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:
Jun. 05, 2012
Filed:
Nov. 30, 2005
Martin S. Wilcox, Redhill, GB;
Adam S. Leitch, Brighton, GB;
Martin S. Wilcox, Redhill, GB;
Adam S. Leitch, Brighton, GB;
Koninklijke Philips Electronics N.V., Eindhoven, NL;
Abstract
First and second devices having clocks which may have different clock rates. Obtaining a measure of the distance of propagation of a signal passing between the devices involves transmitting a first signalfrom the first device to the second device. After a turnaround time TAT, a second signalis transmitted from the second device to the first device. Any error in the clocks may lead to an error in the measurement of the turnaround time TAT. One device contains circuitry to calculate the ratio of the clock rates of the first and second devices, either by adjusting frequency divider ratios until there is LO frequency match, or by determining the offset frequency of an envelope of a mixed signal. The ratio of the clock rates is used to compensate the turnaround time TAT, to mitigate error. The accurate distance measurement can be used to determine if a relay attack has taken place in a vehicle security system.