| 摘要 |
PROBLEM TO BE SOLVED: To provide a tone detecting device which does not require any filter for obtaining tone patterns, can be used generally, and can divide intermittent sounds into several kinds of signals. SOLUTION: A tone detecting device is composed of an A/D converter 1 which is connected to a main wire and a PBX extension and converts analog signals into digital signals and a signal processing section 2 which processes the converted digital signals as input signals. When a tone signal (dial tone, ring back tone, or busy tone) is outputted from the main line and PBX extension, the signal processing section 2 calculates the power from the inputted A/D-converted digital signals, decides the 'ON' and 'OFF' of the tone signal, and identifies and detects the tone signal from the counted and measured results of the time interval of the signal.
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