| 摘要 |
<p>A measuring apparatus employing a differential transformer includes a high-frequency oscillator (50) which generates a high-frequency signal having a frequency higher than the excitation frequency of the differential transformer, a frequency divider (52) which divides the high-frequency signal to generate a driving signal for the differential transformer, a multiplier or divider (60) which reduces the frequency of the high frequency signal by the frequency of the driving signal, a mixer (66) which mixes the output from the multiplier or the divider with the output from the differential transformer, a high-pass filter (68) or a band-pass filter which cuts a low-frequency component of the output from the mixer, and a double balanced mixer (74) which synchronously detects the output from the high-pass filter or the band-pass filter with the use of the high-frequency signal. With the use of the thus configured apparatus, an output signal having a fast response speed can be obtained through the use of an existing head having a low excitation frequency.
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