Foundation Online - AM, FM and SSB Visualised

As part of our Foundation Online course, this video uses a Software Defined Radio to take a look at AM, SSB and FM modulation using a spectrum view and a waterfall view. More at www.hamtrain.c...

[@dgrewar]

Thanks Pete... this helped me a lot... thanks

[@VK9TOM]

Good work getting New Ham’s licensed 73 Tom VK3FTOM

[@VK9TOM]

Also very educational

[@nhilenh8403]

the video image is too poor, you need to fix it more

[@scottb8423]

What are the axes on the graphs, for AM, and for FM? (I have the video at full resolution, but can't make out any of the characters). For AM, I think x=frequency, and y=amplitude. But what about for FM? I ask because: the AM demonstration looks like what I expected (the amplitude changes for many different side frequencies)... but FM looks very nearly the same.

[@EssexhamUk]

What you're looking at is a display of a part of the radio spectrum. The red vertical line denotes the frequency that the receiver is tuned to (144.550MHz). Left of this line, the frequency decreases, and to the right, frequency increases. On the top half of the screen, we are seeing received signal strength (in dB). On the bottom half of the screen, we are seeing what's called a "waterfall", which is what the signal looks like over time.

[@Ziplock9000]

@@EssexhamUk He's asking why a carrier that is say 140Mhz when Amplitude Modulated starts spilling into adjacent frequencies when it should only be the amplitude at 140Mhz that changes. This is what you'd expect from FM... that the signal would make the carrier shift into frequencies