Muting circuit
AssigneeVictor Company of Japan, Ltd.
InventorYasuo Itoh
Life of this patent
Estimating the term…
Abstract
A muting circuit comprises, substantially, a gate circuit for passing or not passing input signals and a circuit for forming a control signal for controlling the gating operation of the gate circuit. The control signal forming circuit has a circuit for detecting the level of a carrier wave in the input signal. A first time constant circuit has a very small time constant .tau..sub.1. A second time constant circuit exhibits a delay time constant of .tau..sub.2 (where .tau..sub.2 >>.tau..sub.1) when a carrier wave component exists in the input and a delay time constant which becomes substantially zero when a carrier wave component does not exist. A third time constant circuit of a time constant .tau..sub.3 (where .tau..sub.3 >.tau..sub.2) is with a 180.degree. phase relationship relative to the second time constant circuit.
Claims15
A muting circuit comprising a cascade of circuits including at least:
- input terminal means;
- means for detecting the level of a carrier wave component in an input signal appearing at said input terminal means;
- first time constant means having a first time constant characteristic for producing an output thereform with a first predetermined time constant in response to the detection of a predetermined signal strength level in the output of said level detecting means;
- second time constant means having a second time constant characteristic for producing an output thereof with a second time constant in response to the output of said first time constant means when a carrier wave component is detected at the input terminal means, the duration of said second time constant being longer than the duration of said first time constant, means for making said second time constant substantially zero when a carrier wave component is not detected by said level detecting means;
- third time constant means having a third time constant characteristic for producing an output therefrom with a third time constant in response to the output supplied from said second time constant means, the duration of said third time constant being longer than the duration of the second time constant;
- and means including a gate circuit coupled to said input terminal means and operating in response to the output signal supplied from said third time constant means to pass or block the input signal, said third time constant means holding said gate circuit in a conductive state to pass the signal during the period of time corresponding to the difference between the third and second time constants.
A muting circuit comprising a plurality of circuit connected in cascade, said cascade comprising at least the following:
- means for detecting the level of a carrier wave component in an input signal;
- a first time constant circuit means responsive to said detecting means for producing an output in a waveform having a rising and falling time constant .tau..sub.1 ;
- a second time constant circuit means responsive to said first time constant circuit means for producing an output in a waveform rising with a time constant .tau..sub.2 which is longer than the time constant .tau..sub.1 and falling with a time constant which is shorter than constant .tau..sub.1 ;
- a third time constant circuit means responsive to said second time constant circuit means for producing an output in a waveform which falls after a predetermined delay time, corresponding to the time constant .tau..sub.2, following the start of the rise of the output of the second time constant circuit means, the output wave of the third time constant circuit means rising with a time constant .tau..sub.3 which is longer than the time constant .tau..sub.2 following the falling of the output of the second time constant circuit means;
- and
- gate circuit means connected to receive the input signal and to be controlled responsive to the output of the third time constant circuit means,
- said gate circuit means passing the input signal responsive to the falling edge of the output waveform of the third time constant circuit means, and preventing the passing of the input signal with a delay of a time corresponding to the time constant .tau..sub.3, said gate being placed in said non-passing condition responsive to the rising edge of the output of the third time constant circuit means.
Dependencies are inferred from the claim text.