Stereophonic receiver noise eliminating device
US4306112A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 28, 1979 |
| Grant date | Dec 15, 1981 |
| Priority date | — |
| Expiry date | Aug 28, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/1653
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A circuit for eliminating pulsating electrical noise in a received and detected signal. A phase-locked loop circuit produces an output signal whose frequency and phase are identical to those of the stereophonic demultiplexer pilot signal of the composite detected signal. The output from the phase-locked loop circuit is subtracted from the pilot signal at a point prior to a switching circuit which disconnects the demodulated signal from the input of a stereophonic demultiplexer when noise is present and a level holding circuit maintains demodulated signal at the level it had immediately prior to its interruption. By completely removing the pilot signal from the composite signal prior to switching without otherwise varying the phase or frequency characteristics of the composite signal, distortions upon switching in the demodulated signal at low levels are eliminated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.