| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for detecting frequency with few arithmatic processing whose accuracy is equal to FFT operation with long number of sample points. SOLUTION: A frequency band A including the signal frequency is detected by the FFT operation with short number of sample points. Candidates for the signal frequency in the frequency band A are, then, selected, based on a mapped spectrum, by performing decimation for columns of sample data and the FFT operation with the short number of sample points. True signal frequency is, then, selected from the candidates, based on a direction of a shift of the mapped spectrum, by shifting the signal frequency by thinning the columns of the sample data and again performing the FFT operation with the short number of sample points.
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