On the performance of a single loop OEO using dynamic control BPF in the face of noisy angle modulation

Dynamically controlling the resonance frequency of a tuned circuit by the modulating signal extracted from the synchronizing FM input is a wonderful technique. It not only increases the linear region but also reduces the output THD by judicious control of the feedback gain. This communication presents the study of lock range of OEO using dynamic control BPF under the influence of noisy angle modulated signal. The instantaneous amplitude and phase governing equation of the OEO in presence of noisy FM signal has been derived. We show the dependence of the noise variance on the input carrier-noise ratio. It has been observed that higher values of input carrier-noise ratio and lower values of the noise variance gives large values of lock range for a given value of the input carrier-noise ratio. The improvement in performance of the OEO using dynamic control BPF over static BPF have been presented. The steady state condition existing in the OEO using an approximate and exact analysis is given.