Remote controlled garage door opening system

• US 6,049,289 A
• Filed: 09/06/1996
• Issued: 04/11/2000
• Est. Priority Date: 09/06/1996
• Status: Expired due to Term

• Current Assignee: Microchip Technology Incorporated, Overhead Door Corporation (Sanwa Holdings Corp.)
• Original Assignee: Microchip Technology Incorporated, Overhead Door Corporation (Sanwa Holdings Corp.)
• Inventors: Bruwer, Frederick J., Marneweck, Willem J., Waggamon, Dennis W., Delport, Vivien N.
• Primary Examiner(s): Williams, Howard L.
• Assistant Examiner(s): JEANGLAUDE, JEAN BRUNER
• Application Number:
  US08/706,682
• Time in Patent Office: 1,313 Days
• Field of Search: 340/825.31, 340/825.69, 340/825.72, 340/825.34, 340/825.22, 340/825.56, 341/176, 341/173
• US Class Current: 340/5.23
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 19/28 using pulse code
• CPC Class Codes: G08C 2201/62 Rolling code
• CPC Class Codes: H04J 13/0074 Code shifting or hopping
• CPC Class Codes: Y10T 70/5973 Remote control

Abstract

A remote control system for opening and closing a barrier, such as a garage door, includes an RF receiver and a plurality of RF transmitters. The transmitters and receiver include circuitry programmed to provide transmission of encrypted code signals each time the transmitters are used and employing a code hopping method which prevents unauthorized signal interception or code "grabbing". The system is operated in a code learning mode for the receiver by momentarily actuating a receiver learn mode button for receiving each transmitter identification code and a secret decryption key for that transmitter with the system automatically returning to the operate mode. Each transmitter identification and secret key code signal is automatically and randomly stored in an available and unused memory in the receiver circuitry. A multibit hopping code is transmitted from each transmitter to the receiver with each transmitter operation in the operate mode of the system and the hopping code changes with each transmission to prevent theft or code grabbing and resultant unauthorized operation of the system.

Claims

1. A remote controlled garage door opening and closing system, comprising:

(a) a set of multiple radio frequency transmitters from a designated manufacturer represented by a manufacturer'"'"'s key, each transmitter of said set having stored therein a transmitter identifying code comprising a serial number code portion unique to that transmitter, a secret key code portion unique to that transmitter, a synchronization value code portion which increments each time the transmitter is actuated, and a non-linear function generator for generating a multi-bit hopping code which changes each time the transmitter is actuated, each transmitter transmitting a coded signal representative of the hopping code and the serial number code portion;

(b) a receiver comprising a microprocessor operable between a learn mode and an operate mode, and memory having discrete locations for storing information respectively corresponding to each transmitter;

(c) said receiver having said manufacturer'"'"'s key stored in the receiver at the factory, the receiver receiving the hopping code and the serial number code portions transmitted during the learn mode, with said stored manufacturer'"'"'s key and the received serial number code portion associated with a transmitter used to independently generate in the receiver a secret key, and thereafter a synchronization value, corresponding to the secret key code portion and synchronization value of the particular transmitter;

(d) processing circuitry within the receiver storing, during the learn mode, the so-generated secret key and so-generated synchronization value, randomly in an unused discrete memory location, or if all said discrete memory locations are used, then by replacing the information in the randomly chosen memory location with the new information; and

(e) said receiver, during the operate mode, (i) performing a non-linear decoding function on the intercepted hopping code using one of said stored secret keys, thereby to generate a second synchronization value, (ii) comparing said second synchronization value with said stored synchronization value and generating a command signal when said second synchronization value bears, and is within a window of, a predetermined relationship with said stored synchronization value (iii) in the absence of said predetermined relationship, performing another non-linear decoding function on the intercepted hopping code using a different one of said stored secret keys to generate another second synchronization value, and (iv) continually repeating the sequence until a second synchronization value is found which bears the said predetermined relationship with said stored synchronization value.

2. The system as defined by claim 1 in which the secret key code portion unique to each transmitter is generated as a non-linear function of the serial number code portion and the manufacturer'"'"'s key.

3. The system as defined by claim 1 in which the serial number code portion plays no role during the operate mode.

4. The system as defined by claim 1, further comprising a mechanism operably connected to a garage door to open or close said door in response to said command signal.