Noise blanking circuit for AM stero
US5261004A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1991 |
| Grant date | Nov 9, 1993 |
| Priority date | — |
| Expiry date | Dec 17, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2001/1063
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An AM stereo input signal is processed by an envelope detector, an in-phase detector and a quadrature phase detector to yield outputs which may carry short noise impulses. Each output is low pass filtered to derive an average signal level and each output is ratiometrically compared to the corresponding average to detect a tic or modulation substantially above the average. In response to a tic a hold circuit generates a flag for a period which depends on the quality of the input signal. A dual mode deemphasis and sample/hold circuit normally filters the audio signal in each channel and is effective for the duration of the flag to hold the existing signal in the circuit to blank out the noise impulse.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.