NOISE RESPONSE AGC CIRCUIT

摘要

PURPOSE:To improve the unnatural point of call, by detecting the level at a low range of noise spectrum and then controlling the gain of calling system. CONSTITUTION:The noise given through the microphone 1 is applied to the band- pass filter 12 to detect the level of a low range in the noise spectrum. Then the noise is supplied to the gain varying circuits 4 and 5 via the rectifying circuit 13 and the comparating circuit 14 to control the gain according to the noise level. It is advised to set the time constant of the circuit 13 with a long rise and fall so as not to be sensitive to a sudden fluctuation of the noise level.