AU615798B2

AU615798B2 - Alarm control system

Info

Publication number: AU615798B2
Application number: AU41742/89A
Authority: AU
Inventors: Peter Samuel Vogel
Original assignee: Right Hemisphere Pty Ltd
Current assignee: Individual
Priority date: 1988-09-30
Filing date: 1989-09-26
Publication date: 1991-10-10
Anticipated expiration: 2009-09-26
Also published as: AU4174289A

Description

PATENTS ACT 1952 COMPLETE SPECIFICATfp 7 9 41

(ORIGINAL)

FOR OFFICE USE Short Title: Int. CI: Application Number: Lodged: Complete Specification-lodged: Accepted: Lapsed: Published: Priority: 0:00 Related Art: 00~ I it t Name of Applicant: Right Hemisphere Pty Limited ttt Address of Applicant: 28 Adeline St-_xzct, Faulconbridge, NSW 2776 Actual Inventor: Peter Samuel Vogel Address for Service: 28 Adeline Street, Faulconbridge, NSW 2776 Complete Specification~ for the invention entitled: ALARM CONTROL SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me.

S010369 26/09/ C-9 acsc2209 The present invention relates to electronic alarm systems, and in particular, schemes for arming and disarming burglar alarms.

Burglar alarms are used to warn of unauthorised intrusion into premises, or property such as motor vehicles. They generally operate by causing an audible signal when a person is detected in a protected area, or when an electronic sensor, such as a switch attached to a door or an infra-red sensor mounted in the protected area, is activated by a suspected intruder.

One of the major difficulties of burglar alarms is provision of means whereby the alarm can be armed (put into the state where an intrusion will cause an alarm) and disarmed (put into a dormant state) by authorised persons, without the disarming means being subject to unauthorised use by a would-be intruder.

A number of schemes are commonly used for this purpose.

One widely-used system uses entry and exit delays, so that on leaving the protected area, the user operates a switch, and the alarm does not arm until some predetermined time later, say thirty seconds, during which period the alarmed area must be vacated to avoid triggering the alarm. On detection of a suspected intruder, the alarm is arranged so as not to sound for a predetermined period, during which an authorised user must I operate a switch to disarm the alarm. This scheme has proven unsatisfactory as it allows an intruder a period in which to locate

I

the alarm and disarm it by operating the switch or destroying the unit, without the alarm sounding. It also requires the user to I operate the disarm switch immediately on return to the area, acsc2209 2 LI- arsu~ with the result that use of such alarms causes undue inconvenience and occasional false alarms.

A better scheme, now widely used with car burglar alarms in particular, uses a remote control device to arm and disarm the alarm from outside the protected area. The user carries a small transmitter, usually operating with radio or infra-red signals, which is used to control the alarm unit once the protected area of the car has been vacated. On return to the car, the user uses the transmitter again to disarm the alarm. This scheme is convenient in that no delay is required on exit, and the alarm is immediately disarmed prior to entry.

Although remote controlled alarms have gained widespread a o acceptance, they suffer a serious shortcoming in that if the 414) remote control malfunctions, or the transmitter is lost, the car owner cannot re-enter the car without setting off the alarm. To alleviate this problem, some alarms are equipped with a keyswitch to disable the alarm in such emergencies, but this significantly detracts from the security of the system, and is also no help if the key has been lost. Another attempt to solve this I,'l 20 problem has been provision of a numeric keypad inside the car, ,00 by means of which a secret code number can be entered to t disable the alarm in case of malfunction or loss of the transmitter. This is more satisfactory, but suffers from the 0 01 o 004 disadvantage that such keypads are large and are difficult to 25 mount in a suitably-accessible and visible position within the car.

The cost of the keypad and associated electronics and wiring is also significant.

The present invention is directed towaru. providing new and useful alternatives to known arrangements for disabling alarms.

acsc2209 3 According to the present invention there is provided a method of disabling an alarm comprising the steps of detecting repeated operation of a switch, measuring the time intervals between said operations, forming a series of numbers based on the relative intervals between said operations, comparing said series of numbers with a series of numbers stored within the alarm, and disabling the alarm if the formed series of numbers equals the stored series of numbers.

In another aspect, the invention consists in alarm means comprising at least one switch, a detector equipped to detect repeated operation of said switch or switches, timing means equipped to measure the time intervals between said operations, k and control means equipped to form a series of numbers based 08 on the relative intervals between said operations and compare said series of numbers with a series of numbers stored within the alarm, and means to disable the alarm if the formed series of numbers equals the stored series of numbers.

A particular embodiment of the invention will now be 6 40 described, by way of example only, with reference to the drawings in which:- Fig. 1 is a schematic block diagram of this embodiment; and Fig. 2 is a flow diagram of the software used to decode the code number.

Referring to Fig. 1, the block diagram of this embodiment can 0 0 A 25 be seen to be that of an alarm suitable for a car burglar alarm,.

The alarm of this embodiment utilises a microcomputer, microcomputer 1, which in this embodiment is a Motorola MC1468705F2 device being chosen for its low power t acsc2209 4 consumption and ease of programming, although many other devices are equally well suited to this application.

Input conditioner 2 comprises interfacing circuits suitable for connection of alarm sensors, via sensor inputs 3, to the input ports of microcomputer 1. Typical sensors include door switches and motion detectors.

Siren controller 4 interfaces an output of microcomputer 1 to siren output 5, which causes .he alarm siren to sound when so instructed by microcomputer 1.

Other inputs connected to microcomputer 1 include ignition circuit 6, which is activated when the car's ignition is switched on, and valet switch 9, a two-position toggle switch the function of which is described fully below.

Radio receiver 7 also connected to an input of microcomputer 1 so that when a signal is received from a remote control transmitter (not shown) via antenna 8, the demodulated signal can be read by microcomputer 1.

I The alarm of this embodiment incorporates what is known as t 4 "passive arming", that is, the alarm automatically arms when the 4• 1 20 ignition has been switched off, a door switch operated, and a prescribed time has elapsed. This is achieved by suitable oo software executed by microcomputer 1.

o, Valet switch 9 is provided so that in cases where such passive arming is not desired, the function can be disabled by operating the switch before leaving the car. Valet switch 9 also serves a secondary function in this embodiment, namely as an emergency disabling means in case of radio control failure.

The software of microcomputer 1 is arranged so that valet switch 9 will only prevent passive arming if operated before the acsc2209 5 car door has been opened, so that it cannot be used by a thief to disarm the alarm after the owner has left. However, for the purpose of providing the emergency disarming function, further software is provided for detecting the operation of valet switch 9 according to a pattern known only to the authorised user. This software is shown schematically in the flow diagram of Fig. 2. In this embodiment a three digit code is used, and is entered by toggling valet switch 9 the number of times dictated by each digit of the code in turn, the end of each digit being indicated by a pause in toggling of greater than one-half of a second. For 0, 0 aexample, if the code number is 312, the sequence of operation of o valet switch 9, which for the sake of this example is assumed to ,obe in the UP position on entry to the car, would be as follows: DOWN, UP, DOWN Pause for at least one half of a second

UP

4,44 S: Pause for at least one half of a second DOWN, UP Pause for at least one half of a second 4'The alarm is then disarmed. In this embodiment, the alarm S' is arranged to sound the siren immediately on detection of intrusion, so that the likelihood of an intruder disabling the alarm before the siren sounds is minimised. A consequence of this is that in the event of loss of the remote control or malfunction, the car pwner must enter the car, causing the alarm to sound, and enter the code number as described above. If acsc2209 6 desired, an entry delay can be used to allow a few seconds to enter the code.

Referring now to Fig. 2, on entry to this software routine (for example when intrusion has been detected and the alarm has not been disarmed by the remote control), the following steps are followed: 1. Two registers are cleared. These are COUNT and DIGIT POINTER. COUNT is used to accumulate switch activations for each digit entered, DIGIT POINTER is used to step though a table in which the code number is assembled digit by digit. In this embodiment this table comprises three bytes.

2. The state of the valet switch is tested, and, after allowing suitable debouncing delays, compared with the previous state.

o This loop is repeated until the state has changed.

15 3. When a state change is detected, a timer (in this case a free-running timer which is part of the microcomputer device) is read. The time read is compared to the time read on detection of o the previous switch state change.

4. If the difference is less than one half of a second, the state 0"o 0 20 change is considered a part of a digit being entered and accordingly the accumulator COUNT is incremented and the loop repeated as shown. If the difference is greater than one half of a second, the state change is considered to be the pause between digits. In this case, the COUNT register is stored in the table, the COUNT register is cleared ready for the next digit to commence, and the DIGIT POINTER is incremented.

A test is performed to see if the value of the DIGIT POINTER is now three. If not, the pregramme loops as shown.

acsc2209 7 IrPr

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0 0 090 a*00 00*1ir 0 a0 Oa 0I a oa a 0 *8 I 0 Ia a 4*( a a 6. If the value of the DiGIT POINTER is now three, indicating that all three digits of the received code number have been received and stored in the table, the three digits of the table are compared to a number stored in non-volatile memory (NV memory). If the numbers are not equal, the DIGIT POINTFR is cleared and the process repeats. If the numbers are equal, a signal is generated to disarm the alarm and the routine exits.

The foregoing describes only one embodiment of the present invention, and changes, obvious to those skilled in the art, can be made without departing from the scope of the invention. For example, whereas the switch used for entering the code number is described as being a toggle switch, other types of switch, such as push-button, can be used. It is also envisaged that the switch 15 can be of a non-mechanical type, for example an optical sensor or a proximity sensor. Furthermore, although the valet switch is used in the exemplary embodiment, a switch specially provided for the purpose of disarming the alarm according to this invention can be used, or any other switch already used for another purpose can be used. For example, in a motor vehicle, the brake warning light switch can be used to serve the secondary function of this invention, so that in the event of remote control failure, the alarm can be disarmed by operating the brake pedal according to the code number. In the case of a house burglar alarm, a light switch can be used in the same way.

acsc2209 8

Claims

2. A method of disabling an alarm system according to claim 1 wherein forming a series of numbers based on the relative time intervals between said operations comprises the sub- steps of: measuring the time intervals between two successive switch operations; comparing the magnitude of said time interval to a predetermined threshold; classifying the iterval as short if it is smaller than said threshold; classifying the interval as long if it is greater than said threshold; counting the number of successive short intervals to form a digit; restarting counting on detection of a long interval; and ,Y acsc7/91 9 Its; a forming further digits by repeating these substeps.
3. An alarm system comprising: at least one switch; i a detector equipped to detect repeated operations of said switch or switches; timing means equipped to measure the time intervals between said operations; control means equipped to form a series of numbers based on the relative time intervals between said operations and compare said series of numbers with a series of preset numbers; and means to disable the alarm if the formed series of numbers equals the stored series of numbers. S4. An alarm system according to claim 3 wherein said control means comprises: timing means adapted to measure the time intervals between ii two successive switch operations; i 20 means for comparing the magnitude of each time interval to a predetermined threshold and classifying the time interval as short if it is smaller than said threshold and as long if it is greater than said threshold; and j means for counting the number of successive short time intervals to form a digit and restarting counting on detection of a long time interval. An alarm system according to claim 3 or 4 wherein in addition to providing signals for disabling an alarm system, acsc7/91 1C said switch is used to operate apparatus other than an alarm H system.
6. An alarm system according to claim 3 or 4 wherein said switch is provided only for the purpose of disabling the alarm system.
7. An alarm system according to any of claims 3 to 6 wherein said switch is a mechanical switch.
8. An alarm system according to any of claims 3 to 6 wherein said switch is a sensor which can be actuated without i physical contact.
9. An alarm system according to claim 3 or claim 4 wherein the control means comprises a microcomputer. An alarm system substantially as hereinbefore described with reference to Figures 1 and 2. Dated this TWENTY SECOND day of SEPTEMBER, 1989 RIGHT HEMISPHERE PTY. LIMITED acsc7/91 11