Method and apparatus for keying TV signals
US4951145A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 14, 1989 |
| Grant date | Aug 21, 1990 |
| Priority date | — |
| Expiry date | Sep 14, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/272
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for keying TV signals. A keying signal, K, is employed to create first and second modified keying signals, K(A) and K(B), which commence at independent points in time. The modified signals are compared and, as a result, a revised keying signal, R, is produced commencing at the leading edge of one modified keying signal and terminating at the trailing edge of the other. The operator selects R according to one of the two rules (i), (ii), the selection being by trial and error: PA0 rule (i): PA1 if K(A)>K(B) then R=K(A) PA1 if K(A)<K(B) then R=K(B) PA0 rule (ii) (which is the converse of rule (i)): PA1 if K(A)>K(B) then R=K(B) PA1 if K(A)<K(B) then R=K(A). In this manner, the revised keying signal R can be made to coincide with the video signal, V, to be keyed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.