in the same way that in Australia that cars today have AM, FM and DAB+.
Given that SDR ('Software Defined Radio') is the latest technique of decoding any mode of broadcast, whether AM, FM, DSB, SSB, DSB, DAB, DAB+, DRM and DRM+, then it should be no problem to incorporate any modern radio receiver whether tabletop or car infotainment to incorporate all kinds of demodulation of signals.
Gone are the days when 'old' receivers had diode detection for AM and ratio detectors for FM. One chip operated by an SDR software program can demodulate all kinds of signals at all kinds of frequencies.
As discussed before, one could demodulate any kind of signal using SDR and a USB TV dongle. The received signal can be downconverted to a frequency that can't be handled by the USB TV dongle.
The "Starwaves" DRM receiver is another example how a mobile phone can decode SDR signals, https://starwaves.com/starwaves-drm-softradio-app-for-android-now-available/
With the economies of scale, the production of SDR receivers using one chip will be cheaper in cost than purchasing an AM/FM receiver made from discrete components which are so ubiquotous today.
It is likely that the government and industry policy of converting regional AM to FM is based on the ubiquotous and 'cheap' purchase of AM/FM receivers with the result that DRM/DRM+ is not considered.
So if the economies of scale make the production of SDR radios cheaper than radios made with discrete components, will DRM/DRM" be considered as a method of transmission of programs in regional areas?
In addition, the flexibility of SDR's capability of decoding any encoding system at any frequency, would result in no problem in DRM/DRM+ being decoded at any frequency whether MW, SW and VHF.
But don't expect DRM/DRM+ to be regularly used at the moment. If the economies of scale are that SDR receivers are cheaper to produce than AM/FM radios built from discrete components. This is especially so if the SDR receivers in a future market will have the facility to decode not only AM, FM, DAB+ but also DRM/DRM+.
Then will these future SDR radios have all the broadcast systems in place or only have a subset, for example radios with AM/FM only, or AM/FM/DAB+ only or AM/FM/DAB+/DRM/DRM+? In other words, with the potential to decode any kind of signal at any frequency, will the receiver manufacturers be cheapskates to only offer a small subset of demodulation techniques?
Thank you,
Anthony of thinking Belfield
Anthony,
This video has just appeared. https://youtu.be/cJgH-CYQzHg
Note the frequency is in the medium frequency band. Try broadcasting that musical instrument on AM!
That car is a stock standard Indian Suzuki. They are now at the stage that they are starting to sell DRM to the community.
The Indians don't have much FM radio particularly commercial and they are now trialing DRM in the FM band. It will work with existing DRM radios although the older ones may require a software upgrade.
https://starwaves.com/receivers/ , https://www.drm.org/products-2/
In particular https://starwaves.com/starwaves-drm-softradio-app-for-android-now-available/ There used to be an LG phone with DAB+ but it has gone out of production.
The Indians have 35 high power DRM transmitters up to a million Watts. Our largest is 50 thousand Watts, however if you transmit DRM the output power drops by 50 %. Remember that between 67 - 100 % of the AM radiated power is the carrier which carries no sound.
Gavin,
India has a population of 1 300 million and we have a 25 million. Indonesia with it's 9,000 islands has a population of 276 million are both using DRM South Africa pop 60 million has adopted DAB+/DRM. The Brazilians 221 million also want to use it but have huge Covid problems. DRM will work on all broadcast bands which are used by AM, HF, FM but also band 1 which we used to use for TV channels 0 - 2. This is a worldwide standard. DAB+ is only used in the EU, UK and may be used in South Africa. HD radio is only standardised in USA and Mexico.
There are single chip DAB+/DRM/FM/AM receivers using SDR technology which is used in vehicle infotainment systems.
I would like to remind those who think FM is the best sound it has its own quality issues.
1. to combat the hiss inherent in FM transmission the high frequencies are boosted prior to transmission and the receivers reduce the high pitched sound by the same amount (Pre-emphasis, De-emphasis). Most FM broadcasters use audio processors which measure the sound level in 1/3 octave bands and boost the level is it is low. With pre-emphasis it will mean that less high frequency boost can be used on high volume sound otherwise the transmitter will be overmodulated which would cause interference to other FM broadcasters.
DRM, DAB+ and AM do not use pre-emphasis leaving cymbal crashes to retain their "sharpness".
Weak signals cause the receiver to blend the left and right channels making the signal become mono. Digital systems give you the quality of the system design or nothing. Hiss and noise is non-existent.
Unless the FM receiver is fed with an outdoor directional antenna (like a large outdoor TV antenna) any reflected signals which are common between tall buildings it causes an increase in distortion and a reduction in separation.
I also assume that the receiver uses 50 microsecond de-emphasis and not the USA's 75 microsecond de-emphasis. This causes dull sound regardless of the volume of the signal from the studio.
For the record the problems with AM are; no stereo, lack of high pitched sound, higher levels of distortion, high noise levels particularly from arcing sources and expensive because between 67 % - 100 % of the transmitted signal contains no sound and large transmitter site area which can be expensive. There is also no ability to carry digital metadata for images and text.
Whilst DRM is probably the best technical solution for broadcasting in regional Australia, it will be a brave decision to move to that method and force the audience to buy receivers which have little usability anywhere else in the world.
Unlike DAB, where there's a worldwide market for cheap receivers and hence a (relatively) low cost of entry for the consumer, DRM receivers would likely have to be built specifically for the Australian market. With a small potential purchasing base and consequently large cost per unit sold, you'd be setting us up for an expensive, bespoke system that would be very difficult to market to the listeners.
Unless I am mistaken, Band I is used for DAB+ whereas Band II used for existing FM transmissions 88-108MHz. I thought DRM + is meant to be used using existing FM stations in Band II suitably upgraded.
Only recently ABC has strated trialling DRM30 for AM on 747 which probably will be even more sutiable for full regional broadcasting in such a vast country.