| 摘要 |
PURPOSE:To realize the howling detector with small hardware scale, low cost and high detection accuracy by calculating a short period average of an absolute value of the output of a differential arithmetic means and comparing it with a predetermined threshold so as to detect howling. CONSTITUTION:A binary means 2 converts an input signal 1 into a zero cross signal, a multiplier means 4 and a 1st delay means 3 obtain a zero cross point and a zero cross period detection means 5 detects the zero cross period. Then a time change in the zero cross period is calculated by a differential means 7 and an average value calculation means 8 calculates its short period mean value. That is, it is utilized that an output of the average value calculation means is very small in the case of a signal of a prescribed period such as howling to allow a howling detection means detects howling. Thus, the detector is realized with less calculation quantity and a simple hardware. |
