WO1999000769A1

WO1999000769A1 - Tag sensing

Info

Publication number: WO1999000769A1
Application number: PCT/AU1998/000491
Authority: WO
Inventors: Salahdin Yakoubi; Alf Johanssenon
Original assignee: Translink Systems Pty. Ltd.; Combitech Traffic Systems Ab
Priority date: 1997-06-25
Filing date: 1998-06-25
Publication date: 1999-01-07
Also published as: AUPO750897A0

Abstract

A tag (5) for use in a vehicle toll usage system is provided. The tag (5) has a circuit means (37, 39, 40, 41, 42 and 44) which has a flag circuit (42) which provides flag set signals (X, Y) which are useable for toll sensing when the tag (5) passes a toll point (7). The tag (5) is mounted relative to a tag mounting means (23) which is installed in a vehicle. The flag circuit (42) is set when the tag is in proximity to the tag mounting means (23) and removal of the tag (5) from the mounting means (23) sets the flag circuit (42) so that when the flag set conditions are obtained when the tag (5) passes the toll point (7), information on use such as fraudulent use of the tag can be determined. The tag (5) is used in a toll system and the system provides reports on the tag use. In one example the tag (5) has two flags, each being indepenently setable, and useable when set, to indicate removal of a tag (5) from proximity to the mounting means (23) and subsequent replacement in proximity to the mounting means (23), and use when not in proximity to the mounting means (23).

Description

TAG SENSING

FIELD OF THE INVENTION

This invention relates to tag sensing and relates particularly but not exclusively to tag sensing for use in detecting the passage of a vehicle past a toll collection point by an interactive process between a tag carried in a vehicle and a sensor at the toll collection point.

DESCRIPTION OF PRIOR ART

Toll collection systems for roadways have been in use for a considerable number of years. In some systems, it is necessary for a vehicle to stop to make a payment to an attendant at a toll collection point. More recently, automated means for toll collection have been provided where an authorised tag is provided in a vehicle and as the vehicle passes a sensor at a toll collection point, exchange of data from the tag to the sensor takes place whereupon an appropriate toll fee can be collected automatically by a debit system to the tag owner's account such as a bank account or some other credit account.

The tags can be considered as a form of cash because they can be used in an unauthorised manner. In some toll collection systems, a tag is permanently mounted to a vehicle. In that way, use can only be made when the actual vehicle passes a toll point. For fleet owners of vehicles, this can present some difficultly particularly when a vehicle is off road for service. In some instances, the fleet owner needs to rent a vehicle whilst the vehicle off road is being repaired. This, in turn, causes a problem with toll collection. In other systems, the tag can be freely moved from vehicle to vehicle and in such systems unauthorised use is common. In a private arrangement, a family may have two vehicles but only one tag. Thus, it is desirable to remove the tag from one vehicle so it can be used in the other vehicle.

OBJECTION AND STATEMENT OF THE INVENTION

Accordingly, in the systems known hitherto, problems have existed and the present invention attempts to address at least the aspect of determining tag usage. Particular embodiments permit determining when a tag has been removed and then used.

It should be appreciated that whilst the invention is to be described with particular reference to use in road toll collection systems in vehicles, the system is equally applicable to any other environment where monitoring the passage of objects past a control point is required. If some identification means unique to the object is provided to be carried with the object then the inventive concepts outlined herein will be equally applicable in that environment and the invention is to be interpreted broadly to embrace such use.

According to a first broad aspect of the present invention there may be provided a tag device having a casing, and a circuit means within the casing, said circuit means being for operatively coupling the tag with a tag detection sensor in a toll sensing system for toll accounting, said circuit means having a flag circuit which can be set or unset and wherein when set it will signal a set condition to said tag detection sensor and when unset it will signal an unset condition to said tag sensor, the set or unset conditions being useable in said toll sensing system for tag usage analysis .

Most preferably said flag circuit is set or unset by switch means in said circuit means . Most preferably said switch means is a logical multi-state device.

Most preferably said switch means is activated in response to said tag being located in proximity to switch activating means so that when in operational proximity said flag circuit will be either set or unset, and when not in operational proximity said flag circuit will be set oppositely to that when in said operational proximity.

Most preferably said switch activating means is carried by a tag mounting means which is fixed in a required position to an object such as a vehicle for tag detection by said toll sensing system so that when said tag is mounted said switch activating means will set or unset said flag circuit.

In one embodiment the said mounting means has a location sensor which will trigger the set or unset states when said tag is mounted to said mounting means. In another embodiment said mounting means may have a protruding member which can locate in an aperture in said casing of said tag.

It is particularly preferred that when said tag is mounted to said mounting means, removal of said tag from said mounting means requires activation of a releasing means useable for retaining said tag mounted to said mounting means.

According to a further aspect of the present invention there is provided a sensing system having tags carried by objects such as vehicles, which tags are sensed as objects pass a sensing point to account for such passing, said system having a facility to detect the removal of a tag from a required mounted position on an object and then use of said tag in said system, said tag having circuit means within a tag casing, said circuit means being for operatively coupling the tag with a tag detection sensor in a sensing system for accounting for such passing, said circuit means having a flag circuit which can be set or unset and wherein when set it will signal a set condition to said tag detection sensor and when unset it will signal an unset condition to said tag sensor, said flag circuit having a switch means activatable in response to said tag being in a required position on said object so said flag circuit is either set or unset, and wherein when said tag is sensed by said tag sensor at a sensing point the set or unset flag condition of said flag circuit will be sensed, said system having processing means to obtain signal information from said tag when said tag is sensed by said tag sensor, said signal information including object or owner identification, and flag set or unset signal information, and to permit analysis of the signal information against past use signal information for the tag object or owner to determine the removal of a tag from a required mounting position and then use of said tag in said system.

Most preferably said analysis enables a report to be provided which can be used to assess possible unauthorised tag use.

Such system has the advantage if used in a road toll sensing system that all tag use can result in toll collection.

BRIEF DESCRIPTION OF DRAWINGS

In order that the invention can be more clearly ascertained an example of a preferred embodiment for use in a road toll collection system will now be described with reference to the accompanying drawings wherein:

Figure 1 is an overview schematic diagram of typical electronic tolling and traffic management system architecture .

Figure 2(a) is a side view, in transverse cross- section, of one example a typical tag and a mounting means;

Figure 2(b) is similar to Figure 2(a) but of a different example.

Figure 3 is a block schematic diagram of the electronic components of the tag shown in Figures 2(a) and 2 (b) ;

Figure 4 is a block schematic diagram of part of the functionality of the electronic tolling and traffic management system; Figure 5 is a graph showing usage under one set of circumstances; and

Figure 6 is a graph showing use under a different set of circumstances to that in Figure 5.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to Figure 1 there is shown an electronics tolling traffic management system architecture overview diagram. Here, there is provided a system 1 which can be divided into a number of unique modules. The first module comprises customer's vehicles 3. Each customer's vehicle 3 contains a particular tag 5 which is suitably mounted in the vehicle at a position which will enable ready detection as a vehicle passes a toll point. The techniques for such detection are considered known in road toll collection systems.

The tags contain an electric circuit means (not shown in Figure 1) which has unique signal information provided in the tag concerning the owner of the tag. This signal information can be provided to permit identification of the owner and the subsequent debiting of an appropriate account, such as a bank account, for toll usage and is considered known in this art . The electronic circuit also includes a flag setting circuit to be referred to hereinafter and this represents an improvement over the known art .

The next part of the system comprises the toll collection points 7 which have roadside equipment sensors 9 which extract the signal information from the tag as a vehicle passes the tolling point 7. In this example, the tag 5 circuitry is activated as it comes into proximity of the sensors 9 and is put into a transmitting mode to transmit information to the sensors 9. That signal information is then transmitted to an operation centre 11 for processing. Typically, the connection between the tolling point 7 and the operation centre 11 is via a wide area telecommunications network 13 such as a PTSN. Other forms of connection such as radio connection, land line and the like are possible.

The operation centre 11 contains a central toll computer 15 dedicated solely to toll collection. This computer may have the facility to dial a bank for accessing funds of the owner of the tag 5. It may also have access to a credit facility retained at the central toll computer

15 itself and automatically debit any credit available for the owner of the tag. The operations centre 11 has a second computer comprising central control computer 16 which may, in fact, be a single computer forming pact of the central toll computer 15. The central control computer

16 is provided for analysing whether the tag 5 has been removed from mounting within the vehicle and to perform other control functions of the system. Reports can be generated from the central control computer 15 which can be analysed to determine authorised use of the tag. Such reports can be provided to the owner of the tag 5. These reports are obtained by analysing the flag setting conditions of the flag circuit of a tag 5 as it passes the tolling point 7 against past use signal information obtained from the tag 5.

The system 1 also includes, a traffic management system 17 which has automatic incident detection 19 such as video cameras or the like to determine accidents or traffic flow conditions, traffic sensors, and signs 21 which can be activated either automatically under control of the central control computer 15 or by operator intervention.

Referring now to Figures 2(a) and 2(b) there are shown respective transverse cross sectional views of two embodiments of typical tags 5 and mounting means 23 therefor. The sensor 5 has a plastics material casing 25 which encapsulates an electric circuit means 27. The circuit means 27 can be powered by suitable batteries or by other suitable means . The circuit means 27 includes known circuitry for providing identification data about the owner of the tag to the sensors 9 and to the system 1 by activating a transmitter (not shown) in the electric circuit means 27 to transmit that information to the sensor 9. This information can be embedded within the circuit means 27 as a tag is a assigned to a particular owner. The circuit means also includes a feature of a flag circuit (not shown in Figure 2(a)) which will be described hereinafter. The identification data, of the flag set conditions of the flag circuits are derived collectively from signal information which is received by sensors 9 at the tolling points 7.

The flag set conditions may be initiated by one of several methods of switch activation. In one embodiment shown in Figure 2(a) the mounting means 23 has a non- intrusive location sensor 46 that may cause initiation of switch means (not shown) via a non-contacting device in the mounting means 23. Typical non-contacting devices may be any proximity sensing device, for example inductive, capacitive or magnetic coupling. This will be sensed when the mounting means 23 is attached to the casing 5 and operates or sets a flag circuit as will be described hereinafter.

In the other embodiment shown in Figure 2(b) which is electrically similar to that in Figure 2(a), the tag 5 has an aperture 29 for receipt of a protruding member 31 forming part of the mounting means 23. Insertion of the protruding member 31 into the aperture 29 activates a switch means (not shown) which, in turn, operates the flag circuit as will be described hereinafter. The switch means may be activated in many ways such as by a mechanical switch which is closed or opened on insertion of the protruding member 31 or by optical sensing of the insertion of the protruding member 31 or by some proximity sensing of the protruding member 31. In one variation, a reed relay switch may be activated by operation of a magnetic coupling between the protruding member 31. In this case, a permanent magnet may be provided as part of the protruding member 31.

The mounting means 23 is typically mounted to a vehicles windscreen by an adhesive medium 33 carried on the rear of the mounting means 23. Specifications may be provided for the correct position of mounting of the mounting means 23.

The mounting means 23 includes a releasing means 35 which co-operates with the aperture 29 so that the tag 5 can only be removed from the mounting means 23 by activation of the releasing means 35. In the embodiment of Figure 2(b), the releasing means 35 comprises an upstanding rib on the protruding member 31. This rib, in turn, engages in a corresponding recess within the aperture 29. Removal of the tag 5 from the mounting means 23 requires either a manual force to be applied to the tag 5 so as to cause the releasing means 35 to permit releasing and subsequent removal of the tag 5 from the mounting means 23 or use of a tool such as a screw driver to lever the rib from the recess. Thus, if the tag 5 is removed from the mounting means 23, the switch means 9 will operate the flag circuit 37 to provide a set condition in the flag circuit 37 which will represent that the tag has been removed and therefore that the tag is possibly no longer in a vehicle to which it is notionally assigned by the owner of the tag 5. A similar function exists with the proximity sensors 46 shown in Figure 2(a).

Referring now to Figure 3 there is shown a block schematic diagram of the electric circuitry of the circuit means 27 of each tag 5. Here, the electronic circuit 27 is basically a known circuit but has an improvement of a flag set circuit 37 and a switch 39 which is activated by attaching the mounting means 23 to the tag 5. Thus, the circuit 27 can be provided with information relating to the tag owner in a data section 41. The flag set circuit 37 has two output data signals derived from the switch 39 activation. These will provide the following status information: -

1. Status Bit X - Tamper - Set to a "1" if the read status indicates that the tag has been tampered with ie. the tag 5 has been removed from and replaced on the mounting means 23.

2. Status Bit Y - Tag not in support - Set to "1" if the tag 5 is sensed when not mounted to the mounting means 23.

All the signal information from the data section

41 and from the flag set circuit 37 are combined as signal information which is read as the tag 5, in a vehicle, passes the sensors 9.

It can therefor be seen by varying Figure 3 that a status information transmitter 40 receives data signals representing three types of data:

1. Tag owner data .

2. Status Bit X - Tamper . 3. Status Bit Y - Tag not in support.

The status bit X and the status bit Y are provided from a decode logic circuit 42 which is connected with the flag set circuit 37 to decode the switch status change signals from switch 39.

Accordingly, when a tag comes in proximity to a sensor 9 at a toll station 7, the transmitter 40 within the tag will be activated to, in turn, transmit the status information of the tag owner data, the status bit X and the status bit Y. That will then be received by the sensors 9 and the central control computer 16 will appropriately decode it and utilise it for analysis of the tag usage. The circuitry in the tag 5 is provided with continuous power from a power supply 44 so that the decode logic 42 can sense removal of the tag and appropriately provide the status bit X or status bit Y signals. The receiver 44 is shown with an output connecting to the status information transmitter 40 and also to the decode logic 42. The receiver 44 is therefore used to switch on the transmitter 40 when the tag 5 is in proximity to the sensor 9. The connection with the decode logic 42 is to take into account resetting of the decode logic if the tag has been removed from its mounting means 23 and then reinserted on a mounting means 23 and then passed past a sensor 9. In this condition, the received signals processed by the sensor 9 and determined by the central control computer 16 determine that the tag 5 has been removed from its mounting means ie. the status bit X is ON and the status bit Y shows that it is set to OFF meaning that the tag has been reinserted on a mounting means 23. When this condition is sensed, a transmitter at the sensor 9 then transmits a signal which is received by the receiver 44 and passes to the decode logic 42 to immediately switch to OFF the status bit X flag.

Referring now to Figure 4 there is shown a block schematic overview diagram of part of the processing performed by the system 1. Here, signal information from a tag 5 is collected by sensors 9 at the toll point 7. That information is then processed by the operation centre 11 to obtain the tag owner data in a collect tag signal information processor 50 to, in turn, collect a toll for the passing of the tag 5 past the tolling point 7 at a toll collect module 52. The signal information is further processed to extract information concerning the flag set/unset condition of both status bit X and status bit Y by module 54. The flag set condition can be triggered either by a flag signal being ON or a flag signal not being present ie OFF. In some other instances, a flag set condition may be signalled by a particular combination of signals, and a flag unset condition may be signalled by a different particular set of signals. The exact form of how the flag set conditions are signalled can be chosen by a suitable electronics and/or toll collection engineer. The important aspect, however, is that a flag set or flag unset condition can be determined from the signal information.

The flag set or unset condition is then analysed at module 56 against past usage data for the same tag 5 and a report is provided. The report can be provided to a supervisor person at the operation centre 11 for analysis before a decision is made to provide the report to the owner of the tag 5 or alternatively, a report may be generated automatically to the owner of the tag. This report may be at periodic intervals such as weekly or monthly or may be initiated upon request by an owner of the tag. It may also be initiated automatically if the system determines that a tag has been removed from the mounting means 23. The exact instances of when a report will be provided to an owner can be decided by system administrators and/or public use requirements. Information concerning the tags usage is stored in store 58.

If the analysis module 56 determines that the tag has been removed from its mounting means 23 and then remounted, it will initiate a transmission via transmitter 60 to transmit a signal back to the tag to set the X flag to OFF thereby setting it correctly for being mounted in mounting means 23. This sensing, however, tells the operation centre 11 that the tag has been removed from its mounting means 23 and re-mounted. This can then be used to provide a report to the owner of the tag of that removal so, if considered necessary by the owner of the tag, an investigation into use of the tag can be made.

Referring now to Figure 5 there is shown a particular form of operation of a further flag which may indicate acceptable use of the tag 5. Here, there is a first flag set condition identified by 43, a subsequent flag reset identified by 45 and three toll uses. In this condition, on tag removal, a flag is either set or unset at 43 signifying removal from the mounting means 23. At 45, a flag is oppositely set to that when it was removed at 43. This can all be determined via software in the operation centre 11 which analyses the X and Y flag set states.

Referring now to Figure 6 there is shown a view similar to that of Figure 5 but here the use may be unacceptable use. Here it shows, at 43, the setting or unsetting of a flag upon removal of the tag 5 from the mounting means 23. Again, this can be determined via software in the operation centre 11 from the X and Y flag set states. It then shows three toll usages whilst the flag is set in this condition. hen the tag 5 is replaced to the mounting means 23 as at 45, the flag is again set oppositely to that when it was removed at 43. The system then detects further toll use while in the replaced condition. Clearly, in this environment, the tag has been removed and used whilst in a removed condition without being replaced. This may, in fact, be authorised use of the tag or it may not. For example, if the tag is transferred from one vehicle to another with approval or knowledge of the owner of the tag, then this would be correct and authorised use. If however, the tag was taken from one vehicle and used in another vehicle such that it is not with the approval or knowledge of the owner of the tag then the owner of the tag 5 should be made aware of the particular usage. Thus, a report can be provided which can be analysed to determine if the use is authorised or not . For example, signal information may be recorded by the operations centre 11 concerning the date and time of each toll use. Thus, by noting the particular flag setting conditions when the use occurs, it is possible to review the report and determine if the use of the tag has been authorised. A physical/logical explanation of operation is set out below and outlines what is happening with the flag setting conditions.

Two logical flags are shown in Table 1. The "Logical flag - Tamper X" in column two is used to indicate whether the tag 5 has been separated from, then re-attached to the support bracket 23.

It is noted that the last transaction in column two shows that the flag is switched ON but is immediately turned OFF on sensing. This occurs by way of a duplex transmission/reception function from the sensors 9 when a tag 5 is in proximity, in being able to transmit information to the tag 5 from transmitter 60 which can then be processed within the tag 5 in the receiver 44 and decode logic 42 to change the state of the X flag. The system, therefore immediately recognises that the tag has been refixed and sets the tag to the original condition. It should be noted that in this explanation, the flag is shown as being OFF when the tag is fixed. The opposite condition should be considered as an alternative and not outside the scope of the present invention.

The "Logical (Flag) Tag in Support Y" in column three indicates immediately (OFF) the tag is attached to the support bracket 23. The flag changes to the (ON) state immediately the tag 5 is removed from the support bracket 23.

The flag state cannot be reset by any means other than attaching to or removing the tag 5 from the support bracket 23. The opposite condition should be considered as an alternative and not outside the scope of the present invention.

A further explanation of the logical relationship of the tag to the mounting means and the flag sensing and report sensing is set out below.

• (-) : No Transaction occurred.

• Tamper alarm as shown in column three is immediately turned OFF when:

- Tamper Flag (X) is OFF, and

- Alarm ON as shown in column three is reported successfully to the Roadside System.

• Conciliation of transactions 2,3 and 4 shows the Tag used unattached and potentially changed vehicle.

• Conciliation of transactions 5,6 and 7 shows the Tag potentially changed vehicle but Tag not used unattached.

The "Logical (Flag) - Tag in Support (Y)" in column four indicates immediately the mounting status of the Tag in relation to the support bracket 23.

As the flag state (Y) cannot be reset by any other means than attaching to, or removing the tag 5 from the support bracket 23, this simplifies the decoding logic required in the controller 11. It should be noted that transactions 4 and 6 show similar functions to the last transaction in the previous explanation where the flag (X) is ON and immediately switched OFF by the duplex function from the sensors 9 as the tag passes a tolling point at transaction 7.

The flags (X & Y) and flag circuits can be considered as digital markers which provide internal Boolean parameters dependent on both the mounting history and current mounting status of the tag 5. The "Tamper Flag (X)" in column three, is set to

ON when the tag 5 is separated from support bracket 23 and this will cause an alarm state when interrogated by the toll sensor and relayed to the central toll computer 15. The "Tamper Flag (X)" is immediately set to OFF when the alarm has been successfully transmitted to the equipment installed on a Gantry at the tolling point 7 provided the tag 5 has been re-attached to a support bracket 23.

The "Tag in Support Flag (Y)" in column four indicates immediately the mounting status of the tag in relation to the support bracket 23.

As the flag state (Y) cannot be reset by any other means than attaching to, or removing the tag 5 from the support bracket 23, this simplifies the decoding logic required in the controller 11. Automatic remote monitoring of a correct or authorised tag installation is then provided by the analysis of the alarm status, ie. ON or OFF, in the tag consecutive transaction data received by the central toll computer 15. Modifications may be made to the invention as would be apparent to persons skilled in the electronics and/or toll collection arts.

These and other modifications may be made without departing from the ambit of the invention the nature of which is to be determined from the aforegoing description.

Claims

1. A tag device having a casing, and a circuit means within the casing, said circuit means being for operatively coupling the tag with a tag detection sensor in a toll sensing system for toll accounting, said circuit means having a flag circuit which can be set or unset and wherein when set it will signal a set condition to said tag detection sensor and when unset it will signal an unset condition to said tag sensor, the set or unset conditions being useable in said toll sensing system for tag usage analysis.

2. A device as claimed in claim 1 wherein said flag circuit is set or unset by switch means in said circuit means .

3. A device as claimed in claim 2 wherein said switch means is activated in response to said tag being located in proximity to switch activating means so that when in operational proximity said flag circuit will be either set or unset, and when not in operational proximity said flag circuit will be set oppositely to that when in said operational proximity.

4. A device as claimed in claim 3 wherein said switch activating means is carried by a tag mounting means which is fixed in a required position to an object such as a vehicle for tag detection by said toll sensing system so that when said tag is mounted said switch activating means will set or unset said flag circuit.

5. A device as claimed in claim 4 wherein said mounting means has a locating sensor which will trigger the set or unset states when said tag is mounted to said mounting means.

6. A device as claimed in claim 4 wherein said mounting means has a protruding member which can locate in an aperture in said casing of said tag.

7. A device as claimed in claim 6 wherein when said tag is mounted to said mounting means, removal of said tag from said mounting means requires activation of a releasing means useable for retaining said tag mounted to said mounting means.

8. A device as claimed in claim 2 wherein said switch means is a logical state device.

9. A device as claimed in claim 3 wherein said flag circuit has two flag circuits, one being for flag set conditions when the tag is in proximity to or is not in proximity to said switch activating means and the other being for flag set conditions which signify the tag has been removed from proximity to said switch activating means and has been replaced in proximity to said switch activating means, and wherein each flag set circuit provides flag set conditions which can be sensed independently for providing information on tag usage.

10. A sensing system having tags carried by objects such as vehicles, which tags are sensed as objects pass a sensing point to account for such passing, said system having a facility to detect the removal of a tag from a required mounted position on an object and then use of said tag in said system, said tag having circuit means within a tag casing, said circuit means being for operatively coupling the tag with a tag detection sensor in a sensing system for accounting for such passing, said circuit means having a flag circuit which can be set or unset and wherein when set it will signal a set condition to said tag detection sensor and when unset it will signal an unset condition to said tag sensor, said flag circuit having a switch means activatable in response to said tag being in a required position on said object so said flag circuit is either set or unset, and wherein when said tag is sensed by said tag sensor at a sensing point the set or unset flag condition of said flag circuit will be sensed, said system having processing means to obtain signal information from said tag when said tag is sensed by said tag sensor, said signal information including object or owner identification, and flag set or unset signal information, and to permit analysis of the signal information against past use signal information for the tag object or owner to determine the removal of a tag from a required mounting position and then use of said tag in said system.

11. A system as claimed in claim 10 wherein said analysis enables a report to be provided which can be used to assess possible unauthorised tag use.

12. A system as claimed in claim 10 used in a road toll sensing system, and wherein all tags sensed at the sensing point by said tag sensor result in toll collection.

13. A system as claimed in claim 9 wherein said flag circuit is set or unset by switch means in said circuit means .

14. A system as claimed in claim 13 wherein said switch means is activated in response to said tag being located in proximity to switch activating means so that when in operational proximity said flag circuit will be either set or unset, and when not in operational proximity said flag circuit will be set oppositely to that when in said operational proximity.

15. A system as claimed in claim 14 wherein said switch activating means is carried by a tag mounting means which is fixed in a required position to an object such as a vehicle for tag detection by said toll sensing system so that when said tag is mounted said switch activating means will set or unset said flag circuit.

16. A system as claimed in claim 15 wherein said mounting means has a locating sensor which will trigger the set or unset states when said tag is mounted to said mounting means.

17. A system as claimed in claim 15 wherein said mounting means has a protruding member which can locate in an aperture in said casing of said tag.

18. A system as claimed in claim 14 wherein said flag circuit has two flag circuits one being for flag set conditions when the tag is in proximity to or is not in proximity to said switch activating means and the other being for flag set conditions which signify the tag has been removed from proximity to said switch activating means and has been replaced in proximity to said switch activating means, and wherein each flag set circuit provides flag set conditions which can be sensed independently for providing information on tag usage.

19. A system as claimed in claim 18 wherein said sensing point includes a transmitter to transmit a signal to change the set state of said one flag circuit of said flag circuit in response to indicating flag set conditions by said flag set circuit that indicate removal of said tag from proximity to said switch activating means and subsequent replacement in proximity to said activating means .