Sampling with detector and rise time effect. also freq change

Hello,

I'm trying to understand how to simulate sampling with detector which has rise time 25psec.

(up to 15GHz sampling rate)

My signal is a pulse which has periodic change in center freq - let's say dni.

The detector is connected to the scope. My final goal is to simulate what the scope will measure with diffrent bandwidth. (to understand what scope we should get)

Would appriciate your help.

Thanks.