Patent ID: 7839183
Filing Date: 2010-11-23
Classification: H03K

Abstract:
1. A circuit for regulating sensitivity an output of a squelch circuit, comprising: a clear command signal generating unit to output a clear command signal periodically; an output discriminating circuit having a first flip-flop circuit outputting an first output, a second flip-flop circuit outputting an second output and a discriminating unit, the first flip-flop circuit to receive a signal based on the output of the squelch circuit and to output a first output, the first output being set to a initial level by the clear command signal and being changed to an inverse level of the initial level in one case of when the output of the squelch circuit is in a ‘High’ level and when the output of the squelch circuit rises to the ‘High’ level from a ‘Low’ level after the clear command signal is canceled, a second flip-flop circuit to receive a signal based on the output of the squelch circuit and to output a second output, the second output being set to a initial level by the clear command signal and being changed to an inverse level of the initial level when the output the squelch circuit is lowered to a ‘Low’ level from the ‘High’ level after the clear command signal is canceled, and the discriminating unit being configured to identify that an output state of the squelch circuit is at a ‘Noisy’ state based on the levels of the first output of the first flip-flop circuit and the second output of the second flip-flop circuit after the cancellation of the clear command signal; and a sensitivity regulating unit configured to output a sensitivity regulating signal to regulate the sensitivity of the squelch circuit when the output discriminating circuit identifies that the output of the squelch circuit is at the ‘Noisy’ state, wherein the clear command signal generating unit is provided with a counter to count a predetermined number repeatedly, the counter outputting the clear command signal each time the counted value reaches the predetermined number.