| 摘要 |
PURPOSE:To measure a crest value with high accuracy by calculating the maximum measured crest value in the display period of a signal to be measured from the display crest value of a reference signal based upon image data, the ratio of the maximum crest value of the signal to be measured, and the reference value of the reference signal. CONSTITUTION:An audio intermediate-frequency signal inputted to an input terminal 1 for the signal to be measured is inputted to a reference signal inserting circuit 2. A signal in the measurement period which is outputted by the circuit 2 and a 3rd gate signal are inputted to the vertical input terminal IN and external trigger terminal EXT of an oscilloscope 3 respectively. The display image on this oscilloscope 3 is picked up by an image pickup device 4, so image data on the display screen is outputted from the device 4 to an image processing part 6. Then when image data of one image plane is inputted to a processing part 6, the processing part 6 calculates the number A of picture elements of the crest value of the reference value and the number B of picture elements of the maximum crest value in the display period, and outputs them to a data processing part 7. Further, the processing part 7 calculates the maximum measured crest value in the display period according to the numbers A and B of picture elements and the reference value of the reference signal.
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