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:
May. 05, 1992
Filed:
Apr. 30, 1991
David L Hershberger, Nevada City, CA (US);
The Grass Valley Group, Nevada City, CA (US);
Abstract
A voltage controlled reference oscillator with a high Q and narrow tunability bandwidth produces an output oscillator frequency which is frequency divided by four alternative constants to produce four different clock frequencies for four different digital video standards, D1 component at 270 MHz, NTSC D2 composite at 143 MHz, D2 composite at 177 MHz, and a proposed new composite video standard that is to operate at a 360 MHz clock rate. Automatic identification of which serial digital video is present is accomplished by having the clock generator produce a clock signal at the frequency required by one of the video formats while a phase lock loop attempts to lock onto the incoming signals at that frequency. If no lock occurs within a predetermined time interval, the clock generator is made to produce a clock signal at the frequency required by a different one of the video formats and the phase lock is attempted again. This is repeated until a lock is attained. Optionally, when a lock occurs, the video is tested for validity within the format that is consistent with the clock frequency that produced the lock.