Understanding FM #1 - Slow motion FM, frequency deviation, and how FM radio works

Рет қаралды 3,996

Ай бұрын

Welcome to a new series I'm kicking off that is going to take a long look at frequency modulation, how it works, and how to use it. This is a big topic that often gets short-changed in terms of real explanation, so I'm going to take it a step at a time.
In this video I'm going to start slow -- with LFO rate modulation so we can get a sense for what is happening to the Carrier oscillator, and to explore the controls we have and what they do.
Part of this effort as well is to shine a bit of light on the original paper on FM by John Chowning. There's a lot of interesting stuff in there that I never knew about, and I've been programming FM synths since the 80s!
Get ready, we're going deep.
Here's a link to John Chowning's paper: web.eecs.umich.edu/~fessler/c...

Пікірлер: 44

@SousaphoneMusic Ай бұрын

I never realized that fm radio needs a band of frequencies to operate in but that makes so much sense

@SoundVoltage Ай бұрын

@SousaphoneMusic - I know, I never really thought about it before this. And the width of the band? Literally the bandwidth. :)

@fonesrphunny7242 Ай бұрын

Recently found that cool DX7 emulator. Decided to practice FM with a more approachable device first. Now we're here. Maybe off by a week, but still good timing ;)

@CyberBlob69 Ай бұрын

Nice video. FMCW radar is also a nice concept, where the range of the target is related to the frequency shift of the received signal.

@ResonancePeriod Ай бұрын

I really appreciate all the work you're putting into this series!

@murat_buyuk Ай бұрын

awesome. THANKS!

@modalmixture Ай бұрын

I’ve watched several other FM deep dives, but I already have a feeling this is going to be a good one. Strapped in and ready for the journey.

@speed0 Ай бұрын

Since this is meant to be a complete overview of FM, i think its worth clarifying the whole "deviation range" thing. The way it was described it made it sound like all FM needs to have the carrier wave completely in the middle with equal deviation on other sides. FM can be done with the modulator being a unipolar wave which would only raise (or lower) the pitch of the carrier. Plenty of complex oscillators (ie Verbos Complex Oscillator) work this way, so i definitely think its worth noting at some point in the series. Looking forward to the rest of the series and future videos from you in general!

@SoundVoltage Ай бұрын

@speed0 - That's good feedback, thanks. I was going to come back to deviation in the context of exponential FM where the carrier sits about 1/3 the way through the deviation rather than centered -- but I didn't know about the verbos, I'll mention that. Thanks.

@QuimFont Ай бұрын

very smooth and informative. Thank you for planning all of this so well and with such a smart delivery.

@SoundVoltage Ай бұрын

Thank you!

@LeoPerantoni Ай бұрын

Oh yes FM is definitely something Id want you to talk about and here we are!

@NiamorH Ай бұрын

To be honest I think this is a bit quick as an explanation of how FM radio works. It could be interesting to go further into the details :)

@SoundVoltage Ай бұрын

@NiamorH - Maybe I'll do a whole separate video on that. I didn't want to take people away from the synth side of things, but it is definitely worth more than the 60 seconds I gave it.

@timnordberg7204 20 күн бұрын

maybe as an addendum to this series. It would have been cool to hear the carrier modulated with the VO during the FM radio part, though.

@IconOfSin Ай бұрын

I retuned FM filters (ie the RF transmission component) years ago on work experience, never expected EQ knowledge to come in so handy, literally just turning bolts to dial in a BP on a scope. Great idea for a series, looking forward to jumping down the rabbit hole!

@forestine_ Ай бұрын

great explanation, as usual. thanks!

@SoundVoltage Ай бұрын

Glad you liked it!

@meesvandenberg9468 Ай бұрын

so clear!! your channel is a gem

@SoundVoltage Ай бұрын

Wow, thank you!

@user-ng9uc3vu3k 21 күн бұрын

Yes, .. I never knew that FM radio signal's path had a width. I always thought of the signal, like a narrow, single rail .. versus a 3' wide sidewalk, relatively speaking. The FM stations around here .. indeed, they're spread quite far apart on the tuner range, in my location. And Mordax Data, .. what a cool tool. I never considered getting a 2nd one .. but, now I am. .. :)

@oliverb7897 Ай бұрын

Already getting impatient for the next video!

@SoundVoltage Ай бұрын

@oliverb7897 - I'm writing the script for #3 right now, and the demo recordings are all done. Friday, I believe!

@sqwook Ай бұрын

That was awesome, thank you

@SoundVoltage Ай бұрын

Glad you enjoyed it!

@ramalshebl60 Ай бұрын

lucky me, just finished the previous video about cv and analog oscillators, and you uploaded this yesterday! i don't have to wait!

@nickstokes9386 Ай бұрын

Really looking forward to the rest of this series.

@els1f Ай бұрын

This is going to be amazing 😌 You explain things so well that when I THOUGHT I understood them I realize by the end that I didn't REALLY understand them lol✌️

@SoundVoltage Ай бұрын

Wow, thanks! It's going to be fun.

@anicca3179 Ай бұрын

Awesome! Looking forward to the next episodes. Thanks

@SoundVoltage Ай бұрын

@anicca3179 - There should be one either today or tomorrow!

@apeirogonmusic Ай бұрын

Love FM Lets hope this series gets many parts

@SoundVoltage Ай бұрын

@apeirogonmusic - The next one should be out today or tomorrow I hope!

@Probbie Ай бұрын

Very nicely described 😊

@SoundVoltage Ай бұрын

Thank you! Cheers!

@TiniCakes Ай бұрын

i am so excited for this XD

@Beatsbasteln 29 күн бұрын

I still don't understand the thing about the FM radio tbh. Like why does it need FM in the first place? Which problem is solved by applying FM to some music before sending it out there so car radios can pick it up? or is it before or after? what's each stage like?

@SoundVoltage 29 күн бұрын

@Beatsbasteln - It's not really right to think of it as "applying FM before sending it out". Without any audio signal, the FM transmitter would just output a constant sine wave at the frequency of the station -- say 90.3 Mhz. That pure sine wave is modulated by whatever the audio is. It's not something done ahead of time, the transmitter does it on the fly, wiggling the oscillator a little faster or a little slower than 90.3 Mhz depending on the pitch and amplitude of the signal. That is literally what it means to broadcast in FM.

@GillamtheGreatest Ай бұрын

do we get an am radio sidequest?

@SoundVoltage Ай бұрын

Only upon reaching third level :)

@GillamtheGreatest Ай бұрын

@@SoundVoltage xp grindcore lets go

@teebeedahbow Ай бұрын

This is good, but you did the thing that scientifically literate, and especially mathematically literate people do, you jumped from one thing to another too quickly. What is it that FM Radio is really doing? After all, it isn't broadcasting sine tones! I get it about the broadcast width etc, but how does it carry songs by Elton John and The Wu Tang Clan? Not in the same way a DX7 carries sine tones, presumably.

@SoundVoltage Ай бұрын

@teebeedahbow - the two are really very similar in terms of the actual modulation. In the DX-7, you have one audio rate sine wave modulated by an audio rate signal (another sine wave); on the radio you have a much, much higher-than-audio-rate sine wave modulated by an audio signal (Elton and Wu Tang - the crossover we've all been waiting for). Of course the DX-7 turns into audio, which vibrates the air and on into our ears; whereas an FM transmitter wiggles at the electromagnetic field, which is then picked up by an antenna. It's a fair criticism though, and maybe I should come back and do a longer video just on radio -- I didn't want to distract too much from the synthesis side of things, but radio definitely deserved more time. Thanks.

@teebeedahbow Ай бұрын

@@SoundVoltage Thanks very much for the explanation. I really enjoyed your video. I was just disappointed with myself that I could make the jump from FM synthesis to FM radio.