GB2400711A

GB2400711A - Wireless alarm system monitoring the position of valuables that is suitable for protecting computers or mobile phones which are using wireless data networks

Info

Publication number: GB2400711A
Application number: GB0308883A
Authority: GB
Inventors: Paul Thomas Dimmer; Anthony Haddrell; James Douglas Manser
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-04-16
Filing date: 2003-04-16
Publication date: 2004-10-20
Also published as: GB0308883D0

Abstract

An alarm system for protecting movable entities such as personal valuables has a master unit and a number of slave units. The master unit (11) has a transceiver for wireless communication with the slave units (14, 15, 16), and each slave unit includes a transceiver for wirelessly communicating with the master unit. The system includes a separate detector responsive to signals transmitted between the master unit and each slave unit to produce a separation signal when the transmitted signals are indicative of one or more of the slave units having become separated from the master unit. An alert generator, in the form of an audible or visual alarm, is coupled to the separation detector and arranged to generate and alert in response to the separation signal. In this way, the system activates an alert when a movable entity such as a mobile telephone or laptop computer, is separated from its owner.

Description

1 240071 1

ALARM SYSTEM

This invention relates to an alarm system for protecting movable entities such as personal valuables. The system activates an alert when an entity, such as a mobile phone or laptop, is separated from its owner.

It is known to fix a radio transmitter to a valuable item and to place a radio receiver with the owner of the item so that an alarm is generated when the valuable item moves out of range of the receiver. However, a disadvantage of this system is that it is restricted to protecting an item for which it is specifically designed.

According to the present invention, there is provided an alarm system comprising a master unit and a plurality of slave units, wherein the master unit comprises communication means for wireless communication with the slave units and the slave units each include means for wirelessly communicating with the master unit, and wherein the system further comprises a separation detector responsive to signals transmitted between the master unit and each slave unit to produce a separation signal when the transmitted signals are indicative of one or more of the slave units having become separated from the master unit and an alert generator coupled to the separation detector and arranged to generate an alert in response to the separation signal.

Preferably, each slave unit is arranged to transmit an identification signal of a predetermined amplitude, and the communication means of the master unit include the separation detector as well as an alarm indicator for generating an audible alarm in response to the separation signal. The separation signal may be generated when the received amplitude of a signal transmitted by a slave unit is less than a certain threshold value. In this way, subject to variations due to the shielding of both receiving and transmitting units, the orientation of their antennas, and other environmental factors, the separation signal is generated if one of the slave units moves or is moved more than a predetermined distance away from the master unit. When the separation signal is generated, an alert is activated to notify the owner of the protected items of the absence of one of the items.

An alert may also be activated at the out-of-range slave unit. Cancelling means may be incorporated in the master units and/or slave units to allow the user to deactivate an alert.

In the preferred system, both the master unit and the slave units are capable of two-way radio communication, communications between the master unit and the slave units being synchronised by a timing circuit in the master unit. Each member of the system, i.e. master unit and slave units may be given a respective identity within the system, the master unit having a storage device storing a register of system members or units, listed by their identity. Another register may contain different separation thresholds so that, according to the nature of and the needs of individual protected items, they may be assigned different respective thresholds. The setting of the thresholds may depend on the expected spacing from the master unit or owner during normal use. In this way, it is possible to build up a network of master and slave units in which the master unit polls the slave units in turn to ascertain their separation from the master unit in conjunction with their identities.

The system may have more than one master unit, one of the master units being assigned the role of primary master unit, and the or each other master unit constituting a secondary master unit. The primary master unit is arranged to be in two-way communication with the other master units as well as at least a majority of the slave units, and controls all communications within the system, including the timing of such communications. The master unit holds the network register and separation threshold register referred to above, and transmits the contents of these registers to the secondary master unit or units so that that may be reproduced in the latter.

Should the primary master unit become separated from a secondary master unit, or from any of the slave units assigned to it, the secondary unit takes over the role of primary master unit. In this way it is possible for the secondary master unit or units to act as a relay and a substitute should the primary master unit lose contact with one of the slave units.

The primary master unit may be arranged to receive communication signals from slave units not assigned to the system. It may then notify the user that a new slave unit is in range and allow the user to accept or reject the new unit. The primary master unit may then update the registers of the other master units. This allows for a flexible system in which valuable items can be added to or subtracted from the family depending on the user's requirements.

In the preferred embodiment of the invention the primary master unit is programmable to allow the user to change the allowable distances of different valuable items from the owner. In this type of operation the primary master unit will update the registers of all other master units. In a further aspect of the invention, if the primary master unit loses contact with the rest of the family, another master unit is assigned the role of primary master. This ensures that the system will still work if the primary master units gets misplaced or stolen.

In one embodiment of the invention, the system is designed for protection of personal valuables such as mobile telephones and laptop computers. With this application, the system may utilise a short-range, low-power radio communications standard such as Bluetooth (Registered Trade Mark) or a medium range standard such as the IEEE 802.11 standard. An alarm system in accordance with the invention may also be used to protect groups of persons and/or animals and use a cellular telephone network for communication and, optionally, GPS for position location, the separation detector including means for comparing position information from respective units to determine their separation.

Slave units in a short range system are intended to protect personal items such as wallets, mobile telephones and handbags, etc. The devices are miniature two-way radio communicators (e.g. credit card-sized or smaller) which are fastened to, or held inside the item to be protected.

Preferably, the slave units have no user controls other than an "operational" and "battery low" indicator. They respond only to request signals from a "qualified" master unit.

It is the master units which keep the family represented by the network connected together and which cause an alarm to be sounded if a slave unit is unreachable, i.e. it has become detached from the master unit without authority of the user. The controls on the master units preferably comprise an "on/off" control for powering-up or powering-down the unit, and an "accept new device" control, as well as a status indication. The master units may be designed to be attached, for instance, to a keyring, or clipped to the belt of a user, or they may be built into another electronic device such as a personal digital assistant (PDA) or a mobile telephone. Such a master may be designated by the user as the primary master. Having secondary masters allows continued protection for the slave units if the primary master is stolen, lost or becomes disabled, and also to raise an alarm in this instance.

As well as providing an audio or visual response, the alarm may be in the form of a telephone call to a pre-designated number.

The secondary master units listen to communications between the primary master unit and the slave unit in a passive mode, and communicate individually with the primary master unit. Updates to network membership caused by adding or removing slave units, or deactivating the network by the user, are sent to the secondary master unit by the primary master unit.

In normal operation of the system, the slave units are sequentially polled in a time sequence set by the number of devices consistent with providing a sufficiently early alarm in the case of separation, whilst maintaining reasonable power consumption for conserving battery life. If a slave unit is out of range from the primary master unit, it may transmit a signal causing one of the other master units to indicate if it has communication with the primary master unit. According to the response, the primary master unit decides whether to launch an alarm or not.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a general block diagram of a system in accordance with the invention; Figure 2 is a block diagram of a slave unit forming part of the system of figure 1; Figure 3 is a block diagram of a master unit forming part of the system of figure 1; Figure 4 is a flow diagram showing normal operation of a first master unit in the system; Figure 5 is a schematic diagram showing the timing of messages in the system Figure 6 is a flow diagram showing operation of the system for registration of a new device Referring to Figure I, an alarm system 10 in accordance with the invention consists of a "family" of units. The family contains a plurality of master units 11, 12, 13, one of which is assigned the role of primary master unit 11, and a plurality of slave units 14, 15, 16. The slave units 14, 15, 16 and secondary master units 12, 13 are in two-way communication with the primary master unit 11. The slave units 14, 15, 16 are in one-way communication with the secondary master units 12, 13 during normal use in that they transmit signals to the secondary master units 12, 13 but do not normally receive signals from the secondary master units 12, 13. The secondary master units 12, 13 passively receive the communications between the primary master unit 11 and the slave units 14, 15, 16 during normal operation. When a slave unit 14, 15, 16 is beyond the range of communication of the primary master unit 11 but within the range of communication of a secondary master unit 12, 13, the secondary master unit communicates with the primary master unit. The slave devices 14, 15, 16 are configured to be attached to or integrated into portable items such as keys, mobile phones, laptop computers or bags. At least the primary master unit 11 is kept with the owner of the protected items so that the owner may be alerted when the portable items are moved beyond a predetermined range from any of the master units l l, 12, 13. The alert may be an audio, visual or vibration alarm or alternatively, a particular telephone number may be dialled when the alarm is activated. The secondary master units 12, 13 may be placed in other locations within communication range of the primary master unit 11, e.g. in a vehicle or on another person, or they may be kept with a respective item in a group of items which are to be kept together. The units of family form a mobile, short range network with an individual identity. The communication protocol used is such that more than one family may exist in the same location without interference and unauthorized devices may not receive communications.

As shown in Figure 2, each slave unit 14, 15, 16 comprises an antenna 17 linked to a radio transceiver 18 which is linked to a microprocessor 19. The microprocessor 19 controls all of the transmissions of the slave unit. The slave unit only transmits to a master unit on receipt of a request signal from the master unit. Typically, transmission power is lmW, with a power consumption of lOmW. The transceiver 18 may be operate according to the Bluetooth (Registered Trade Mark) standard.

The microprocessor 19 is coupled to a display 20 and is programmed to cause the display to provide a status indication. The microprocessor 19 is also coupled to a simple control interface 21 for receiving User Activation and Power Up commands.

These commands for the slave unit may also be condoned remotely from a master unit 1 l, 12, 13. In addition, the microprocessor 19 regulates power usage of the slave unit through a power control block 22 which is linked to a battery 23 powering the unit. As an optional feature, the slave unit may include an alarm device 24 activated by the microprocessor 19 if the slave unit is sensed to be out of range of a master unit. There is also a clock 25 or timer linked to the microprocessor for signal timing.

Figure 3 is a block diagram of a master unit. The master unit has a number of functional components in common with the slave unit. Accordingly, the master unit comprises an antenna 26 linked to a Bluetooth (Registered Trade Mark) radio transceiver 27 which is linked to a microprocessor 28. The microprocessor 28 controls all communications of the master unit and includes a family register which stores information relating to the members of the family. The family register of each secondary master unit is updated regularly in accordance with information received from the primary master unit. The microprocessor 28 is programmed to activate an alarm device 29 if any of the slave units 14, 15, 16 is sensed to be out of range and may also be programmed to allow different ranges for individual slave units. The microprocessor controls the power consumption of the master unit by sending commands to a power control block 30 which is linked to a battery 31. There is also a clock 32 or timer linked to the microprocessor for signal timing. The master unit has a display device 33 for status indication and user controls 34, both of which are linked to l O the microprocessor 28. Functions provided by the user controls 34 include "on/off" and an "accept new devices" function for switching the master unit on and off and for altering the membership of the family.

The master units, operating under the control of their respective microprocessors 28, are programmed to control communication between members of the family and to activate an alert when any of the slave units 14, 15, 16 is sensed to have separated from a master unit 11, 12, 13. The separation between a slave unit and a master unit is estimated by detecting the amplitude of the received signal at the master unit.

Referring again to Figure 1, the role of primary master unit 11 is assigned to one of the master units 11,12,13. The primary master unit 11 controls the timing of signals and operation of the family. If the primary master unit 11 moves out of the range of communication of other members of the family, another master device is assigned the role of primary master unit. The primary master unit is also in control of the process allowing units to join or leave the family.

The sequence of the operations of the primary master unit in normal operation are now described with reference to Figures 4 and 5.

At the start of the communication cycle 35, the primary master 11 has status information relating to all units in the system as a result of the previous cycle. If a unit is sensed to be missing or outside a predetermined range (as determined, e.g., by signal strength), the primary master unit queries all other master units on the status of the missing unit 36. If the missing unit is not within the predetermined range of any of the other master units in the family the alarm process is activated 38.

If the primary master unit finds that all units are present, the primary master unit waits for the next active communication cycle 39 (the start of which is defined by a periodic pulse from the timer 32 (Figure 3) of the master unit) before starting to update information relating to the slave units in the family. A first one of the slave units is called 40, 51 and, as shown in Figure 5, on receipt of this request 71, this first slave unit transmits a reply signal to the primary master unit 72 and then returns to a sleep mode 73. The primary master unit waits for the reply 41 and then updates a status register with the new information 42, 43. The primary master unit repeats these status acquisition steps sequentially for the other slaves in the system 52, 53. When information relating to the last slave unit in the sequence 44, 53 has been obtained, the primary master unit updates the registers of the secondary master units 46. After this, there is a time period allocated for the primary master unit to receive transmissions from any new slave devices that are in range 55. When this process has been completed, the primary master unit is put into a sleep mode 56, typically for 5 seconds, until the cycle begins again. The timings of the communications and sleep periods are transmitted to all members of the family when they are admitted into the family.

Figure 6 shows the sequence of operations within the system for the addition of a new slave device in the family. For the new device to be registered within the family, it must firstly be powered up by the user 80. This causes the new device to transmit a signal to initiate connection to a nearby master unit 81. If no master unit response is received, the device waits for a defined time period 82 before repeating transmission of the connection signal. If the unit receives a response from a master unit, it sends an access code and device details to the master unit 83. The master unit then generates a request indication requiring the user to confirm that the device is to be added to the family 84. If the user confirms that the device is to be added to the family, the device is allocated the family identity and individual identity 85 within the family. This information is then added to the register of the master unit, and the registers of all other master units are updated 86. If the user does not confirm that the device is to be added to the family, the new device is instructed to terminate contact with the master unit 87.

Normal operation is then resumed.

Claims

1. An alarm system comprising a master unit and a plurality of slave units, wherein the master unit comprises communication means for wireless communication with the slave units and the slave units each include means for wirelessly communicating with the master unit, and wherein the system further comprises a separation detector responsive to signals transmitted between the master unit and each slave unit to produce a separation signal when the transmitted signals are indicative of one or more of the slave units having become separated from the master unit and an alert generator coupled to the separation detector and arranged to generate an alert in response to the separation signal.

2. A system according to claim 1, wherein each slave unit is arranged to transmit an identification signal of a predetermined amplitude, and wherein the communication means of the master unit includes the said separation detector, the master unit including an alarm indicator for generating an audible alarm in response to the separation signal.

3. A system according to claim 1 or claim 2, wherein the communication means of the master unit and the slave units are configured for two-way wireless communication between the master unit and the slave units.

4. A system according to claim 3, wherein the master unit and the slave units operate in synchronization as members of a network, each slave unit having a respective individual identity and being configured to transmit identification signals indicative of its identity, the master unit including a network register arranged to store the identities of the members of the network.

5. A system according to claim 3 or claim 4, wherein the master unit and the slave units includes respective clocks, and the said units are arranged such that the signals transmitted between the units causes synchronization of the clocks and synchronization of the transmitted signals.

6. A system according to any of claims 3 to S. wherein the master unit is configured to poll the slave units by transmission of interrogation signals to respective slave units in turn, and wherein each slave unit is configured to respond to the respective interrogation signal by transmitting a reply signal within a predetermined time period after the interrogation signal.

7. A system according to claim 4, wherein the master unit further comprises a separation information register for storing separation threshold information which determines the separation between a slave unit and the master unit that when exceeded causes generation of the separation signal.

8. A system according to claim 7, wherein the separation threshold information is representative of a received signal amplitude.

9. An alarm system according to any preceding claim, having a plurality of master units, one of the master units being a primary master unit which is in two-way communication with all other units in the system and controls all communications within the system and also controls the timing of communications within the system.

10. A system according to claim 9, wherein the master units are configured such that if the primary master unit loses contact with the slave units, a different master unit is assigned the role of primary master unit.

11. A system according to claim 4, wherein the master unit comprises a programmed data processor for controlling communications between the master unit and the slave units, the processor being configured to implement a network membership alteration process in that the master unit has notification means to notify the user of detection of a signal from a slave unit not included in the contents of the network register and confirmation means operable to allow the user to confirm that the said slave unit is to be included in the network register.

12. A system according to claim 11, comprising a plurality of master units, one of the master units being configured as a primary master unit and the other master unit or units each being configured as a secondary master unit, the primary master unit being configured to update the network register in each of the secondary master units in the system.

13. A system according to claim 7, wherein the master unit is configured such that separation threshold information may be different in respect of different slave units, the master unit including programming means allowing the stored separation information to be altered.

14. A system according to claim 13, having a plurality of master units comprising a primary master unit and at least one secondary master unit, wherein the primary master unit is configured to update the separation information register of the or each other master unit in the system.

15. A system according to any preceding claim, wherein separation detector is responsive to the amplitudes of the signals transmitted between the master unit in which it is contained and the slave units.

16. A system according to any preceding claim, wherein the communication means of the master unit or units and the slave units are arranged to operate according to the Bluetooth standard.

17. A system according to any of claims I to 15, wherein the communication means of the master unit or units and the slave units are arranged to operate according to the IEEE 802.11 standard.

18. A system according to any of claims I to 15, wherein the communication means of the master unit or units and the slave units are arranged to exchange signals via a cellular telephone network, the or each master unit and slave unit including respective position locating means, and wherein the separation detector is arranged to compare position information from the position locating means in respective units in order to determine their separation.

19. A system according to any preceding claim, wherein at least one of the slave units includes a satellite navigation receiver which is coupled to the communication means of the respective slave unit to apply position information to the signals transmitted by the slave unit to the master unit or units.

20. A system according to any preceding claim, wherein at least one unit of the system includes a cancelling means, allowing the user to deactivate an alert.

21. A method for generating alerts when physical elements of a group become separated from another element or elements of the group, wherein the method comprises: providing a master unit for attachment to or integrated in one element of the group; providing a plurality of slave units for attachment to or integrated in other elements of the group; transmitting a request signal from the master unit; on receipt of the request signal, transmitting a reply signal from one or more of the slave units, the master unit receiving the reply signal and from it producing an output signal indicative of the separation of the units; comparing a parameter of the output signal related to the separation of the master unit and a respective slave unit with a threshold value stored at the master unit; and generating an alert at the master unit and/or the respective slave unit if the parameter exceeds the threshold value.

22. A master unit for an alarm system as claimed in any of claims 1 to 20.

23. A slave unit for an alarm system as claimed in any of claims 1 to 20.

24. An alarm system constructed and arranged substantially as herein described and shown in the drawings.

25. A method for generating alerts when physical elements of a group become separated from another element or elements of the group, the method being substantially as herein described with reference to the drawings.