8-8 discusses the stability analysis of closed-loop systems using the
Nyquist stability criterion, and Section 8-9 treats the relative stability analysis of closed-
loop systems Measures of relative stability such as phase margin and gain margin are
introduced here. The correlation between the transient response and frequency re-
sponse is also discussed. Section 8-10 presents a method for obtaining the closed-loop
frequency response from the open-loop frequency response by use of the M and N cir-
cles. Use of the Nichols chart is also discussed for obtaining the closed-loop frequency
response. Finally, Section 8-11 deals with the determination of the transfer function
based on an experimental Bode diagram.