AM Stereo receiver logic
US4379208A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1980 |
| Grant date | Apr 5, 1983 |
| Priority date | — |
| Expiry date | Nov 13, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04H20/49
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In an AM stereo radio receiver, a pilot signal is recovered from the phase modulated channel. The pilot signal is sensed by means of a bandpass filter tuned to the subaudible signal frequency and is used to operate a detector-switching amplifier combination. The switching amplifier actuates a visual indicator which shows the presence of a stereo broadcast. The receiver is provided with an electronic blend function that operates in response to the pilot signal and an excess phase signal that is present when the receiver is mistuned. OR Logic, which responds to either mistuning or a lack of stereo pilot signal, switches the receiver to monaural response. If desired, further OR Logic can include response to weak signals, in which case an improvement in signal to noise ratio is achieved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.