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    • 18. 发明授权
    • Method and apparatus for DTMF detection
    • 用于DTMF检测的方法和装置
    • US5818929A
    • 1998-10-06
    • US354939
    • 1994-12-13
    • Tatsuya Yaguchi
    • Tatsuya Yaguchi
    • H04Q1/45H04M1/50
    • H04M1/505
    • The total energy of a signal that has entered from a telephone line is detected before the signal is applied to an AGC circuit. After the signal is applied to the AGC circuit, the energy of a DTMF signal, which comprises one frequency from four high group frequencies and one frequency from four low group frequencies, is detected through a band-elimination filter having a short energy-propagation delay time with respect to pass-band frequencies. By detecting the DTMF signal based upon the detected energies, detection of the DTMF signal can be performed in a short period of time and erroneous detection can be suppressed.
    • 在将信号施加到AGC电路之前,检测从电话线输入的信号的总能量。 在将信号施加到AGC电路之后,通过具有短的能量传播延迟的带除滤波器来检测DTMF信号的能量,其包括来自四个高组频率的一个频率和四个低组频率的一个频率 相对于通带频率的时间。 通过基于检测到的能量检测DTMF信号,可以在短时间内执行DTMF信号的检测,并且可以抑制错误的检测。