Inter-area oscillations can be identified by analyzing the signals obtained from Phasor Measurement Units (PMUs) dispersed across the power network. In this paper, signals obtained from PMU are decomposed into monocomponent signals by a filter bank based on Zolotarev polynomials. A narrow bandwidth of 0.1 Hz is designed in the range of 0 to 1 Hz using Zolotarev polynomial based filter bank. Modal frequency and damping are estimated from the decomposed monocomponent signals through Eigen Realization Algorithm (ERA). The proposed method is demonstrated on two-area test system and the simulation results are presented. © 2015 IEEE.