Filters
The R&S RTB2000 provides several ways to filter the input signal:
Lowpass filter by selecting a bandwidth limit in the acquisition path (vertical channel settings), see "Vertical Settings".
Create a filtered math waveform (lowpass or highpass). Filtered math waveforms are described below.
Thanks, alsetalokin4017, the Math low/high filter is quite useful to know about!
FYI, The vertical channel filter is just a 20 Mhz setting, that filters nothing in my use case (frequency range: 100 Hz - 3000 Hz).
The Math filter is useful when an exact particular low pass frequency is already known. In my case, I don't know the pass through frequency - I'm using the oscilloscope to explore and find those in the first place! Also that pass through frequency changes all over the fretboard as well - across 3 octaves! It is not feasible to keep going into the low pass dialog and increasing that frequency little by little (say 10 times on average per note) and do that for 50 notes. (500 times total).
What would be great is if the Math filter allowed a filter based on
voltage. For all the different frequencies I'm interested in,
the voltage at that frequency is above a threshold and anthing less than the threshold (ie higher harmonics, not as high in amplitude), I want to ignore. The frequency changes from 100 to 3000 Hz but threshold voltage (for all frequencies) is above 3mV - anything less than 3mV I want to ignore completely in all the metrics/calculations.
This is closely tied to the trigger threshold. I've seen mention of a gate in some scopes where you can simply drag a line and it will only show metrics for above that line. This seems to be a very trivial (and useful) thing for a scope to do - any way to do that in R&S RTB2004?