Noise reduction circuitry for audio signals
US4462048A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 11, 1982 |
| Grant date | Jul 24, 1984 |
| Priority date | — |
| Expiry date | Feb 11, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/802
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A signal substitution system is employed in audio processing circuitry to compensate for impulse noise and signal dropouts. Stored or delayed audio signal is substituted in the IF portion of the receiver circuitry ahead of the IF filters thereby precluding the noise impulses from exciting the filters into a ringing mode and significantly broadening what are otherwise very narrow signal disturbances. To insure that the substitution signal is in relative phase coherence with the substituted signal, the substitution signal is delayed an integral number, N, of cycles of the audio carrier. The number N is chosen to be small, resulting in the change in the modulating signal corresponding to the stored portion of the carrier being small. The affect on the baseband signal is that during instances where defects occurred the signal appears to have been sampled and held, but the duration is so short that they are not audibly distinguishable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.