PERSISTENT NOISE REMOVING DEVICE AND CONTROL/MONITORING SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a persistent noise removing device performing more efficient noise countermeasures against persistent noise overlapping on a state quantity measurement signal.

SOLUTION: The persistent noise removing device 33 for use in a liquid level control system 31 removes the persistent noise overlapping on the liquid level measurement signal from the liquid level measurement signal S1 outputted from a differential pressure gauge 11 measuring the liquid level of liquid 4 stored in a liquid storage tank 3. The persistent noise removing device then includes: a PLL 35 generating a signal having a frequency and a phase the same as the noise overlapping on the liquid level measurement signal, as a noise waveform signal; a level detector 36 detecting an amplitude about the noise; a multiplier 37 generating a noise removing signal by multiplying the noise waveform signal by the noise amplitude; and a subtractor 38 generating a noise processed signal by subtracting the noise removing signal from the liquid level measurement signal.

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