| 摘要 |
PROBLEM TO BE SOLVED: To surely remove any periodic noise superimposed on a measuring signal without delaying the measuring signal. SOLUTION: A first noise frequency detecting part 1 FFT-processes a measuring signal, and detects the frequencies of a periodic noise signal as first detected frequencies. A noise signal analyzing part 5 calculates a mutual correlation function between the first detected frequencies and a measuring signal, and calculates the amplitude and phase of the periodic noise signal superimposed on the measuring signal posterior to a point of time when the mutual correlation function is calculated based on the mutual correlation function. A cancel signal preparing part 7 prepares a cancel signal from the first detected frequencies, amplitude, and phase related with the periodic noise signal. A signal cancel part 3 calculates the measuring signal and the cancel signal, and cancels the periodic noise signal.
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