Muting circuit for an FM radio receiver
US4398060A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 6, 1981 |
| Grant date | Aug 9, 1983 |
| Priority date | — |
| Expiry date | Aug 6, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G11/08
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Signal transmitting operation is effected in a muting circuit when a first constant current source connected to the emitters of first and second transistors is operative with a second constant current source connected to the emitters of third and fourth transistors being inoperative. The signal transmitting operation is not effected in the opposite case. A bias resistor is interposed between the bases of the first and third transistors. To eliminate the popping noise when the power source is turned on, a switching element is connected parallel to the bias resistor and is kept in the ON state for a predetermined period of time after making of the power source. In an FM radio receiver, the output signal of a detuning detection circuit is applied to the input terminals of first and second mute control circuits, and the muting operation of a pre-amplifier for amplifying a stereo composite signal is controlling by the first mute control circuit while the muting operation of a muting circuit connected to the output of a stereo demodulation circuit is controlled by the second mute control circuit. Discrimination levels of these first and second mute control circuits are set to mutually di…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.