| 摘要 |
PURPOSE:To prevent the misdetection in case the noise, etc. of a high level is supplied, by comparing the output of rectification of the filter input with a prescribed level through a comparator and inhibiting the output given from the comparator of the rectification output of the filter with the output of the above- mentioned comparison. CONSTITUTION:The multifrequency signal supplied from an input terminal 1 is fed to the filter 2-1 and 2-2, and each frequency of the multifrequency signal is extracted by the filters 2-1 and 2-2. The output of each extracted frequency is rectified by the rectifiers 4-1 and 4-2 respectively, and the output of rectification is supplied to the comparators 5-1 and 5-2 to produce an output when the input is higher than a certain level. This output is fed to the inhibiting gate circuits 6-1 and 6-2. At the same time, the signal supplied from the terminal 1 is suppressed and rectified by an attenuator 3 to be applied to a comparator 5-3. The signal is then applied to the circuits 6-1 and 6-2 when it is higher than a certain level to inhibit the output of the rectifiers 4-1 and 4-2. Thus the misdetection is prevented when the noise, etc. of a high level is continuously supplied. |
