Rolling code security system

• US 8,194,856 B2
• Filed: 07/22/2008
• Issued: 06/05/2012
• Est. Priority Date: 05/17/1995
• 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:
  US12/177,294
• Publication Number:
  US 20090016530A1
• Time in Patent Office: 1,414 Days
• Field of Search: 380/262, 380/239, 380/44, 726/44, 726 16- 17, 726 2- 4, 726 27- 30, 340/825.71, 340/825.72, 340/825.73, 341/173, 713/168
• US Class Current: 380/239
• CPC Class Codes: G07C 2009/00214 by one push button
• CPC Class Codes: G07C 2009/00253 dynamically, e.g. variable code - rolling code
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: H04L 2209/80 Wireless
• CPC Class Codes: H04L 2209/84 Vehicles
• CPC Class Codes: H04L 9/32 including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
• CPC Class Codes: H04W 12/02 Protecting privacy or anonymity, e.g. protecting personally identifiable information [PII]
• CPC Class Codes: H04W 12/033 of the user plane, e.g. user's traffic
• CPC Class Codes: H04W 12/80 Arrangements enabling lawful interception [LI]
• 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 wireless transmitter for sending a radio frequency signal to a wireless receiver to actuate an electric motor to open or close a movable barrier, the wireless transmitter comprising:

an end-user switch;

a radio frequency transmitter;

a control circuit operably coupled to the end-user switch and to the radio frequency transmitter, the control circuit being configured to respond to an end-user assertion of the end-user switch by causing the radio frequency transmitter to transmit the radio frequency signal, at least in part, as a rolling code, wherein the rolling code is modulated onto a radio frequency carrier using both amplitude modulation and pulse-width modulation.

2. The wireless transmitter of claim 1 wherein the amplitude modulation comprises bi-level amplitude modulation.

3. The wireless transmitter of claim 2 wherein the bi-level amplitude modulation comprises on/off keying.

4. The wireless transmitter of claim 1 wherein the pulse-width modulation comprises at least three different pulse widths.

5. The wireless transmitter of claim 4 wherein at least a portion of the rolling code comprises trinary-expressed information, such that there is a separate and discrete pulse width correlated to each trit of the trinary-expressed information.

6. A method comprising:

at a wireless transmitter;

detecting an end-user assertion of an end-user interface;

in response to detecting the end-user assertion, causing a radio frequency transmitter to transmit a radio frequency signal that comprises, at least in part, a rolling code, wherein the rolling code is modulated onto a radio frequency carrier using both amplitude modulation and pulse-width modulation.

7. A method of claim 6 wherein the amplitude modulation comprises bi-level amplitude modulation.

9. The method of claim 6 wherein the pulse-width modulation comprises at least three different pulse widths.

10. The method of claim 9 wherein at least a portion of the rolling code comprises trinary-expressed information, such that there is a separate and discrete pulse width correlated to each frit of the trinary-expressed information.

8. The method of 7 wherein the bi-level amplitude modulation comprises on/off keying.