Best sound quality that you, technically, can get from an FM radio signal is..?

[DanielT]

Out of sheer curiosity, what is the best sound quality that you, technically, can get from an FM radio signal?
Dynamic range? Level distortion and noice? Frequency range? 20-20 kHz +/- ? dB?

Partly: Best possible transmitters and receivers?

Partly: How good is the best signal, before it is converted in the receiver?

 

[jae]

~60 dB: http://www.audiomisc.co.uk/HFN/BandwidthBlues/page.html

 

[solderdude]

Out of sheer curiosity, what is the best sound quality that you, technically, can get from an FM radio signal?
Dynamic range? Level distortion and noice? Frequency range? 20-20 kHz +/- ? dB?

Partly: Best possible transmitters and receivers?

Partly: How good is the best signal, before it is converted in the receiver?

When it is stereo the channel separation is limited and the BW is no higher than 15kHz.
Also most radio stations use optimod (a compressor).

FM transmitters for wireless headphones could de better but there will always be noise and distortion.

 

[ZolaIII]

Wide band 16 KHz with a great tuner around 76 dB.

 

[DanielT]

~60 dB: http://www.audiomisc.co.uk/HFN/BandwidthBlues/page.html

Thanks for the information !

I think that was interesting information. About space on the FM band, stereo and mono, and different types of filters.

I'll paste some from your link.

Bandwidth Blues

For stereo, the ‘trick’ is to convey the difference between the L and R sounds by modulating an ultrasonic subcarrier at 38 kHz. In practice, this appears as a ‘mirror image’ pair of components either side of 38 kHz. The above diagram represents this with the blue shape representing the audio information for an example of a mono sound, and the red shapes representing stereo (difference) information. The audio signals are said to be multiplexed together before being used to frequency modulate the transmitted VHF.

A mono receiver simply ignores any components above 15 kHz that emerge from the FM demodulator. But a stereo receiver also detects the extra signals above 15 kHz. It then uses a stereo demultiplexer to combine them with the mono and re-create the required stereo [1]. The system can work very well, but adding on the stereo information in this way can lead to problems which often tend to be overlooked ...

 

[DanielT]

When it is stereo the channel separation is limited and the BW is no higher than 15kHz.
Also most radio stations use optimod (a compressor).

FM transmitters for wireless headphones could de better but there will always be noise and distortion.

Well, that's something to consider. At least if you are younger and can hear a bit over 15 kHz (or 16 kHz bid given by ZolaIII).

OT.
Read two audiophiles who worried that a DAC that dropped 0.5 dB between 19 kHz-20 KHz.

They are, I know, both retirees (over 65 years).

Could not bother with them and explain how it works with age and human hearing. They continue to complain about the DAC. Put the energy on something else, I'm just saying.

 

[ZolaIII]

Nope signal is wide bound aka 16 KHz and I mean really great (vintage) analog tuner. Tell you what it really doesn't matter much above 12.5 KHz (not that much happening beyond).

 

[DanielT]

Nope signal is wide bound aka 16 KHz and I mean really great (vintage) analog tuner. Tell you what it really doesn't matter much above 12.5 KHz (not that much happening beyond).

Ok.

Just a little information over 12,5 kHz? What do you mean? Does the information gradually decrease from 12, 5 kHz?

 

[sergeauckland]

Many of the limitations of FM are at the transmitter end.

Firstly bandwidth is limited to 15kHz with a very steep filter, as it can't be allowed to intrude on the 19khz pilot tone. The transmitter I use is -40dB at 19kHz. Receiver bandwidth is much wider as it has to accommodate the full multiplex signal, then de-emphasise the decoded L&R.

Distortion is around 0.5% at peak deviation, although the latest transmitters can achieve 0.1%. However this is heavily modified by any audio processing like Optimod, where the amount of distortion varies dynamically with frequency and amplitude. Peak clipping is commonplace as it can increase loudness by 1-2dB without it being subjectively too disturbing. CD mastering learnt from FM radio!
Crosstalk rarely betters 40dB, with a perfectly adjusted receiver, and around 30dB more likely. Transmitter crosstalk can be around 55dB, although again modified by the processor.

FM radio transmitting a live concert used to be the highest quality source available to a home listener, but excessive processing to make it usable in cars and on portables have rendered FM now very much a mid-fi source. Internet radio has the potential to be a much higher quality source.

S.

 

[ZolaIII]

90% information contained in recording is below (mids 50%, low 27% highs and uper highs 23%). There are odd recordings of jet or rocket lift-off but seriously I don't think you gonna listen to that (especially not at 115+ dB).

 

[DanielT]

Thank you for your answers and descriptions. I find it very interesting.

Had I lived in the neighboring country, this sound quality regarding FM radio would only have been a theoretical issue.In Norway analogue FM radio
is now only a fairy tale.

An article from 2018.
(translated text)

An effective lobby in Norway made politicians betray the public interest

As the only country in the world so far, Norway has taken the step of closing the FM network to national
terrestrial radio and completely switch to digital DAB +. Given the massive development of online radio and the fact that FM is an established world standard in all 220 countries, this dramatic step has surprised the outside world.

Varför DAB-radio i Norge, men inte i Sverige?

Fakta och debatt om digitalradio, FM-radio och Internet radio och television

www.publicaccess.se

 

[LTig]

In Norway analogue FM radio is now only a fairy tale.

An article from 2018.
(translated text)

An effective lobby in Norway made politicians betray the public interest

As the only country in the world so far, Norway has taken the step of closing the FM network to national
terrestrial radio and completely switch to digital DAB +. Given the massive development of online radio and the fact that FM is an established world standard in all 220 countries, this dramatic step has surprised the outside world.

Varför DAB-radio i Norge, men inte i Sverige?

Fakta och debatt om digitalradio, FM-radio och Internet radio och television

www.publicaccess.se

Oops. No more news and music when I travel in Norway by car? That's really disappointing.

 

[JeffS7444]

15 kHz is the original goal for analog FM radio transmissions.
https://transmitters.tripod.com/stereo.htm
And here's what a very good modern tuner's performance looks like:
http://www.ham-radio.com/k6sti/xdr-f1hd.htm

 

[DanielT]

Oops. No more news and music when I travel in Norway by car? That's really disappointing.

That's how it is

As of 2021, 42 countries are running DAB services.[8] The majority of these services are using the upgraded DAB+, with only the UK, New Zealand, Romania, Brunei Darussalam and the Philippines still using a significant number of (original) DAB services. In many countries, it is expected that existing FM services will switch over to DAB+; so far, Norway is the only country to have implemented an analog switchoff program, having switched its national broadcasters to digital-only in 2017.

Digital Audio Broadcasting - Wikipedia

en.wikipedia.org

 

[DanielT]

15 kHz is the original goal for analog FM radio transmissions.
https://transmitters.tripod.com/stereo.htm
And here's what a very good modern tuner's performance looks like:
http://www.ham-radio.com/k6sti/xdr-f1hd.htm

Well hm, I must say not very well. Then there is the question of where the limit for the audible distortion, the limitation of frequency range lies (which is another discussion) .... and how sensitive one is to it. Of course.

BUT do not curse the darkness, lit a candle! You can still listen to FM radio. a lot of fun and exciting tips on good music. Then you have to take the sound quality for what it is.

But of course nowadays there is so much good radio on the internet. A very nice development.

Lossless radio?

Or rather how good sound quality can be found on internal radio stations nowadays? Best sound quality is ...? Feel free to share and suggest some stations you like (genre does not matter). I listen to this station sometimes, nice Jazz::p https://somehowjazz.com/

audiosciencereview.com

 

[Raindog123]

Out of sheer curiosity, what is the best sound quality that you, technically, can get from an FM radio signal?

Are you asking about FM as a modulation technique (in general), current FM broadcast band, or legacy FM broadcast signal/waveform standard? The answer is different for each… Eg, one can come up with a super-quality FM — high SNR and wideband, by combining multiple carriers — but it will be outside current FM standard/receiver capability…

And in the North America there is this (similar to DAB):

HD Radio - Wikipedia

en.wikipedia.org

 

[DanielT]

Are you asking about FM as a modulation technique (in general), current FM broadcast band, or legacy FM broadcast signal/waveform standard? The answer is different for each… Eg, one can come up with a super-quality FM — high SNR and wideband, by combining multiple carriers — but it will be outside current FM standard/receiver capability…

And in the North America there is this (similar to DAB):

HD Radio - Wikipedia

en.wikipedia.org

Purely theoretically how good with combining multiple carriers? Now you certainly said super-quality so then there is probably more of a limitation in terms of demand (which is hardly likely to be so great nowadays considering DAB, Internet radio) and applicable laws.

There is a lot one can DIY but to try to create many carriers on the FM band. Then comes Mr. Police (in most countries, I think)

 

[DSJR]

Listening to BBC Radio 4 news at 1pm today, the sound went from good to bleedin' awful, depending on whether the announcer was facing the mic or not (easy to hear her turn to one side - to consulkt notes?) and also the linked reporters, one of them sounding as if he was talking into a blanket and another seeming to phone her report in via a peaky phone mic... Much discussion around and about regarding the lack of sound quality on the BBC these days...

 

[Willem]

OK, that is two different stories: one about the way some stations record, and another about the limits to FM technology. As for the latter, I have given up on FM. On balance, I think internet radio often offers a sound quality that is at least as good as FM, if not better, although the imperfections are different from those on FM. So for me the benefits of an almost infinite number of international stations are too large to ignore. And of course, the bit rate will only go up in future.
In the car we now have DAB+, and that is undeniably better than FM on a car radio, and better than the BT stream from our phones.

 

[DanielT]

Much discussion around and about regarding the lack of sound quality on the BBC these days...

Maybe a phasing out of the analogue FM radio is in progress?

In connection with that BBC reduce the service, the quality of analogue FM radio?