I am using 33220A generate a burst of pulse, like attached. it works fine. and if I use a 2K bandpass filter, I got a sine wave. when I use modulation generate a very similar waveform. but I instead of get a 2K sine wave after a 2K bandpass filter, I only got a straight line.
what is the fundamental difference between using a burst of pulse and AM modulation?
thank you very much,