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:
Apr. 01, 1997
Filed:
Nov. 07, 1995
Siemens Aktiengesellschaft, Munich, DE;
Abstract
An anti-theft system for a motor vehicle includes a portable transponder carrying code information. A stationary transceiver has an oscillator and an oscillating circuit being excited to oscillate by the oscillator at an oscillation being modulated by the transponder in synchronism with the code information. A demodulator demodulates the modulated oscillation of the oscillating circuit. According to one embodiment, the code information is obtained from the demodulated oscillation by sampling the oscillation at least at one predetermined sampling time. An arithmetic unit compares the code information with command code information and transmits an enable signal to a security unit if a match occurs. The modulated oscillation being shifted by a predetermined phase angle is sampled once again if initially no code information is recognized from the demodulator. According to another embodiment, the modulated oscillation containing the code information is sampled at least at two predetermined times being phase-shifted from one another by a predetermined phase angle and the code information is obtained from voltage values detected at the sampling times. The arithmetic unit compares the code information with the command code information and transmits an enable signal to a security unit if a match occurs.