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:
Jul. 17, 1990
Filed:
Dec. 06, 1988
Michel Imbert, Seyssins, FR;
Jean-Marc Merval, Saint Egreve, FR;
SGS-Thomson Microelectronics S.A., Gentilly, FR;
Abstract
A detection circuit for a video tape recorder signal on the input of a TV set connected to a line synchronization separating circuit (11) in turn connected to a PLL (12) comprises a first phase comparator (15), the PLL (12) exhibiting a first time constant (I1, C1) corresponding to an operation on a normal TV signal. This circuit further comprises a switch (20) for switching the PLL on a second time constant (3I1, C1) shorter than the first one, a second phase comparator (22) for comparing the input and output phases of the first phase comparator, the second phase comparator being associated with a third time constant (I2, C2) shorter than the first and second ones, a threshold comparator (24) supplying to the switch (20) a control signal when the comparator output (22) is outside determined limits.