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Does anyone else like FM?

OK, I think I understand that, how far the carrier frequency deviates back and forth within its bandwidth determines loudness and how frequently it is deviating is the pitch. It's a little hard to visualize. I don't really understand exactly how the musical signal modulates the carrier frequency or vice versa, but I don't guess I need to know lol.
FM modulation is most simply done with a voltage controlled oscillator, i.e one where the frequency is dependant on a voltage. A Varactor diode changes its capacitance depending on the voltage across it, so if that diode is used as a capacitor in an oscillator circuit, then the frequency will deviate depending on voltage, so can be used as a FM modulator.

S
 
It's a little hard to visualize.
There is some interactive visualization on desmos:
You can change:
  • w_m - frequency of the baseband / modulating signal
  • A_m - amplitude of the baseband / modulating signal
  • k_w - sensitivity of the frequency modulator
  • A_c - amplitude of the carrier / modulated signal
  • w_c - frequency of the carrier / modulated signal
EDIT: although it would be better if it also showed w_delta - how far the carrier signal deviates from its central frequency: https://www.desmos.com/calculator/vpbl5hxmv9
 
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There is some interactive visualization on desmos:
You can change:
  • w_m - frequency of the baseband / modulating signal
  • A_m - amplitude of the baseband / modulating signal
  • k_w - sensitivity of the frequency modulator
  • A_c - amplitude of the carrier / modulated signal
  • w_c - frequency of the carrier / modulated signal
See, as much I'd like to have deeper understanding of electronics and physics, I soon get in over my head with the math it's largely based upon and it reads like Greek to me :D.
 
FM modulation is most simply done with a voltage controlled oscillator, i.e one where the frequency is dependant on a voltage. A Varactor diode changes its capacitance depending on the voltage across it, so if that diode is used as a capacitor in an oscillator circuit, then the frequency will deviate depending on voltage, so can be used as a FM modulator.

S
Thanks I was wondering how the music signal frequency and intensity modulates the carrier frequency and I assume it's the intensity and frequency of the music signal's electrical field.
 
See, as much I'd like to have deeper understanding of electronics and physics, I soon get in over my head with the math it's largely based upon and it reads like Greek to me :D.
I assumed your visualization comment was about the relation between amplitude and frequency of the baseband signal and the look of the FM signal. I posted the link with that in mind, not for the math. Just to see how the FM signal (blue) changes when you change the frequency of the baseband signal (red):

fm.frequency_change.png


or the amplitude of the baseband signal:

fm.amplitude_change.png
 
I assumed your visualization comment was about the relation between amplitude and frequency of the baseband signal and the look of the FM signal. I posted the link with that in mind, not for the math. Just to see how the FM signal (blue) changes when you change the frequency of the baseband signal (red):

View attachment 420903

or the amplitude of the baseband signal:

View attachment 420904

Yes that does help visual how changes in the frequency and amplitude of the music signal changes the FM signal. Although it's still hard to see the music amplitude/loudness deviating the FM frequency and the music frequency dictating the frequency of the deviation as I understand it was explained earlier in the thread. On the one hand, focusing on the graphs' y-axis the graphs sort of seem switched or at least that changes in music frequency and loudness impart the same change to the FM signal. But on the other hand, focusing on the frequencies, I can see in the graphs how higher music frequency deviates the FM signal frequency more often, and higher music amplitude deviates the frequency of the FM signal a higher amount. So looking at it the that way it works as a visual.
 
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On the one hand, focusing on the graphs' y-axis the graphs sort of seem switched or at least that changes in music frequency and loudness impart the same change to the FM signal.
Not sure I follow. y-axis is amplitude and in frequency modulation the amplitude of the carrier signal (i.e. the FM signal) does not change, it doesn't depend on the baseband signal (i.e. the music) at all.

But on the other hand, focusing on the frequencies, ... So looking at it the that way it works as a visual.
Well, yes, it is "frequency modulation", so focusing on frequencies of the FM signal it the way to go :)
 
Not sure I follow. y-axis is amplitude and in frequency modulation the amplitude of the carrier signal (i.e. the FM signal) does not change, it doesn't depend on the baseband signal (i.e. the music) at all.


Well, yes, it is "frequency modulation", so focusing on frequencies of the FM signal it the way to go :)
Not sure I follow. y-axis is amplitude and in frequency modulation the amplitude of the carrier signal (i.e. the FM signal) does not change, it doesn't depend on the baseband signal (i.e. the music) at all.


Well, yes, it is "frequency modulation", so focusing on frequencies of the FM signal it the way to go :)
Maybe I should've said focusing on the x-axis and the space between the vertical lines., then imagining the carrier frequency deviating per music amplitude. But I'm just confusing the issue, so forget that :) . Focusing on the frequencies of the FM signal makes it clear. But I am unclear how frequency can change without altering its amplitude, but don't want to cause more confusion.

Not to get too far off scope, now FM signal strength is really just the strength of the FM signal's electrical field and not really related to frequency or amplitude. So a strong FM signal would look the same it would just have a stronger electrical field, right? And for that matter, the music signal of higher amplitude doesn't really look taller in reality, its electric field is just stronger?
 
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I work (as side job) on a local FM station, and the signal gets very compressed with multiband compression to have the strongest signal possible within the limits of the broadcast antenna (and it's regulations). Most if not all stations also send their music stream in compressed formats (in best case high resolution, mostly not) to their antenna's. That is everywhere the same altough some stations use lower bitrate and higher compression than others. They use specialised devices for this like this Orban Optimod 5750HD to do the processing.
1736834210791.png


Very few don't use this, even classical music channels do use big ammounts of compression. Luckely the local classical broadcaster here (Radio Klara) use very conservative settings so we got still a lot of dynamics in the music But i heared other classical channels that smash the whole dynamics of the music away and so it sound like sh**.
 
i think in my country they simply take the very compressed signal, encode it low bit rate and send it to the internet, sounds awfull.
content of these stations isnt mine anyway.
only radio stations with real good quality are soma.fm, also content is nice for me.
they have AAC 128kbit for all their streams and some have 256kbit mp3.
i would say they dont touch the dynamics much if at all, beeing a online station only there is no need for it anyway.
 
I work (as side job) on a local FM station, and the signal gets very compressed with multiband compression to have the strongest signal possible within the limits of the broadcast antenna (and it's regulations). Most if not all stations also send their music stream in compressed formats (in best case high resolution, mostly not) to their antenna's. That is everywhere the same altough some stations use lower bitrate and higher compression than others. They use specialised devices for this like this Orban Optimod 5750HD to do the processing. View attachment 420934

Very few don't use this, even classical music channels do use big ammounts of compression. Luckely the local classical broadcaster here (Radio Klara) use very conservative settings so we got still a lot of dynamics in the music But i heared other classical channels that smash the whole dynamics of the music away and so it sound like sh**.
I imagine some dynamic compression is necessary of a digital music source especially classical to fit FM's lower dynamic range. But I wished broadcaster would at least utilize FM's dynamic range. And what's the good excuse for not using high bit rate even if they're uploading the music across town to the transmitter? And it's not like most stations have an extensive playlist.
 
Does anyone else like FM?

Simple answer from me is yes…

I don’t think it sounds better than internet radio on my network player, only the strongest of signals don’t hiss in stereo, but it has a bit of a novelty factor about it in todays world and the ease of just switching it on and tuning the dial to me is more appealing than scrolling on apps.
Yes, I fully agree!
For my home I use an NAD Monitor Series Stereo Tuner 4300 (digital tuner with a rotary tuning knob that has a bit of weight and can be spun like the old balanced analog tuning knobs with the same effect) that has had the internal audio circuits revised for a more linier (audiophile?) audio output. The reception circuits have also been modified for DXing.
I also us a SONY FM/AM Digital XDR-S3HD for HD channels.
Both of these are connected to my chimney mounted:
Magnum Dynalab ST-2 Vertical, Omni-Directional, ½ Wave Antenna set up at 25 Ft. above the ground.
I can easily get low powered stations (such as the only Jazz station within range) at 85 miles away. More powerful stations I can get out to a bit over 100 miles away.
But you must match your antenna capability with your tuner to do this:
It is possible the tuner does not have the selectivity necessary to deal with the higher gain provided by the ST-2.
My reception ability looks like this:
Radar-FM (7).png

The next step is to add this:

MD 205 Signal Sleuth FM Amplifier​

MD 205 FM Amplifier

  • 3 Stage FM tuner amplifier
  • Unique in the world because it only amplifies the station you are tuned to up to 30 db.
  • You can also decrease the signal by up to 30 db. If you are experiencing overload from a close station.
  • Steeply rejects by 18 db. Per octave all other stations
  • By-pass mode
  • Tuning knob tunes to the station you wish to amplify
  • The gain knob allows you to boost the signal or decrease it.
  • Detachable power cord.
 
FM is limited at around 15kHz and getting fully rid of the noise is hard (as far as I remember at least). So even Soundclouds 64kbps Opus sounds better than FM.
For many of us older folks (or those who were exposed to a lot of loud noise [at 67, with the things that I did both at work & for recreation] I fit both categories): a 15KHz limit is not an issue.
 
That's what I don't understand. If the music is being compressed so it can be broadcasted to playback louder without exceeding some transmitting level, and it is not related to FM signal strength, then what is loudness related to in the broadcast signal?

Anyway, I couldn't detect increased dynamic range on the oldies station that's quieter with the weak mono signal, but I certainly can on the quieter strong stereo signal classical station :p. I realize that's probably due to the music source. Which leads me to think did the FM broadcaster on rock/pop really need to compress the music so much to make it so loud?
If the average signal level is set such that there is plenty of headroom for peaks to be broadcast without clipping them the volume control has to be set higher for normal listening.
Most people don't do this so channels which clip all the peaks off then raise the average signal level sound better.

It is the same as the loudness wars in digital files and the reason why people think efficient speakers are more dynamic. Most people seem to think there is a source/speaker independant "natural" volume control position and tend not to set it high enough for inputs with wide dynamic range, and on classical music those peaks may only happen once or twice in a 20 minute work so many won't notice if they are cut off. Then if they leave the volume control where it was for a pop station it won't sound good, if they just re-set the volume they can enjoy the peaks when they come (if the system is good enough).
 
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I imagine some dynamic compression is necessary of a digital music source especially classical to fit FM's lower dynamic range. But I wished broadcaster would at least utilize FM's dynamic range. And what's the good excuse for not using high bit rate even if they're uploading the music across town to the transmitter? And it's not like most stations have an extensive playlist.
IME FM radio has enough dynamic range for music, better than LP records, for example.
The limit for noise is signal strength and tuner sensitivity, not the fundamentals of FM.
 
I haven't listened to FM in years. All my fav stations died. The remaining ones are advertising channels here in the Bay Area. SQ wise FM definitely not ever set a standard, in my opinion.
Same here, no FM in many years but for someone who grew up in Cologne in the 60s and 70s, 5 km away from the WDR with its dedicated Jazz & experimental grooves channel and the renowned 'Studio for Electronic Music' (first of its kind in the world; K.H. Stockhausen's sound lab) it definitely brings back sweet memories of a kid who listened to those wonderful vibes for hours every single day until he moved out and far away.
On a side note, like many other folks back then I recorded a lot of the material on tape and later cassette tapes and TBH, even with the excellent FM signal strength at my home I don't miss the sound quality of those tapes a bit, to my ears the SQ can't hold a candle to well encoded 128kbit aac we can DL from places like youtube these days.
 
And what's the good excuse for not using high bit rate even if they're uploading the music across town to the transmitter?
Straight from the conspiracy theory department: Two steps forward, three steps back.
When records were the "standard", good cassette decks were expensive.
When CDs became "standard"...they started f*&ing them up, remixing, remastering, brickwall limiting them etc etc so whatever you end up is somehow "less" than before.
Streaming made it even "better": You make selections from the internet juke-box by feeding it a bag of quarters every month;forever.
...and the chances they are better than the CD version are slim.

in short.. the distance between the final master mix and what becomes available to the consumer keeps increasing.
I've always wondered what the "master" sounds like before it gets sent to be magled up..
 
I imagine some dynamic compression is necessary of a digital music source especially classical to fit FM's lower dynamic range. But I wished broadcaster would at least utilize FM's dynamic range. And what's the good excuse for not using high bit rate even if they're uploading the music across town to the transmitter? And it's not like most stations have an extensive playlist.
I think you're confusing dynamic range compression with bit rate compression.
The audio has its dynamic range compressed to sound louder, and with multiband compression, to have more 'punch' and to create a signature sound for the station. The link from studio to FM transmitter is either analogue, in which case there's no extra compression, or these days usually digital, but using either FLAC, or high rate lossy like 320k AAC or NICAM so effectively transparent.

S
 
I think you're confusing dynamic range compression with bit rate compression.
The audio has its dynamic range compressed to sound louder, and with multiband compression, to have more 'punch' and to create a signature sound for the station. The link from studio to FM transmitter is either analogue, in which case there's no extra compression, or these days usually digital, but using either FLAC, or high rate lossy like 320k AAC or NICAM so effectively transparent.

S
And the feed to live Internet streams is often taken pre-"Optimod" (or equivalent), so that the Internet stream is potentially less audio-compressed than the FM transmitter stream.

I had a debate with the top tech boss when mild compression was being considered for a classical radio station. I was young and naive and he was wise. Apart from the standard argument that most listeners are in non-ideal situations with background noise and not using HiFi gear, he also quite correctly pointed out that mild compression improved transmitter fringe SNR so people who currently had poor reception would benefit.
 
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