1. If a Bode plot has a constant magnitude of 1 (or 0db), where do I read off the phase margin? Is it when it starts going down from 1?
I guess this is the same question as if the magnitude plot crosses 1 several times, is the phase margin the point of these where the phase is at is lowest? (smallest PM)
2. Also, for Nyquist, If the Nyquist diagram crosses 1 exactly, is the system stable or not?
3. If you need to add a phase of 100 deg, ould you use 2 lags?