LIQUID LEVEL MEASURING APPARATUS

PURPOSE:To separate the signal due to the vibration of a wave from the signal of a liquid level to which the vibration of the wave is added, by synthesizing the integral characteristic between the change quantity of a liquid level and the liquid level and a secondary vibration characteristic representing the vibration characteristic of a wave front to simulate the movement of a liquid surface. CONSTITUTION:The difference between the inflow quantity f1 and outflow quantity F0 of a tank is divided by the cross-sectional area A of the tank in a divider 13 and the divided quantity (u) is integrated by an integrator 14 to calculate a liquid level (r) but the liquid level theta actually detected by a liquid level meter becomes a value receiving the effect of the vibration characteristic 15 of a liquid surface. Then, the vibration characteristic of the liquid surface is made approximate by a secondary vibration characteristic, and the integral effect of the integrator 14 and the approximate characteristic are realized in the forms of signal processors 17, 18 and the quantity (u) calculated from the inflow quantity F1 and the outflow quantity F0 by a signal processor 16 is inputted thereto to simulate the movement of the liquid surface. At this time, the difference (e) between an actual signal theta and the quantity appearing corresponding to the signal theta in the signal processor 18 is fed back through proper gains 19-21 to reduce an error.