FSK Modulation and Demodulation

[@AllElectronicsChannel]

Become a Patron to support the channel: patreon.com/allelectronics

[@dandreseymour3956]

Great video. None of the other sources I've come across talk about the timing and frequency correction loops. This was just what I needed.

[@AllElectronicsChannel]

Thanks!

[@danielvogel7248]

who's watching this genius in 2024? thanks Greg, you are the best!!

[@AllElectronicsChannel]

S2 S2

[@jakubniemczuk]

That was a pretty solid and straight forward presentation. Great work!

[@AllElectronicsChannel]

Thank you!

[@kapilrthr34]

Sir, you are a saviour..a big thanks from India👍👍

[@ahmedgaafar5369]

Gregory ..you are really a talented teacher...i have read a lot of books in communications and saw hundreds of videos from the Gurus ...and yet you are the best without any doubt....just a little note,,,, FSK sync can also be done by a matched filter that synchronizes with a chirp signal that preludes the message data stream ,of course the chirp must be added during the transmission....but hey this video is no different than your other excellent videos...well done...and in your words... it is really beautiful.

[@AllElectronicsChannel]

Thank you my friend!

[@mikegofton1]

Very good explanation relating mathematical models to implementation.

[@AllElectronicsChannel]

Thank you! Welcome to the channel

[@MR-fs2pc]

Awesome video, once again a pretty complex subject presented in a clear and engaging way. Makes me want to try and build one 😉

[@AllElectronicsChannel]

Let's build!! I only need 150GB for reinstalling Vivado 🤬😠

[@yakovdavidovich7943]

@@AllElectronicsChannel It is unbelievable how big the toolchains are! I've got my DE0 Nano lying around, but I'd probably have to add another hard drive to install Quartus.

[@AllElectronicsChannel]

Yep!! I Unbelievable

[@MR-fs2pc]

This doesn't look too demanding for a FPGA. I'm thinking about trying it with an Icestick and APIO, should save some space 😆

[@OptiarcAD7190A]

THE BEST YT CHANNEL TO LEARN RF!

[@AllElectronicsChannel]

😵😵😵

[@danielsolis5444]

Super great video as always, lot of learning. Just seeing this topic at school, maybe Ill try to implement it for the lab

[@AllElectronicsChannel]

Nice!

[@prajeeshdev_poonkulanji]

Excellent presentation...

[@AllElectronicsChannel]

Thank you! Cheers!

[@archerkee9761]

This was awesome, thanks!

[@AllElectronicsChannel]

Thanks Archer!

[@bitsnbytes7514]

Wow, that was a truly excellent presentation (love your enthusiasm !). I hadn't thought about the clipping trick (near 20:25). As I understand it, it essentially means that we only need to consider the higher order bit of each input sample, right ? (I'm thinking saturated 8-bit signed values, so either +127 or -128). Because assuming that it is the case, since quadrature demodulators essentially multiply the input signal by a couple of out-of-phase reference signals (sin & cos), maybe we can make these reference signals square as well. So we'd only need 1-bit multiplications, which is essentially what a XOR does (binary input signal XOR higher order bit of two pairs of counters running at F1 and F2, each one shifted by 90° with respect to the other). It's super late here, and I'll have to give it more thought tomorrow but... I can see a bunch of neat optimization opportunities here, both for FPGA and CPU implementations. In any case, you earned my subscribe :-)

[@AllElectronicsChannel]

Haha thanks man! Yep, I nice trick is to use 4x oversampling.. Think of a sine/cos sampled 4 times per cycle. It will become a stream of 0 1 0 ‐1... So this simplifies the multiplications a lot, needing only a mux that switches between the signal, 0 and the signal inverted. The sin/cos relations will simplify to two streams 90deg out of phase! 1 0 -1 0 0 1 0 -1 I use this trick on a Speech Processor I designed, I have a video here on the channel, take a look 🙂

[@bitsnbytes7514]

@@AllElectronicsChannel 4 x oversampling because it matches the length of the quaternary vectors [ 1 0 -1 0 ] (sin) and [ 0 1 0 -1 ] (cos). That's just brilliant.

[@johnaweiss]

4:36 Is the energy detector circuit typically the same circuit as an RSS detector? Or will it operate at a different voltage scale or input impedance than an RSS detector?

[@AllElectronicsChannel]

Yes, it can be very similar.. of course, for dsp it is just the signal squared

[@skepticengineer6482]

great presentation! i wonder, is the explained method the principal of how a PLL works? or a freq discriminator?

[@AllElectronicsChannel]

No.. I have videos about PLLs here on the channel!

[@SandeepKumar-jj7zi]

Nice, So PSK too has spectral leakage like discrete FSK ?

[@AllElectronicsChannel]

Yep! For commonly "bitstream" is filtered with a root raised cosine or gaussian filter to control the pulse shape/leakage

[@johnaweiss]

20:48 "pin" of the FPGA?

[@AllElectronicsChannel]

Yep!

[@johnaweiss]

So, a pin on the FPGA which You have programmed as the detector pin.

[@odissey2]

If the FSK signal has no noise and 3V in amplitude, then yes.

[@omsingharjit]

how led signal strength Meter works in old radios ?

[@AllElectronicsChannel]

I don't know!

[@omsingharjit]

@@AllElectronicsChannel Nice

[@phillipneal8194]

Wow ! I gotta think about this. I only need an fpga to make an fsk receiver !!! Even a 4fsk receiver like for WSPR ?

[@johnaweiss]

How can there be frequency offset or drift if xmt and rcv are identical transceivers running identical crystals?

[@AllElectronicsChannel]

It is never equal.. different temperature, ppm accuracy...

[@cjlvossen]

Would be nice to do a follow up on a real FPGA implemention. Great contant!

[@johnaweiss]

Doesn't the time-sync circuit add latency? It adds parts and complexity. Instead, couldn't the xmtr send a clock-sync code at the beginning of each packet, and eliminate the whole Gardner/PIC?

[@AllElectronicsChannel]

That is one way of doing it, for packet transmission. For continous data streams you need to constantly correct the clock. But, event for packets, some detection circuit will be needed

[@johnaweiss]

@@AllElectronicsChannel Event?

[@AllElectronicsChannel]

even

[@mhmtsrml]

What is the program, please.. How can i do it?

[@AllElectronicsChannel]

It was Octave.

[@aayush_deo_ranchi]

can the integrator be made from 555 timer

[@AllElectronicsChannel]

It depends on what you are trying to achieve.

[@AmirNaserGhafourian]

TNX

[@_wave64_]

Wow, Fourier transformation seemed like something only PhD people could understand, until this video.

[@AllElectronicsChannel]

Hahahahahahaha 😎😎

[@jeremyclark3843]

p̶r̶o̶m̶o̶s̶m̶ 🤔

[@y_x2]

What a complicated way to decode FSK. It was invented in the 1930... when no computer existed. The analog circuit used to decode FSK is very simple!

[@AllElectronicsChannel]

😜😜😜

[@odissey2]

Yep. Strangely enough, the analog decoding of fsk is way simpler on a transistor level. To decode a 100kHz modulation it will take a 1GHz processor

[@shamilniftaliyev]

Very good content, keep it up! (but I should admit your English accent is like a torture)

[@AllElectronicsChannel]

Hahahaha! Thanks