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:
Jan. 28, 1997
Filed:
Mar. 23, 1995
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A remote control access system uses a transmitter and a receiver. The transmitter generates an encrypted identification code which the receiver decrypts and grants access to the system if the decrypted code matches an identification code stored in the receiver. The encryption occurs by taking a 40 bit identification code and forming 5 bytes (8 bytes each). The 5 bytes are logic exclusive OR'd to form a 5 byte wide encrypted code. Decryption occurs by performing the opposite exclusive OR operation on the 5 byte wide encrypted code to convert it back to the 5 byte identification code. The 4 most significant bytes of the decrypted code are compared against the 4 most significant bytes of the previous stored decrypted code in the receiver. If the comparison yields a zero, this means the least significant byte will be within 2.sup.8 or 256 of each other and access will be granted.