supported by the National Natural Science Foundation of China (Nos. 51177035, 50837001, 51177037, 60974022);the Science and Research Development Foundation of Hefei University of Technology (No. GDBJ2010-003)
An adaptive notch filter is presented to estimate the fundamental frequency and measure both harmonics and interharmonics of an almost periodic signal with unknown time-variant fundamental frequency, which has the ro-...