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. 14, 1999
Filed:
Jan. 29, 1998
Jos Scheelen, Mol, BE;
Abstract
In a bandpass filter, a first cyclical analogue signal V3 at a center frequency divided by integer N in divide 44 and the divided signal supplied to a digital filter 48 as its system clock; a second cyclical analogue signal at a frequency, to be measured, differing by a small amount from the center frequency, is delayed by N cycles by a dynamic store 54; a substractor 56 subtracts the second signal from the delayed second signal and supplies any difference to the digital filter 48; the output of the digital filter is related to the frequency of the second signal, but the center frequency is suppressed. The filter may be used in an interrogation for an electronic detection system in which an interrogation signal is modified in frequency by a small amount, characteristic of a device to be detected.