FREQUENCY MODULATION - PART I - BASIC PRINCIPLES - Department of Defense 1964 - PIN 28398 - FUNDAMENTALS OF AM AND FM RADIO COMMUNICATION, HOW FM ELIMINATES PROBLEM OF ELECTRICAL INTERFERENCE, FUNCTIONING OF FM RADIO EXAMINED IN DETAIL.
I have been taking an electronics communications class and i am quite surprised at how quick and easy this video describes material that my book and professor took weeks to convey. Pure awesomeness!
Ya I have to admit there are auditory learners, visual learners, and mechanical learners. When information is presented to me in cheesy silly animated diagrams and the like almost exactly in this video's format, my brain just gobbles it up like a steel trap.
Well, in 2022, there is incentive to monetize and keep peoples attention making actual information is increasingly more difficult to find.. The whole population wants to monetize a YT channel. How are channels profitable..?
I've understood AM radio for 20 years and have never been able to get a handle on FM regardless of how much I read about it. It's crazy such an old film would make it so simple and so clear. Sadly it makes me wonder why America has lost it's place as a technical leader. In the '40s we were so far more advanced than 99% of the other countries. Today I'm guessing we are in the 50th percentile.
I am an operations manager at a Christian radio station and these things had always been so confusing, even after watching so many vidoes. This is so helpful in clarifying every one of my questions! I'm going to watch it through a few more times to really sink it home. Thank you for posting this as it will literally change my life and will change my coworkers as well who interact with these principles! Thank you Thank you Thank you!
@jfdonnald If you're talking about the part where the audio wave is rotated vertically, it's just showing the direct effect of changes in amplitude in the input audio wave to changes in frequency in the carrier wave. Remember, the carrier's frequency is represented by the black horizontal line, and movement along that line only changes the frequency.
@msingletary1984 something called a piezoelectric material is used. this creates electricity when it is compressed or released. when hooked up to a microphone so that sound is turned into mechanical movement these properties can be used to make an electrical signal. no electricity source is needed, however a source is need to power the occilator as you have probably noticed that it has no actual input.
@@jakepalmiero4293 1Hz = 1cycle/s, that is true.. but it's funny to me how probably back then Hz wasn't a very established standard, so they would just invert it and talk in cycles. Nobody talks in cycles anymore hehe
I see people talking about how this video and those like it clear up detail and information about these topics better than their teachers. I don’t see it at all, these videos miss details that are impossible to infer. Like from this one video alone, try and build an fm transmitter and receiver, you couldn’t do it because they don’t show actual circuits with valued components, it’s all just building blocks. How exactly do you make an oscillator that you feed an audio signal into for it to change its resonant frequency, it’s just not there.
I could be wrong but I would say that the microphone doesn't create the electrical signal. Power must be sent to the microphone for the microphone to create distrubances in (this is the signal).
Little did people know that FM synthesis would become a thing and would be responsible for the Yamaha DX7 and the Yamaha 2612 soundchip in the Sega Genesis.
14:35 he mixes up frequency whit amplitude.the frequency deviation is at 100% at its maximum,not the amplitude.this is frequecy modulation after all.unless im missing something.
I know that am commenting to an old comment. Initially I also had the same point as yours, but later understood the point he makes in the video is correct. Amplitude variations manifests as change in frequency therefore high +ve amplitude results in high frequency and -ve amplitude results in low frequency, this can be understood at 07:40.
They didn't call frequency units Hertz, because Hertz was a German physicists. :P Instead they called them cycles. This was recorded in 1964 and SI was established in 1960.
Thank you, but I guess you're a bit wrong also. Hertz is actually cycles per seconds, so my first question is somehow stupid. And Hertz was SI standart from 1960 - 4 years before this was publicated.
Tim Deignan not actually true. Galaxies that are moving towards ours are said to be “blue shifted” and galaxies moving away are “red shifted”. It is negligible for these purposes, but to say it only applies to sound is actually incorrect.
in an FM signal you have a limiter to limit the amplitude so how does the demodulator work once the limiter limits the signal to certain amplitude???? why cant all those tutorials be explained like this i wonder
Not true. The Doppler effect also occurs with radio. The effect is less but still very real, and can be a problem for satellites which orbit very quickly.
its a good movie, but i dissagre when he talks about the rest frequency and the deviation in FM. The deviation is not about the amplitude of the signal, but the frequency
Rafael Sartori I know your comment is old, but this video has fascinated me and I’d like to attempt to explain my perspective for anyone else stumbling upon this. The deviation is about both amplitude AND frequency. Remember, one cycle (or Hertz) will cause the frequency to go both above and below the rest frequency. How far it goes above and below rest frequency (modulation) is what affects the amplitude of the sound wave. The illustrations towards the end of the video are confusing because they are showing the amplitude of the wave changing with respect to the rest frequency, even though we can not. visualize the frequency of the input wave (RF) changing.
I know that am commenting to an old comment. Initially I also had the same point as yours, but later understood the point he makes in the video is correct. Amplitude variations manifests as change in frequency therefore high +ve amplitude results in high frequency and -ve amplitude results in low frequency, this can be understood at 07:40
