See if the DSO has Phase Wrap or Unwrap feature.
Best
Hello.
I have an MSO5074.
And when using BODE PLOT, a small green square appears on the PHASE line, which is the GM(0º).
In the case of the photo, it gives GM(0º): -17.86dB | 1.002kHz.
The question is: what is it for and how to use this GM(0º)?
All the best.
BRZ.tech
My guess is Gain Margin (GM), the brother to Phase Margin(PM). GM(0º) of -17.86dB | 1.002kHz probably means the gain curve is 17.86dB above unity gain (0dB) when phase plot crosses 0 deg at 1.002kHz, you can see if that's true in your plots.
No idea what your circuit under test looks like, but for loop response of a closed loop system, like a power supply, phase margin (PM) above 45 deg (some may argue you should have above 50-60 deg) , GM below -15dB (ideally -20dB), gain plot crossing 0dB line at roughly -20dB/decade means you have a stable system.
Edit: I realise you were referring to the photo a few posts above, looks about right. Though the GM measurement don't really tell you anything in this situation.
Edit Edit: Actually I suspect the scope is confused by the phase wrapping and thinks the point when the phase curve "crosses" 0 deg is the GM frequency, when in fact there's not a real crossing occuring at 1kHz, but just an artifact of how the phase plot was plotted. Slightly misleading in my opinion.