HTML-код
- Опубликовано: 26 ноя 2024
- This video describes how a Pulse Counting FM Discriminator works - it is a unique FM demodulator that doesn't require and tuned circuits like the FM Ratio Detector or Foster Seeley discriminator. It operates by measuring the changing duty cycle resulting from a series or fixed width pulses that are synchronized to the carrier, or IF frequency.
Here is a link to Alan Yates' blog on a discrete FM broadcast receiver made using this technique:
www.vk2zay.net/...
A link for the diode ring mixer (that I promised):
• #167: How a Diode Ring...
And a copy of my show notes:
www.qsl.net/w2a...
![Hunxho - Ball Forever [Official Video]](http://i.ytimg.com/vi/nki9ZTF9Uls/mqdefault.jpg)
I feel like enlightened! As soon as I get an oscilloscope, i will make everything you used here!
I always enjoy your stuff. Teaches me new things and new techniques . Please don't get tired of teaching us.......
Thank you - I won't grow tired of it, just hard to find the time to put together good videos sometimes.
@@w2aew Quality takes time.......but is VERY worth every second....
I agree, I've learned so much watching these videos more than rereading my textbooks sometimes and it helps me in my electronics hobby as well.
I agree
A godlike presentation Alan! You mean you don't have to count pulses. I already purchased a stethoscope!
This channel is pure gold.
By far my favorite engineering youtube channel. I also enjoy the Boom guy, Australian Guy and the Bell Labs Microwave Guy. They all have really educational videos and very practical approaches, but I find this channel the best, none explain things so clearly. Probably the calm voice also helps. When I watch the Australian guy all I hear is screeching.
OK, I'm pretty sure I know who you mean by "the Boom guy" and "Australian Guy"... but can you tell me who "Bell Labs Microwave Guy" is? That sounds interesting, but I'm not sure I'm aware of that channel...
Very elaborate and clear presentation, thanks a lot !
I am interested to study and finally make some pulse-counting detectors, so I watched your clip very carefully. Congratulations! While studying the history of this type of demodulation, I discovered that there were many companies that produced FM tuners with pulse-counting. The undisputed champion is Kenwood, but I also noticed Accuphase, Heathkit and Fisher. Here are some FM tuner models equipped with pulse-counting demodulators: Kenwood 600T (1976), KT-615/815/917 and L-07TII (1979), L-01T and KT-80 (1980), KT-9XG, KT-900/1000/1100 (1981).
Kenwood produced pulse-counting discriminators using discrete components, discrete+some known ICs (TA7060P, SN74LS03 or SN74LS38N, HA1457, NJM4558D) and dedicated/proprietary ICs (TR4010A and TR4011).
Another FM tuners with pulse-counting: Fisher TFM-1000, Heathkit AJ-1510AS .
I hope that these informations will help.
Also, a good source of info is the "Tuner Information Center" at www.fmtunerinfo.com/kenwood.html .
Good luck and be sure you have one more student watching your clips! :)
Best 73s de Cezar YO3FHM
Good information, thank you for sharing.
To the best of my knowledge including the many years I worked in RF, I never came across this type of Discriminator.
Very interesting to me. Thanks again for giving me something to look into.
Kenwood/Trio used it in their last line of all analog tuners (around '79, KT-615, 815, 917). They were so proud of it they printed PULSE COUNT DETECTOR no fewer than three times on the front of the case.
I am a MD physician fro India.amazing video about pulse counting demodulation.vivid as usual
@@bcarlyle7741 Sorry for such a LATE response. RUclips didn't notify me. Thanks for the information. I'll look into Kenwood tuners. I'm still surprised that I never heard of this technique knowing my background.
Very good explanation. I have an old Modulationmeter for AM and FM. The FM-Modulation is measured with this principle, because such a FM-Demodulator is very linear when built properly.
Best educational videos on RUclips! Thank you again.
Another mystery unveiled for me! Thank you Alan, always a great pleasure to watch your videos. I even downloaded every video you posted for me to watch in case YT goes down. I said it before and I have to say again: you are a treasure for us. Thank you, prof. Alan Wolke
Nice to hear someone who knows their stuff and speaks with confidence on a very interesting subject.
What a brilliant demo! This is the type of project that makes me want to get back into RF engineering.
Thank you, for another selfless gift to the world. You are absolutely the world's best teacher on RF design topics.
Best videos on RUclips! Watched this video 3 months ago with the intention of improving my radio building skills. Was my first introduction to pulse generation. As I learned more about PWM circuits, I got side tracked and made a modulated carrier IR circuit and motor control circuit. Eventually, I'll be ready to make a Pulse Counting FM Demodulator. Thanks for sharing and educating us!
waw..., I am always amazed at the clarity with which you can explain every subject you touch upon. Thank you very very much for these videos!
All the best from Belgium!
Thank you for this excellent vídeo, very well explained. Greetings from PY5ZWS , Brasil.
Glad to have you back.
These videos rekindle my love affair with electronics. Thank you w2aew!
Very enlightening. I have a Heathkit AJ-1510a tuner which appears to use such a detector. Integrator/amplifier uses a 709 opamp; I want to see if a better opamp will improve audio quality.
Alan did it once again. I said it once boys and I'll say it again. Pack your stuff because there is one engineer here and it's Alan.
Thanks Alan for yet anotber delightful video. The format is just perfect, finely polished. Nothing needs to be added or taken away. :-)
Every bit of it is enjoyable and the sum makes for a really efficient learning tool.
Knew nothing about RF before I started watching your videos and those of Shahriar/TSP, but I am glad to say that your work paid off. I am now no longer afraid of mysterious looking shielded cans....for the first time last week I had the opportunity to be confronted with the stuff ...albeit to a modest extent....FM radio reception in my 20 year old car was horrible. Car has a preamp sticked to the base of the roof antenna. Yeah, a shielded can ... I thought yeah let's open it see what's inside this thing, maybe I can fix it !
And yeah I was lucky I could fix it... Just yet again a bad electrolytic cap ! LOL
But whatever, point is I was not afraid of opening the can, and took pleasure at studying the board to see how it's put together, armed with all the knowledge you and Shahriar dispense !
Anyway, all this long winded post just to thank you for taking the time to produce such marvelous videos. They are very efficient and enjoyable, extremely appreciated, and as I tried to illustrate above....they actually produce positive results :-)
It takes work to produce such well crafted videos so I don't know how long it will be before you get tired of it, but even if you were to give up tomorrow, I would still be very grateful for all the videos you have done so far ! :-)
I see that you are now past the 100K subscribers, quite a milestone for a niche channel like this one. This means people really see value in your work, so I am hoping this will keep you motivated and that we will be able to enjoy your little gems for a little while :-)
Greetings from Frog land,
Vincent Trouilliez
Thank you - I agree, Shahriar's content is outstanding.
Well, this is quite an elegant solution. Sure I have to build a railroad communications receiver this way. Russian railways use 2.130 and 2.150 kHz FM channels so I could simply build a fine receiver using ferrite antenna with differential RF amplifier IC and circuits shown here. Great job, thank you. 73 de R2ATO!
Thank you for teaching great stuff. One of the best channels.
Correction: THE BEST CHANNEL !!
What a great job! Crystal clear explanation from beginner to expert. Thank you very much also for the link from VK2ZAY.
It'll never be said enough, but thanks for putting up such quality content, man. You've helped me through my undergrad to grad to real world work experience - even if what you've posted is not directly applicable to what I'm working on. The explanation of your content is superb. It's something to emulate.
Thanks a lot Alan. Please don't stop! You make a lot of sailors better aviation electronics technicians!
i always enjoy your stuff!!!!!...thank you for ur help tnx sir keep it up!!!!
Great explanation and demonstration Alan. Enjoyed it very much. Thumbs up
Thank you for producing such great information-loaded videos. ARL 73!
Wow!!! Perfect explained. All your videos are amazing Alan, thanks a lot.
Really you are the best to explain things. It goes straight into mind. Pulse counting technique is really interesting. Thanks for all your efforts in making this video.
I am amazed by your explanation skills. Thank you.
What a great little tutorial. This explanation makes it very clear. Really makes sense now.
Thanks Alan! Nice video! I can't believe that some jerk disliked this video!
I am always looking forward to your videos -- you are the only one where I asked youtube to notify me :-).
It's pity you don't produce videos so often ... I love your explanations! As always superb video! Thank you so much.
I wish I could do more too - just don't have the time. Several hours of work are behind each of the videos, as you might imagine.
@@w2aew I understand hopefully will be more. Please and could you prepare video about noise sources and how to properly measure performance of homemade noise source?
Absolutely exquisite video ! So pumped to go to my own little lab and spend the weekend there ! Really enjoyed this video.
Fascinating. It seems like digital-style circuits with switching are "unreasonably effective". they are still so useful for such an analog, frequency domain problem as FM demodulation.
Very cool, Alan. Appreciate the top notch content for my ride home from work!😊
Hopefully you're not driving!! ;-)
@@w2aew lol, no. Metro North from grand central!
Finally got my TA2111 chip project operating in FM mode. It's been my practice stage to gain experience combining the Osc and RF coils with a ganged capacitor as Alan has suggested. It's been much harder than an AM receiver! I think I'm almost ready to try the pulse counting FM receiver...
Alan, always great stuff. I’ve never attempted to build an FM receiver from scratch, but this method looks so simple.
Works amazingly well for how simple it is.
You keep me learning new stuff thanks to your excellent videos. Thank you !
Innovonics used this method in their broadcast industry tuners such as their 530 modulation monitor. They take the broadcast band down to the very common 10.7 MHz first IF. Then they drop that by 10MHz leaving a 700 kHz 2nd IF, ideal for the broadcast band. A fully loaded broadcast station with stereo and RDS at 100% modulation, +/- 75kHz in North America, is 253kHz occupied bandwidth. 700k is a pretty good number. Well implemented this method has extraordinary fidelity.
And they did this with familiar components of the day, CD4053, 4046, 74HC148, the venerable SA602 and basic transistors 3904, 3906. PLL tuner control was by the popular MC145170. They have the circuit description and schematic for the 530 and 531 on their website. As broadcast gear these were intended to be field serviceable.
Very informative video. Helped me visualize demodulation and how exactly it is done.
Remarkable video. Thanks Alan!
Outstanding as always. Clear, concise explanations and interesting content.
Great video. Thumbs up.
This actually could be a pulse counting FM demodulator if the pulses were fed into digital circuitry which calculated the time between successive pulses (i.e. the instantaneous period of the output) and the reciprocal of this would then be the instantaneous frequency which represents a voltage at that point in time.
Great explanation and video as always Alan. Thanks for the shout-out to my old receiver project too!
It's the least I could do for a fellow engineer, amateur radio operator, and most important - another Alan that spells Alan correctly!
@@w2aew us Alan's must stick together!
Love your videos. Very straight forward and clearly explained!
A real experts pointer. Tek.
That was very interesting. Never knew there were multiple ways to discriminate FM. Cool stuff!
I used to demodulate FM with quadrature fm demod or pll circuit ,by reading the output dc voltages ,THANK YOU aLOT
I realy love your way explaining things. Thank you for spending time on it.
Dick Netherlands.
Your notes are great!just don't forget to take a break sometimes, tech, computers, etc is more addicting to me than ANYTHING!!!!!!
Brilliant, I'm alway looking for different ways to come do things .
As always educational and entertaining. Thanks.
I made pulse count FM radio... sounds is good and circuit is simple ( good for beginners ). dont need special measurements and settings ( like a clasic discriminator circuit )
Awesome video, thanks for sharing this technique - I always learn something from each video you make
Fantastic video Alan - as always. I found this at just the right time as I'm playing with fm modulation and demodulation for the first time. I built your circuit and was amazed at how well it worked. I'm looking at building it into a larger receiver like VK2ZAY. Thank you so much for explaining so well. 73 Nick M0NTV
Useful video. I like it
Clear explanation and demo as usual, great stuff, thanks.
Great video.
There is also another reason why we need to down convert to use this demodulation method, and that is it is very difficult to generate sharp pulses with low duty cycle at high frequency.
For example for 100MHz signal, you need to generate pluses with 1ns or better ( Lower pulse width) and then integrate them.
Of course, you can use say 20KHz bandwidth integrator (bandwidth of sound or info) that is not hard, but generating 1ns pulses or better is hard, but not impossible.
Maybe, this is another way of direct conversion receiver.
Thank you for this video sir, really very useful and interesting, thank you for your time and effort.
I have a Kenwood KT-815 receiver, which uses a pulse count detector. Both the specs and the sound are excellent. Belar uses the pulse oount detector in their FM modulation monitors, --de N3TPS
*VERY* interesting - I didn't know of any commercially made receivers that use this type of FM detector - thank you!
@@w2aew The kT-815 is dual conversion, it has a normal 10.7 MHz IF strip for selectivity, after which the signal is heterodyned to around 200 KHz for the detector. They get 0.04% THD and 80 dB S/N (full quieting) is stereo mode!
@@w2aew Very elaborate and clear presentation, thanks a lot !
I am interested to study and finally make some pulse-counting detectors, so I watched your clip very carefully. Congratulations! While studying the history of this type of demodulation, I discovered that there were many companies that produced FM tuners with pulse-counting. The undisputed champion is Kenwood, but I also noticed Accuphase, Heathkit and Fisher. Here are some FM tuner models equipped with pulse-counting demodulators: Kenwood 600T (1976), KT-615/815/917 and L-07TII (1979), L-01T and KT-80 (1980), KT-9XG, KT-900/1000/1100 (1981).
Kenwood produced pulse-counting discriminators using discrete components, discrete+some known ICs (TA7060P, SN74LS03 or SN74LS38N, HA1457, NJM4558D) and dedicated/proprietary ICs (TR4010A and TR4011).
Another FM tuners with pulse-counting: Fisher TFM-1000, Heathkit AJ-1510AS .
I hope that these informations will help.
Also, a good source of info is the "Tuner Information Center" at www.fmtunerinfo.com/kenwood.html .
Good luck and be sure you have one more student watching your clips! :)
Best 73s de Cezar YO3FHM
I always thought the carrier frequency was fixed, and it was another signal that frequency modulated.. now I know better! Thanks!
Good to see a new vid - excellent as always.
Very interesting Alan! Always enjoy your videos. I am also working on FM receivers (see my channel), but did not know this method of FM demodulation yet. I’ll certainly give it a try. My preferred method at this moment is using a crystal filter and tune the IF to be on the slope of the filter.
Yes, slope detection works and relatively easy to implement, but it can be non-linear which can add distortion to the detected baseband signal. I'm sure you've likely found this.
Nice MDO and nice demo!
Enjoyable video, thanks for sharing, it gave me a lot of information that i didn't know. Thanks
Ah the nostalgia. I first came across the pulse counter in point to point microwave links for video and audio distribution. One thing I can't drag out of my memory is that we were told the pulse counter was inherently 3dB less noise than a Foster Seeley, but I am damned if I can remember why.
Very clearly and well explained.
Great stuff! This is a new one for me. Great job as always. Thanks a lot.
Oh man, that is good stuff. FM demodulation has always sort of mystified me and that goes a long way towards making the picture clearer. I'm definitely going to take a stab at building one of these and testing this out!
This is a bit of an obscure technique for FM demod, but it works. Most probably use a pll.
@@w2aew - yep, I just ordered a bunch of 4046 chips a week or so ago for doing some FM demodulation experiments. But I think my mistake before was in thinking that there was exactly one (and only) way to do FM demodulation (using a PLL).
Now that I can see that there are different ways, the whole idea just makes more sense.
It's kinda hard to explain, but in any case, thanks for the video. It's a big help (as is all of your content!).
A very classy pointer !
You are a magician! Love your videos!
This is actually the first time I see RM being used for practical (rather than sound design) signal processing... My background is basically not electronic so I still need to learn a lot. Giving that this is already the 303rd video I guess I have a lot to catch up then :)
Thank you for an interesting video. The IF filter cannot remove the image. There are always two tuning points. I have used this technique for 2m FM reception. Also there was a tiny pocket FM receiver made by Sinclair in the UK in about 1970.
I've been thinking of something similar, if I could use the FM modulated rf to change and alter the freqency of a square wave oscillator, then simply by integratigration of the edges (via a small capacitor and r ) [I'm a great fan of Shmit triggers , namely using a coil instead of a r in the feedback! ] obtain pulses praprtional to the modulation frequency. Using say the +'ve pulses and then average out to obtain the Af !
Yep, another way to skin the cat...
Very good explanation, very interessting, thank you for the video
Thanks! was so much interesting. Please take care of yourself and upload more often 😁👍🏻
Great content, as usual. What tablet/software are you using? it looks very nice and readable.
It is from Remarkable (www.remarkable.com). Pricey, but works very well.
Loved he signal source material at the end! :)
Would love to see more radio circuits analyzed by yourself .. Thanks Again....
Many thanks for educating me. Slowly working my way from a simple regen receiver towards a proper heterodyned FM receiver. Question- Why do many of the FM or multi-band receivers have their VC connected to the positive rail instead of ground? Specifically the TA2111 chip... but I've seen several others with this set up. Do they swap the polarity for convenience sake?
That ”Remarkable” tablet looks amazing. Love that you can have graph paper as a background. Can it do smith charts too?
Not natively, I'd have to see if I can upload a background image...
Thank you, excellent video
Awesome video. Very well explained
Awesome video .. I have to ask though, what tablet is that?
It is from Remarkable (www.remarkable.com). Pricey, but works very well.
@@w2aew thanks a lot !
fantastic! thanks!
Good job dude 🙏🙏🙏
Excellent!
Thank you
Thought about using a digital function like a Schmidt trigger for the limiter function? Really like all your postings.
I always enjoy your videos, but I have to ask. Are you secretly Forrest Mimms III? Whenever I see you draw everything out on the graph paper it brings me right back to the little paperbacks from radioshack.
The Mimms Engineering Notebook series from the 70s-80s were a big influence on me as a kid.
Lots of good info. Thanks.
Question: Would this set up require tracking between the RF and LO or could the LO be a separate circuit without the use of a ganged capacitor? Ideally, I guess it would. But I'm wondering how difficult it will be to maintain such a small difference in frequencies when tuning through the band... If the LO was fixed at 97MHz would that result in a single station only receiver?
No tracking needed if you don't use any type of tracking preselector. Simply adjust the LO to put the station of interest into the IF.
@@w2aew
So the antenna coil does not form a tuned circuit? Just amplify the rf and feed it to the mixer along with the LO. The LO would be inductively coupled to the antenna coil and tuned... yes?
Great video.
Finally a fm demod i can actually build
The bloody thumb is to freaking small! Thanks Alan! ✊👍👍👍👍👍
Can you make a video about how to wind flyback transformer.I have watched your #209: Basics of Phase Dots on Transformer Windings.And it was a great lecture.I am looking forward for your videos.
thank you!