| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that conventional frequency information detection devices require circuits such as differentiator circuits, phase-shift circuits, and integrator circuits, as well as complex computation to detect frequencies.SOLUTION: A cosine value estimator 21 estimates a cosine value [cos(ω[t]+θ')], which is a differentiated instantaneous value V[t] of an input signal Vat time [t] required when computing frequency information, using an instantaneous value V[t-1] of the input signal Vat time [t-1], an instantaneous value V[t+1] of the input signal Vat time [t+1], and a known value. Then, a phase estimator 22, phase variation calculator 31, and a frequency estimator 32 compute a phase α[t], a phase variation Δα[t], and estimated frequency information of the input signal V, respectively. A moving average calculator 40 then computes a moving average value (of the estimated frequency information). Arithmetic expressions are thus simplified, which reduces computation load.SELECTED DRAWING: Figure 2 |
