| 摘要 |
PROBLEM TO BE SOLVED: To accurately select waveform data of one period (or a period of magnification of an integer times of 1/2) by using a cursor, by detecting an intersection of a waveform obtained by removing a DC component of an input waveform and a zero level. SOLUTION: An intersection of a waveform obtained by removing a DC component of an input waveform and a zero level is detected. A cursor is moved only on waveform data of this intersection, and an area of one period (or a period of a magnification of an integer of 1/2) of the input waveform is selected. As a means for detecting the intersection, a zero-cross detector 30 for comparing the analog input signal with a zero-cross level voltage by a comparator is provided. That is, an output of an amplifier 2 is connected to an A-D converter 3, and simultaneously also connected to an LPF 31 for constituting the detector 30, an output of the LPF 31 is connected to an input terminal of a zero-cross detector 32, and its output is connected to a memory 4. A digital signal from the converter 3 is stored in the memory 4 as waveform data.
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