Given this limitation, it would seem impossible to extract a Bode plot, however, consider the well-known relationship between the closed loop and open loop responses of a feedback system.

Bode plots – or frequency response graphs – are found in just about every piece of literature for high-end audio equipment. It’s a simple idea, graphing frequency over amplitude, … ...

The Bode plot is recognized for its simplicity and the simple asymptotic approach makes the method useful for both design and assessment of power system control loops.