| 摘要 |
A Kármán vortex flowmeter is disclosed which comprises, in addition to a conventional vortex frequency detector means for outputting an electical signal including a vortex frequency signal component, a filter group consisting of a plurality of filters having a gradation of pass bands covering the variation range of the vortex frequency, and a waveform sharper circuit coupled to the output of the filter group for forming a pulse-shaped signal having a frequency equal to the vortex frequency. A filter in the filter group is selectively coupled to the shaper circuit in response to the output frequency thereof. The shaper circuit, on the other hand, holds the peak and the bottom level of the electrical signal; compares them with the positively and the negatively shifted electrical signal, respectively; and sets and resets a flip-flop when the peak and the bottom level cross with the positively and the negatively shifted electrical signal, respectively, the peak and the bottom level being reset after each occurence of the crossing. The flip-flop outputs a pulse-shaped signal having the vortex frequency even if the electrical signal contains high and low frequency noise components.
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