"If your scope is simply displaying the individual samples, and drawing straight lines between the points, then you probably need a sampling rate of at least 20x the carrier frequency (or more) in order to avoid having the display confused by the "chopping off" of the tops of the waveforms when the sampling time doesn't happen to fall right on the peak of the waveform. 50x is even better. "

Sure, but where is the button for that ?