| 摘要 |
PURPOSE:To decrease the hardware and amount of operation by using an adaptive filter so as to constitute a signal detection circuit in a tone detector of a sound in-band signal. CONSTITUTION:When an input signal is inputted, the adaptive filter 11 calculates a forecast signal value, calculates an error with an input signal and a deciding circuit 13 decides the range of an error. A control circuit 14 of a root formes the next forecase signal value, controls the adaptive filter 11 so as to operate it for minimum error. Furthermore, when a forecast error is consecutive for a certain range, for a certain time, a discrimination circuit 13 decides what a signal is. On the other hand, an input signal is given to an input power detection circuit 12, which gives an output when the power is a specified power or over and when the signal is consecutive for a specified time or over, the circuit controls that the output of the timer circuit 15 outputs output information to the deciding circuit 13. Thus, the deciding circuit 13 outputs signal information. |
