Method and apparatus for removing pseudo-sync and/or agc pulses from a video signal
US4695901A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 4, 1986 |
| Grant date | Sep 22, 1987 |
| Priority date | — |
| Expiry date | Mar 4, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91314
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Added pseudo-sync pulses and AGC pulses are removed from a video signal to enable acceptable video recording thereof. The added signals previously interfered with acceptable video recording of the video signal because the automatic gain control of videotape recorders sensed false recording levels, while conventional televisions receivers were unaffected by those modifications to the video signal. Removal of the added pulses permits acceptable video recording of the previously modified video signal. A selectively-operable clipping circuit is used to remove selected negative-value components (i.e. pseudo-sync pulses) from the video signal, while added AGC pulses are effectively blanked from the video signal with an electrically-operable switch. Both the blanking and clipping functions are selectively achieved by sensing both the normal sync pulses of the video signal and the added pseudo-sync pulses. Method and apparatus are disclosed for "cleaning up" video signals modified by either the pseudo-sync pulses alone, the AGC pulses alone, or combinations thereof.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.