Figure 1:

Undesirable phenomena as seen in experiments performed in (a) Fuchs (1967) and (b) Vince (1948) . In both cases, fairly accurate tracking is seen in relatively low-frequency reference signals (i.e., ω < ω_c), whereas undesirable phenomena such as skipped cycles (blue circles), overshoot (orange circle), and undershoot (red circles) are seen in high-frequency signals for ω > ω_c for some ω_c.