Rolling code security system

• US 6,980,655 B2
• Filed: 10/17/2001
• Issued: 12/27/2005
• Est. Priority Date: 01/21/2000
• Status: Expired due to Fees

• Current Assignee: The Chamberlain Group, Inc. (The Chamberlain Group LLC)
• Original Assignee: The Chamberlain Group, Inc. (The Chamberlain Group LLC)
• Inventors: Fitzgibbon, James J., Farris, Bradford L.
• Primary Examiner(s): Song, Hosuk
• Application Number:
  US09/981,433
• Publication Number:
  US 20020034303A1
• Time in Patent Office: 1,532 Days
• Field of Search: 380/262, 380/239, 380/44, 380/46, 34082571-82573, 340/5.2, 340 521- 523, 340/825.75, 341/173, 341176-177, 375135-137, 375/295, 370/335, 713/200
• US Class Current: 380/262
• CPC Class Codes: G07C 2009/00214 by one push button
• CPC Class Codes: G07C 2009/0023 with encription of the transmittted data signal
• CPC Class Codes: G07C 2009/00238 the transmittted data signal containing a code which is changed
• CPC Class Codes: G07C 2009/00253 dynamically, e.g. variable code - rolling code
• CPC Class Codes: G07C 2009/00555 comprising means to detect or avoid relay attacks
• CPC Class Codes: G07C 2009/00587 by battery
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2009/00928 for garage doors
• CPC Class Codes: G07C 2209/06 Involving synchronization or resynchronization between transmitter and receiver; reordering of codes
• CPC Class Codes: G07C 2209/08 With time considerations, e.g. temporary activation, valid time window or time limitations
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: G07C 9/00817 where the code of the lock can be programmed
• CPC Class Codes: H04L 2209/80 Wireless
• CPC Class Codes: H04L 2209/84 Vehicles
• CPC Class Codes: H04L 9/3226 using a predetermined code, e.g. password, passphrase or PIN network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

A rolling code transmitter is useful in a security system for providing secure encrypted RF transmission comprising an interleaved trinary bit fixed code and rolling code. A receiver demodulates the encrypted RF transmission and recovers the fixed code and rolling code. Upon comparison of the fixed and rolling codes with stored codes and determining that the signal has emanated from an authorized transmitter, a signal is generated to actuate an electric motor to open or close a movable barrier.

Claims

1. A transmitter for sending an encrypted signal to control an actuator, comprising:

oscillator for generating a radio frequency oscillatory signal;

apparatus for enabling the sending of an encrypted signal;

binary code generator responsive to the enabling apparatus for generating a variable binary code, said variable code being different for each enabling by the enabling device;

multi-value digit code generator for generating a multi-value digit code responsive to the variable binary code, wherein each multi-value digit has four or more possible values; and

transmitting apparatus for modulating the radio frequency oscillatory signal with the multi-value digit code to produce a modulated multi-value digit coded variable radio frequency signal for operation or control of a secure actuator.

2. A transmitter for sending an encrypted signal to control an actuator according to claim 1, further comprising apparatus for receiving said variable binary signal and producing a mirrored binary signal, said mirrored binary signal being supplied to said multi-value digit code generator for generating the multi-value digit signal from the variable binary signal.

3. A transmitter for sending an encrypted signal to control an actuator according to claim 1, comprising apparatus for producing a fixed code signal and for combining said fixed code signal with a rolling code signal.

4. A transmitter for sending an encrypted signal to control an actuator according to claim 3, comprising apparatus for interleaving multi-value digits derived from said fixed code signal with multi-value digits derived from said rolling code signal to produce a multi-value digit interleaved fixed and rolling code signal.

5. A transmitter for sending an encrypted signal to control an actuator according to claim 1, comprising incrementing apparatus for altering said variable code by adding a fixed value with each enabling apparatus actuation.

6. A transmitter for sending an encrypted signal to control an actuator according to claim 5, wherein said means for incrementing said variable code increments said variable code by a prime number value.

7. A transmitter for sending an encrypted signal to control an actuator according to claim 1, wherein said binary code generator for generating a variable binary code includes a non-volatile memory for storing a variable binary code.

8. A transmitter for sending an encrypted signal to control an actuator according to claim 1, wherein said binary code generator for generating said variable code includes storage means holding a previous cycle variable code signal from which the variable code is generated.

9. A remote security system for communicating an encrypted signal to a control actuator, comprising:

binary code generator for generating a sequence of variable binary codes according to a predetermined algorithm, successive codes in the sequence being different from preceding codes in the sequence;

multi-value digit code generator for converting said generated variable binary code to a multi-value digit code, wherein each multi-value digit has four or more possible values;

a transmitter for modulating a transmitted radio frequency signal with said multi-value digit code;

a radio-frequency receiver for demodulating said transmitted modulated radio frequency signal and providing a received multi-value digit code;

multi-value digit code convertor for converting said received multi-value digit code to a received binary code;

a controller responsive to a positive comparison of said received binary code and a reference variable binary code; and

update apparatus responsive to said positive comparison for updating said reference variable binary code according to said received binary code.

10. A remote security system according to claim 9, wherein said update apparatus updates said reference variable binary code by performing said predetermined algorithm on said reference variable binary code.

11. A remote security system according to claim 9, wherein said positive comparison results if said received binary code and said reference variable binary code lie within a predetermined numerical limit of one another.

12. A remote security system according to claim 11, wherein said positive comparison results if the numerical difference of said received binary code minus said reference

variable binary code is a positive number less than said predetermined limit.

13. A remote security system according to claim 12, wherein said predetermined limit is about 1000.

14. A remote security system according to claim 12, wherein said positive comparison results if at least two said received binary codes transmitted in succession, each of which is numerically different from said reference variable binary code by a number outside the range of said predetermined limit, represent successive results of said predetermined algorithm.

15. A remote security system according to claim 14, wherein said positive comparison results if said successively transmitted codes which represent successive results of said preselected algorithm, each yield a difference when subtracted from said reference variable binary code outside the range of zero to a second predetermined limit.

16. A remote security system according to claim 15, wherein said second predetermined limit is about 300.

17. A remote security system according to claim 11, wherein the variable binary code is a rolling code and the system further comprises a binary code combiner for combining a binary fixed code with said binary rolling code and providing the combination to said multi-value digit code generator.

18. A remote security system according to claim 17, further comprising apparatus for interleaving multi-value digits derived from said binary fixed code with multi-value digits derived from said binary rolling code to provide an interleaved multi-value digit fixed-and-rolling code to said transmitter.

19. A remote security system according to claim 18, further comprising apparatus for receiving said output of said radio-frequency receiver, and separating said interleaved fixed-and-rolling code and providing to said multi-value digit code convertor a received multi-value digit fixed code and a received multi-value digit rolling code.

20. A remote security system according to claim 19, wherein said multi-value digit code convertor provides a received binary fixed code in response to said received multi-value digit fixed code and a received binary rolling code in response to said received multi-value digit rolling code, and further comprising addressing apparatus for using said received binary fixed code to address said reference variable binary code in a memory.

21. A remote security system according to claim 20, further comprising means for mirroring said binary rolling code and providing it to said multi-value digit code generator.

22. A remote security system according to claim 21, further comprising apparatus for mirroring said received binary rolling code and providing it to said controller and to said update apparatus.

23. A remote security system according to claim 22, wherein said predetermined algorithm generates a variable binary code by adding a numeric constant to it.

24. A remote security system according to claim 23, wherein said predetermined algorithm generates a variable binary code by adding the value 3 to it.

25. A remote security system according to claim 15, further comprising second update apparatus for updating said reference variable binary code according to one of the set of said successively transmitted received binary codes.