WO2000046955A1

WO2000046955A1 - Bi-directional coding system for remote control device security

Info

Publication number: WO2000046955A1
Application number: PCT/AU2000/000062
Authority: WO
Inventors: Campbell James
Original assignee: Australian Arrow Pty Ltd.
Priority date: 1999-02-05
Filing date: 2000-02-03
Publication date: 2000-08-10
Also published as: AUPP849299A0

Abstract

A security system for access control or other functional control for motor vehicles, buildings or other structures uses bi-directional coded signal transmissions. An identification device (1) ha s a transmitter (4) to transmit a first coded signal (20) to a receiver (8) in an operating module (7) associated with the vehicle, building or the like. The operating module (7), in response to the first coded signal (20), transmits a second coded signal (21) which may include a coded question (22). The identification de vice (1) receives the second coded signal (21, 22) and transmits a coded response signal (23) which is received and validated by the operating module (7). On validation, the operating module (7) activates appropriate access control or other functional operational control for the motor vehicle, building or the like, such as unlocking vehicle doors and enabling vehicle systems.

Description

BI-DIRECTIONAL CODING SYSTEM FOR REMOTE CONTROL DEVICE

SECURITY Field of the Invention

This invention relates to a bi-directional coding system for a remote control security device to improve the security of a radio, infra-red, ultrasonic microwave or other data transmission used, for example, for access or operational control applications such as for motor vehicles, building access, machine operation or the like.

Background of the Invention Access control systems or operational control systems which utilise a remote control device to transmit coded signals to a receiver may communicate by radio, infra-red, microwave or, in some cases, ultrasonic or other communication techniques. While the present invention will be particularly described with reference to a radio signal transmission, it will be understood that the invention may be utilised with other forms of signal transmission.

Concerns over the security of radio frequency signal transmission between a remote control device and an operating module, and particularly concerns over the interception of such signals by so-called "code grabbers" have led to the development of rolling code and code hopping strategies being employed in the more sophisticated systems whereby codes are changed after each actuation or transmission to prevent codes being intercepted and replicated and used by a "code grabber". However, the system must be sufficiently sophisticated to allow for transmissions not properly received by the receiver. In one arrangement, the receiver of the operating module monitors the codes which have been received and allows a "window" of codes after the last reception to allow for missed transmissions from the remote control device when the transmitter is operated whilst out of range of the receiver. As the transmitted code from the remote control device must be predictable by the receiver, a sophisticated code grabber that is able to analyse such a signal may be able to intercept such transmission and thereby predict the next legitimate code. A code grabber is then able to transmit the necessary code to obtain unauthorised access to or control the operation of a building, motor vehicle or machine. Some remote control devices use push-button radio transmissions to transmit the control code. However, push-button transmitters are not the most convenient solution for many applications. For some applications, such as access control for motor vehicles and buildings, radio beacon transmitters that typically emit a periodic transmission are a more convenient means of access control as they require no manual operation by the user. However, this transmission is usually a fixed code to distinguish one user from another and to allow access, disarming or other control as is appropriate. Where only a moderate level of security is required, and convenience is more important, such systems may be adequate. Such systems, however, are more prone to code theft by a code grabber who has many more opportunities to intercept signals than from conventional push-button transmitters as the beacon transmitters, are continually transmitting the security code.

In one proposal to avoid the difficulties associated with either push- button radio remote control device or the radio beacon transmitters, the battery powered remote control device has a low power receiver that listens for an activation code transmitted periodically from the operating module of the host system. Alternatively, the activation code may be transmitted when an access attempt is made, such as a person operating a motor vehicle door handle or a building door handle, or the like. The coded transmitted signal received by the low power receiver causes the remote control device to respond by transmitting a reply. By this means, the remote control device does not continuously emit a code and can even be programmed to emit different responses to different coded transmitted signals, thus making code interception very difficult. However, a difficulty with such a proposed system is that the receiver in the remote control device must essentially be permanently enabled so as to receive the coded transmitted signal at the time that it is transmitted. It is difficult to produce an ultra low power receiver that has sufficient sensitivity, so a trade off has to be made between the operating range of the system and the battery life in the remote control device, thereby restricting the application of such systems.

In a further proposal, the remote control device incorporates ^"a battery- less transponder and the operating module of the host system transmits not only a code but also the energy for the transponder. Low frequency activated devices are able to be made at a relatively low cost, but the device can only be read over relatively short distances approximately equal to the size of the reader. Microwave transponders can be read over greater distances, but are much more complex and consequently more expensive , and also often battery assisted. The microwave energising signal also needs, in most cases, to be directional to provide sufficient energy, again restricting its application to where the reader will be approached from a known direction, such as with a building application. Summary of the Invention

It is therefore desirable to provide a coding system for remote control security devices which obviates at least some of the disadvantages of prior systems.

It is also desirable to provide a coding system providing a high level of security for identification devices to actuate an operating system from a remote distance.

It is also desirable to provide a coding system which is able to be economically produced, which has relatively low power consumption and which is able to be operated over a moderate range. It is also desirable to provide an improved security system which is difficult, at least, to infiltrate.

According to one aspect of the invention there is provided a security system for access or other operational control associated with a building, motor vehicle, machine or other structure comprising: i) an identification device having a first transmitter means to transmit a first coded signal, a first receiver to receive a second coded signal and identification means to respond to the second coded signal with a transmitted coded response signal; ii) an operating module having a second receiver to receive the first coded signal, a second transmitter to transmit the second coded signal, a code generator means to randomly or pseudo-randomly generate codes forming at least part of said second coded signal, and a decoder means to decode and validate the coded response signal, whereby the operating module activates access control or other operational control associated with the building, motor vehicle, machine or other structure in response to the validated coded response signal.

In one preferred embodiment of the invention, the security system is used for access and operational control of a motor vehicle thereby permitting the driver to open vehicle doors and to activate the vehicle ignition and deactivate any vehicle disabling or alarm systems. In one embodiment, the first transmitter in the identification device transmits a first coded signal on a periodic basis, as is the case with radio beacon transmitters that typically emit a periodic transmission. While the first coded signal may be a fixed code, which may be consistent between a plurality of identification devices associated with the operating module, the second coded signal includes an activating code and a random question which is determined by an algorithm and constants known to the identification device and the operating module.

Preferably, the first receiver means is activated for a relatively small, predetermined period when the first transmitter means transmits the first coded signal. Alternatively, the first receiver may be activated prior to transmission of the first coded signal and if any other transmitted coded signal is received, the transmission of the first coded signal is delayed. The first coded signal is preferably only a brief signal, and the minimisation of transmission and receiver operating time substantially minimises power consumption. Further, the brief first coded signal minimises possible interference with coded signals of other systems.

The identification device may have actuating means, such as push-button switches, to initiate transmission of an encoded signal which may be the first coded signal, additional to that signal being transmitted periodically, or a different coded signal. With this arrangement, the transmission power of the first transmitter means may be increased by actuation of the actuating means thereby causing operation of the operating module at a range greater than would otherwise occur as a result of the periodic transmission of the first coded signal. In an alternate embodiment, the identification device transmits the first coded signal only after actuation of an actuating means, such as a push-button switch, on the device.

Where two or more push-button switches are incorporated into an identification device, each push-button may give rise to the transmission of different coded signals to control different functional aspects of the operational control associated with a building, motor vehicle, machine or other structure. For example, in relation to a motor vehicle, one push-button may control operation of front access doors only while another push-button may control operation of a rear door or trunk lid the motor vehicle.

The second receiver means associated with the operating module preferably detects the first coded signal as long as the identification device is within the range defined by the effective radiated power for the first transmitter means and the effective sensitivity of the second receiver means and associated antenna assembly in the environment in which it is used. If the operating module receives the first coded signal and determines that the identification device may be associated with it, the operating module transmits the second coded signal containing the activating code and the random question.

In one particular embodiment, to minimise power consumption of the identification device, and to maximise the available time for other identification devices to access the operating module, the operating module transmits the second coded signal, receives the response signal, and thereafter listens for continuing first coded signals from the identification device without retransmitting second coded signals. In this way, the operating module maintains identification of the identification device without requiring the identification device to continually transmit the response signal. The operating module simply listens for the subsequent first coded signals but does not respond thereto after reception of the response signal. Thus, the identification device does not waste power unnecessarily. If the operating module fails to receive a predetermined number of first coded signals during the monitoring operation, it will be assumed that the identification device has moved out of range and the operating module and re-operates the control mechanisms associated with a building, motor vehicle, machine or other structure to the secure mode. In a modification of this embodiment, and if determined necessary, the operating module may occasionally respond to a first coded signal from the identification device but with a different response message to ensure the continued integrity of the identification device.

A major advantage of the present invention is that it provides a very high level of security for beacon remote control devices that would otherwise employ fixed codes or time derived rolling codes. The invention also provides high levels of security for push-button actuated remote control devices. A higher level of security is required to enable broader application of such devices where the convenience of "hands free" operation is desired but security is a concern. The present invention enables achievement of this higher level of security.

A further major advantage of the present invention is that the power consumption of the remote control device, or identification device, is able to be kept to a minimum by powering the transmitter and receiver only briefly, except during the verification procedure. This means that simple receivers and transmitters that perform well, but would otherwise be impractical to use due to power consumption, are able to be utilised in the present invention thereby opening opportunities where the cost or size of more sophisticated transmitters and receivers or performance of lower powered transmitters and receivers make the application non- viable. The controller in the identification device is able to enter a lower power state while timing the intervals between transmissions, the timing of which need not be precise. It is sufficient that the transmission of the first coded signal occurs periodically.

In order that the invention is more readily understood embodiments thereof will now be described with reference to the accompanying drawings. Brief Description of the Drawings

Fig 1 is a schematic block diagram of an identification device in accordance with one embodiment of the present invention;

Fig 2 is a schematic block diagram of an operating module for use in this embodiment of the invention; and

Fig 3 illustrates the transmitted code exchange sequence between the identification device of Fig 1 and the operating module of Fig 2. Description of the Preferred Embodiment

Referring to the drawings, the system illustrated may be used for access or other operational control associated with a building, motor vehicle, machine or any other structure. However, for ease of description, the system will be described with reference to its use in relation to a motor vehicle. The system is designed to provide access control to the vehicle by unlocking and locking vehicle doors. The system may also be used to control operation of functional systems of the vehicle such as an alarm, the ignition system, fuel supply and other vehicle systems, thereby controlling vehicle security. In controlling the access to the vehicle, the vehicle doors are locked and unlocked by a door release solenoid 14 controlled by means of a driver 11. The driver 11 is operated by the operating module 7 according to the presence or absence of a valid data exchange between the identification device 1 and the operating module 7. In accordance with this embodiment, the identification device 1 is powered from a power source 2, such as a battery, that provides power to the controller 3, transmitter 4 and receiver 5. The controller 3 periodically sends an identification code 20 (Fig 3) via the transmitter 4 and activates the receiver 5 for a brief, predetermined period to detect any signal response. In this embodiment, a push-button 6 may be employed to manually effect the transmission of the identification code 20 and the brief powering up of the receiver 5.

If the identification device 1 is within range of the operating module 7, the identification code 20 will be received by the receiver 8 in the operating module 7 and checked to ensure that the code relates to the operating module 7. When validated, this gives rise to the transmission by the operating^" module transmitter 9 of a second coded signal 21. The second coded signal 21 is specific to the identification device 1 and is followed by a second signal part 22 comprising a random question developed by a code generator in the controller 10 of the operating module 7 which randomly or pseudo-randomly generates codes in accordance with a known algorithm and known constants to form part of the second coded signal 21.

The second coded signal 21 is received by the receiver 5 of the identification device 1 and is validated by the controller 3. The receiver 5 remains powered-up for a period long enough to receive the random question 22. The controller 3 then powers down the receiver, calculates the appropriate answer code 23 and transmits the answer code 23 by the transmitter 4 before returning to an idle state (device disabled) or awaiting a data transfer sequence.

The transmitted response signal 23 is received by the operating module receiver 8, and the signal is decoded and validated whereby the controller 10 activates the door release solenoid 14 by means of the driver 11. The controller 10 continues to drive the solenoid 14 while the first coded signal transmission 20 from the verified identification device 1 is detected by the receiver 8 and the controller 10. If the signal 20 does not remain detectable within a predetermined period, such as a period corresponding to that of several transmissions of the first code 20, the controller 10 turns off the driver 11 so that the solenoid 14 thereby re-locks the vehicle door. If the identification device 1 again comes into range as determined by the receipt of a valid first coded signal transmission 20, the verification process begins again.

In an alternative arrangement, the operating module 7 may initially respond to a transmission from an identification device 1 and then remain silent. The controller 3 of the identification device 1 will continue to periodically send an identification code 20 via the transmitter 4, and continues to briefly turn on the receiver 5 to detect any response. As previously described, the operating module 7 receives the valid identification code 20, and the controller 10 formulates a response code 21 and random question 22 for the particular identification device 1. The receiver 5 in the identification module T remains powered-up to receive the random question 22, and the controller 3 subsequently powers down the receiver 5, determines and transmits an answer code 23. Subsequent periodic transmissions from the identification device 1 are monitored by the operating module 7 but are not responded to. Thus, the receiver 5 in the identification device 1 remains in an inactive state apart from the initial power-up to receive a response signal.

Furthermore, the operating module 7 may occasionally, periodically respond to the identification device 1 and transmit a different random response code 22 to ensure the integrity of the identification device 1. It will be appreciated that multiple identification devices 1 may be used with one operating module 7. A major concern with multiple identification device is the likelihood of corrupted data being sent due to the interference from neighbouring identification devices. To avoid this, the controller 3 in the identification device 1 may power up the receiver 5 briefly before sending a periodic transmission. Once the receiver 5 is active, it can listen to or monitor other identification device. If there are signals present which relate to other identification devices, the controller 3 will not send the first coded signal 20. The controller 3 will transmit a coded signal once no other signals are present at the receiver 5. The system of the present invention provides a number of unique advantages and overcomes difficulties in complexity and operation of prior systems to which reference has previously been made. The embodiments described reduce the possibility of collision through the use of short transmissions except during verification and if the receiver is turned on before a transmission starts, the chance of a collision is further reduced. Thus, a large number of identification devices may be reliably monitored by the operating module 7, where frequent collision from simple periodic transmission would otherwise exist thus severely limiting the number of identification devices that may co-exist. The present invention also avoids the problems associated with unidirectional systems such as may typically be used in beacons or push-button remote controls. Still further, data may be exchanged between the identification device 1 and the operating module 7 which can be stored and retrieved at a later time for actuation of the verification, decoding and transmission of response signals.

Claims

Claims:

1. A security system for access or other operational control associated with a building, motor vehicle, machine or other structure comprising: i) an identification device having a first transmitter means to transmit a first coded signal, a first receiver to receive a second coded signal and identification means to respond to the second coded signal with a transmitted coded response signal; ii) an operating module having a second receiver to receive the first coded signal, a second transmitter to transmit the second coded signal, a code generator means to randomly or pseudo-randomly generate codes forming at least part of said second coded signal, and a decoder means to decode and validate the coded response signal, whereby the operating module activates access control or other operational control associated with the building, motor vehicle, machine or other structure in response to the validated coded response signal.

2. A system according to Claim 1 wherein said first transmitter means transmits a first coded signal periodically.

3. A system according to Claim 1 or Claim 2 wherein said first transmitter means transmits a first coded signal in response to operation of an actuating means on the device.

4. A system according to any one of Claims 1 to 3 wherein said first receiver means is activated for a predetermined period when the first transmitter means transmits the first coded signal.

5. A security system according to Claim 4 wherein the predetermined period is extended if a second coded signal is received.

6. A system according to Claim 5 wherein said second coded signal includes an activating code and a random coded question.

7. A system according to Claim 6 wherein said coded response signal includes a response to the coded question as determined by an algorithm and constants known to the device and the operating module.

8. A system according to Claim 2 wherein activation of access control or other operational control by the operating module ceases when the periodically transmitted first coded signals are not received by the second receiver within a predetermined period.

9. A system according to Claim 8 wherein said predetermined period corresponds to that of several periodic transmissions of the first coded signal.

10. A system according to Claim 1 wherein said first receiver is activated prior to the transmission of the first coded signal to detect transmission of other coded signals by other identification devices which, if detected, causes the first transmitter means to delay transmission of the first coded signal.

11. A system according to Claim 1 wherein the first coded signal is a fixed code.

12. A system according to Claim 1 wherein the first coded signal is a rolling code.

13. A system according to Claim 3 wherein said actuating means comprises one or more push-button switches.

14. A system according to Claim 13 wherein operation of said actuating means causes transmission of a further coded signal to effect a different access control or other operational control.

15. A security system according to Claim 1 wherein after transmission of a second coded signal, the operating module continues to monitor receipt of first coded signals from the identification device without transmitting further second coded signals.

16. A security system according to Claim 1 wherein after transmission of a second coded signal, the operating module continues to monitor receipt of first coded signals from the identification device and transmits second coded signals with random codes at predetermined intervals to check the authenticity of the received first coded signals.

17. A security system substantially as hereinbefore described with reference to the accompanying drawings.