| 摘要 |
PROBLEM TO BE SOLVED: To attain the flexible setting change of tone signal detecting characteristics with a little memory consumption by shifting the frequencies of a signal to be detected only by set frequency shift amounts, comparing a signal level outputted from a band pass filter with a prescribed threshold, and detecting the signal to be detected as a prescribed tone signal when the signal level is higher than the threshold. SOLUTION: In the constitution of a tone detecting part 10a, a filter coefficient group corresponding to destination is omitted in a filter coefficient storage part 21, and a specific value is set in each filter coefficient K1-K6 of a band pass filter 20. An input signal to be detected is inputted through a frequency converter 25 to a band pas filter 20a. The oscillation output of an oscillator 26 for oscillating with frequencies set by a frequency storage part 27 is inputted to the frequency converter 25, and the input signal is shifted by the oscillation frequencies of the oscillator 26, and inputted to the band pass filter 20. The frequencies are set in the frequency storage part 27 by a system control part.
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