| 摘要 |
An instrument for measuring a gap between it and an imposing surface comprising a gas conduit having an inlet and an outlet, a sensing orifice, a gas pump connected to the inlet for applying an alternating pressure to the gas conduit so that the puffs of gas are directed from and back to the sensing orifice. The timing frequency rate is determined by the adding of a new dimension to the well-known Helmholtz resonance frequency parameters when used as feedback to an amplifying-oscillator circuit. This frequency pitch rather than its amplitude is now used to determine the gap distance, and this frequency can be perfectly transmitted to eternal observers. This frequency pitch can be counted over longer periods of time to improve its sensitivity and minimize system noise.
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