GB2275552A

GB2275552A - A system for the remote operation of a security device

Info

Publication number: GB2275552A
Application number: GB9303780A
Authority: GB
Inventors: Kevin Trevor Talbot
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1993-02-25
Filing date: 1993-02-25
Publication date: 1994-08-31
Anticipated expiration: 2013-02-25
Also published as: GB9303780D0; GB2275552B

Abstract

The system comprises a transmitter 23 for transmitting an activation 32a or deactivation 32b signal and a receiver 21 for receiving the transmitted signals. The transmitter includes code generators 26, 27 operable in response to a control logic 28. The activation signal comprises a first code and an activation identity part for activating the security device e.g. lock. The de-activation signal comprises a second code and a de-activation identity part for de-activating the security device. At least one of the first and second codes is a rolling code. <IMAGE>

Description

A SYSTEM FOR THE ACTIVATION OR DE-ACTIVATION OF A SECURITY DEVICE The invention relates to a system for the activation or de-activation of a security device. In particular, but not exclusively, the invention is concerned with the remote operation of a vehicle door lock.

The remote operation of vehicle door locks has gained popularity over the last few years and is becoming available on an increasing number of vehicles. A typical remote control arrangement for locking and unlocking a vehicle door takes the form of a hand held transmitter which operates a receiving device in the vehicle. More recently, car thieves have been using electronic devices (known as code grabbing devices) capable of receiving a signal transmitted from a hand held transmitter and recording the signal. The recorded signal can subsequently be used to unlock the vehicle after the user leaves an area where the vehicle is parked.

A basic lock/unlock system for a vehicle utiiises a single fixed code 10 as shown in Fig.l which is transmitted both to lock and unlock the vehicle. It has been found relatively easy to receive and reccrd such a code for subsequent unlocking of the vehicle. In a slightly more secure system shown in Fig.2, the transmitted signal includes a fixed code 11 and a portion in the form of a lock/unlock bit or bits 12.

However, once the code 10 has been recorded by a code grabbing device, a thief can change the lock command bit or bits 12 to an unlock command and unlock the vehicle.

An object of the present invention is to provide a system whch will make it more difficult for a car thief to use transmitted signals to advantage.

According to the present invention there is provided a system for activation or de-activation of a security system comprising a transmitter for transmitting activation or de-activation signals and a receiver for receiving the signals, the transmitter including a code generator means operable in response to a control logic the activation signal comprising a first code and an activation identity part for activating the security system and the de-activation signal comprising a second code and a de-activation identity part for de-activating the security system, at least one of the first and second codes including a rolling code.

In that way, recording any number of the transmitted activation signals with a code grabbing device will not provide a thief with information to enable a signal to be generated which can de-activate the security system.

The activation signal may include a rolling code which many be many, e.g., thousands of changes behind the second code. Normally the codes are advanced each time they are used which will mean that the activation signal code can always remain the same number of changes away from the de-activation signal code.

The transmitter when used for activation may transmit the activation signal code and certain other transmitted information in a particular order whilst, when used for de-activation, the transmitter may transmit the de-activation signal code and other information in a different order.

In another case, as security is primarily require for de-activation, the rolling code may be used or de-activation only and a different type of code use for the activation.

A system for the remote operation of a lock in accordance with the invention will now be described by way of example with reference to the remaining accompanying drawings in which Fig.3 shows a transmitter/receiver arrangement for operating the door of a vehicle in accordance with the invention and Fig.4 illustrates locking and unlocking transmitter signal arrangements in accordance with the invention.

A vehicle 20 is provided with a door lock 22 actuated by a receiver 21 which can be remotely operated by means of a hand held transmitter 23. The transmitter 23 has a lock button 24 and an unlock button 25.

The transmitter 23 includes two rolling code generators 26, 27 which operate in response to a control logic unit 28 and the pressing of the respective buttons 24, 25.

The control logic unit 28 and the roiling code generators 26, 27 provide inputs to a transmitter circuit 30 enabling the transmitter to produce either a lock signal 32a or unlocked signal 32b depending upon which of the lock and unlock buttons 24, 25 is pressed.

On pushing the lock button 24, the transmitted signal 32a, represented diagrammatically in the upper half of Fig.4, comprises a rolling code 33, the transmitter identity 34, functional identity 35 (in this case to lock the vehicle) and a fixed code 36, e.g., a vehicle identity number or pseudo randomly programmed code. The receiver 21 receives the locking signal 32a and locks the vehicle door.

To unlock the vehicle, the unlock button 25 is pressed to produce the unlock signal 32b. In that case, the rolling code 40 is significantly different from the rolling code 33, the transmitter identity 34 and fixed code 36 remaining the same with an unlocking function 35b. The receiver 21 receives the unlocking signal 32 and unlocks the vehicle door.

The rolling code 33 can be of a completely different nature or length from the rolling code 40 or they can be codes which are arranged in the same sequence but one of which is many changes, e.g., several thousand behind the other.

As an alternative, the portions 33, 34, 35a, 36 of the transmitted signal 32a can be transmitted in one order whilst the portions 40, 34, 35b, 36 of the transmitted signal 32b could be transmitted in a totally different order. If desired, the order could vary randomly from transmission to transmission.

The receiver 21 can include its own rolling code generates similar to those 26, 27 in the transmitter to produce codes to compare with the transmitted codes for checking validation of the transmitted commands. On receiving valid commands, the receiver will cause the lock 22 to operated.

If desired, the length of the transmitted signals can vary from transmission to transmission.

As high security is required primarily for unlocking the vehicle, the transmitted locking signal 32a may include, say, a simple fixed code instead of a rolling code dispensing with the need for a second rolling code generator in the transmitter. The rolling code 40 which will always be significantly different from fixed code 33, can then be used in the unlocking signal 32b. If a code grabbing device were used to record the unlocking rolling code 40, there is every likelihood that the user will then immediately drive the vehicle away and should it return to the original parked position and be left in the locked condition by the user, it will have been locked and unlocked several times in the intervening period so that the unlocking rolling code 40 will have moved on far enough for the recorded code to be of no use to the thief.

The term security system" used herein embraces a lock, alarm, vehicle immobiliser, latch release or similar security device. In that respect the term "activation" will include locking of a lock, arming of an alarm and enabling of a vehicle immobiliser respectively. The term "de-activation" will include unlocking of the lock, disarming of the alarm, disabling the vehicle immobiliser and releasing of the latch respectively.

The term "transmitter" used herein includes a sender device which will transmit a radio signal, electromagnetic radiation, e.g., infra re, signal or a sender device which is directly wired to the receiver by means of an electrical connection, e.g., a plug-in sender module.

Claims

1. A system for activation or de-activation of a security device comprising a transmitter for transmitting activation or de-activation signals and a receiver for receiving the signals, the transmitter including a code generator means operable in response to a control logic, the activation signal comprising a first code and an activation identity part for activating the security system and the de-activation signal comprising a second code and a de-activation identity part for de-activating the security system at least one of the first and second codes including a rolling code.

2. A system according to Claim 1 in which both the first and second codes include rolling codes.

3. A system according to Claim 2 in which one of the rolling codes lags behind the other rolling code or is a code of a different sequence and/or length from the other.

4. A system according to any preceding Claim in which the transmitter may transmit each of the. first and second codes with other information, the transmitted matter forming the de-activation signal being in a different order from that forming the activation signal.

5. A system according to Claim 1 in which the rolling code is used for de-activation only.

6. A system according to any preceding Claim in which the security system includes a door lock of the vehicle.

7. A system according to any preceding Claim in which the transmitter is of a hand held type or a plug in module.

8. A system for the remote operation of a security device constructed and arranged substantially as described herein with reference to Figs.3 or 4 of the accompanying drawings.