Total posts : 45366
Yes, this particular spectrum instrument has two bandwidth settings: 20kHz and 400kHz.
Of course the 20kHz is suited for AM signal obervation, and the signal peaks show no side-to-side swing at all, only up and down.
If I switch to 400kHz on the medium wave band it’s like zooming in too close to the picture and seeing about 20 stations in one glob.
Looking at an FM station with 400kHz bandwidth the signals shake back and forth like poplar trees in an earthquake.
On FM I can see the HD signals side-to-side of the carriers that have them, and they look like tall shrubs being shaked vigorously to loosen the fruit.
So what you’re saying is, shaking your head “yes” is frequency modulation, and shaking your head “no” is amplitude modulation(?)