AM Stereo pilot signal detection circuitry
US4503397A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 17, 1982 |
| Grant date | Mar 5, 1985 |
| Priority date | — |
| Expiry date | Jun 17, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04H20/49
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A stereo pilot signal detector for an AM stereo receiver connects an input signal to a train of pulses corresponding to zero crossings of the input signal. These pulse lock a shift register having a data input connected with a timer which is reset from the pulses after the shift register is clocked. The timer produces a logic "1" input to the register during a time interval extending on either side of the zero crossings of the stereo pilot signal. If four consecutive zero crossings occur within the window, the stereo decoder and an indicator are enabled. Thereafter, if three out of four zero crossings occur outside said interval, the stereo decoder and indicator are disabled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.