The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 01, 1992
Filed:
Mar. 06, 1991
Heinz Hess, Weiterstadt, DE;
BTS Broadcast Television Systems GmbH, Darmstadt, DE;
Abstract
When two color television standards prescribe the same horizontal scanning frequency but different color carrier frequencies, one of them, for example, requiring a frequency providing a one-half line offset to the horizontal scanning frequency (NTSC Standard) and the other requiring a three-quarter line offset (PAL-M Standard), each color carrier frequency being locked to the common line frequency, a modified phase locked loop circuit makes it possible to synchronize the color carrier frequencies to each other. The oscillator at the color carrier frequency of one standard has its output compared, in a phase comparison stage, with the color synchronization signal of the other standard. The output of the phase comparison stage is supplied to a sample-and-hold circuit which is sampled during the presence of that color synchronizing signal in every fourth line. The content of the sample-and-hold circuit is passed through a low-pass filter and then supplied to the control input of the oscillator, thus locking the latter to the color carrier of the other standard.