AM and FM Modulation for Ham Radio Beginners

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[MentalWhiplash]

Even if it's something that I understand completely it's cathartic to sit back and watch Ape explain it...after 5:00 relaxation

[Siskiyous]

Mr Ape, you are a treasure to the ham community.

[kendebusk]

Nice explanation. When I first became interested in radio, I asked a friend who was the engineer at a local AM station what a carrier was. "Waves are nature's way of transferring information from one spot to another, and something has to 'carry' that information." I never forgot that since it makes a lot of sense. If you're making a series of these, I would be interested in seeing (with the scope and analyzer) SSB, RTTY, etc. I have a fairly good idea of how some of these types of signals work, but a picture is usually worth a thousand words.

73 de KA8VLW, Ken in Michigan

[Swamp-Fox]

Nice explanation & demo of modulation. It really helps to be able to see the waveforms and spectrum! Nice scope & sig gen!

[MikeNMAK]

School buses are killing ham radio, LOL. Thanks for another good one, Ape.

[gaptastic]

Thanks for the tutorial, Professor Ape!

[WECB]

Grandma once told me FM/AM stood for "Fine Music" and "Awful Music". I think she was not far off. 😂

For the under 40 crowd, actually AM can sound as good as mono FM. Back in the day, AM broadcasters took great pride in their audio and were allowed to transmit up to 20KHz. Today, the FCC restricts them to 10KHz and most actually only broadcast out to 6KHz! THIS combined with really bad radios is most of the reason why AM got the shaft and now sounds muddy. The physics hasn't changed, just the law and the terrible engineering in our receivers. 73

[richiec]

Since am radio waves travel further at night, I guess that’s why most commercial am radio stations reduce power at sunset and increase power at sunrise. I live in West Palm Beach, Fl and listen to a Miami am sports radio station. During the day it is crystal clear but I can barely receive it at night because they decrease the power output.

[byronshepherd]

I'm know I'm a year late tot he party, but hopefully not too dumb a question: When you displayed the FM modulation deviation, it looks as though the waveform close to the axis is sharper (less deviant) than the waveforms moving outward... why aren't they the same? If the offset/deviation/whatever, is set for 900khz, why isn't it uniform? Is it just representative of "wavespread" with distance or something?

[thebnbaldwin]

Good little primer video. I worked on AM transceivers for years, FM was hard for me to wrap my head around at first. I'm so used to looking at signals on a communications service monitor that the scope, not so much the SA looks strange to me. The SA is a familiar view after tuning duplexers and intermod hunting. Thanks Ape! de WB3BIT

[tkflanagan]

YOU are an AWESOME instructor and if I don't get something.... I can play it again!! THANK YOU🦇

[ritamsarkar]

Please please reply! An audio signal can have varying frequency and amplitude and both are the part of the information. But as per my knowledge, Frequency modulation is a technique where the frequency of the carrier wave is varied according to the amplitude or intensity of the modulating signal. So how does this work if under FM, if the carrier wave only has the in information about the intensity or the amplitude of the modulating signal as in FM, the carrier frequency is varied according to the intensity?

Someone had told me to use a Voltage Controllable Oscillator(VCO), but the question remain as VCOs also vary the frequency according to the intensity of the input signal.What if the input signal is also varying in frequency (ofcourse inside a range)?

[pcrequest]

I think a lot of the differences discussed here are not due to inherent differences in mode as mentioned, but rather differences in bands, and bandwidth used. For example, FM commercial radio signals don't travel as far because it is a very different band than AM commercial radio. Not because it is FM.

[LeeMcc_KIYPR]

Good work.

Which instruments did you use? Scope, SA, and generator?

[SymoTube]

Another good video! I’m in the market for an o-scope, which Rigol is that? I saw 8GSa/sec at one point. Is that an MSO5204/5354 or a DS7000 series? Thanks!!

[traderlarry]

Where did you get the ruler contact paper for your worktop?

[HamRadioPrep]

Love the video Mr. Ape! We would love to partner with you at some point!

[jessejames]

I was really hoping to learn about how the two modulations are created/ different by how they modulate. What I think I know is attenuation modulation AM is driven by the amplitude of the modulation vs frequency modulation is well the actual frequency of the wave or voltage. Is that even remotely close?

[ting]

I don't quite understand AM. For FM, it make sense that you will create "bandwidth" because your frequency is deviate from the carrier. For example, if you modulate 1kHz to 20MHz carrier. It makes sense to have 20MHz, 20.1MHz, and 19.9MHz peaks on the spectrum analyzer. However, how come an AM modulation can create bandwidth???And how can you Amplitude modulate 1kHz to 20MHz amplitudely??? Thanks.

[oldolfmann]

So glad I did not learn from this guy, too much wrong terminology used and misinformation here.