GB2384648A

GB2384648A - Tagging system

Info

Publication number: GB2384648A
Application number: GB0201756A
Authority: GB
Inventors: Anthony Furness; Timothy Glyn Hankins
Original assignee: Intellident Ltd
Current assignee: Intellident Ltd
Priority date: 2002-01-25
Filing date: 2002-01-25
Publication date: 2003-07-30
Anticipated expiration: 2022-01-25
Also published as: WO2003063061A1; GB0201756D0; GB2384648B

Abstract

A tagging system and method includes at least one tag, preferably a plurality of tags, designed to provide a response signal upon receiving one or more identification codes associated with the tag and having a response range of less than 2 metres, or more preferably, 1 or 0.5 metres. The tag is preferably located on or in an article, and the range be less or substantially less than the size of the article. There may be a refractory period after the tag receives an incorrect identification code.

Description

TAGGING SYSTEM The present invention relates to a tagging system.

Radio frequency identification (RFID) data carrier devices (tags or transponders) are now being applied for security oriented applications such as property crime reduction and in combating supply chain shrinkage. Such developments are also being promoted by initiatives such as the Home Office Chipping of Goods Initiative. Typically, the tags carry identification codes that can be accessed without contact by radio frequency interrogation means. Unfortunately, conventional RFID data carriers are easy targets for a would-be criminal adversary intent on defeating or removing the means of identification. While tamper-evident tags are available and the embedding of tags can be seen to provide further levels of deterrence the act of interrogating a tag reveals its presence once the reader field is sufficiently within its vicinity.

The present invention seeks to provide an improved tagging system.

According to an aspect of the present invention, there is provided a tagging system including at least one tag designed to provide a response signal solely upon receipt of one or more identification codes associated with said tag and wherein the tag has a response range of less than two metres. Preferably, the response range is less than one metre and most preferably less than 0.5 metres.

According to another aspect of the present invention, there is provided a tagging system for use in identifying an article in which a tag is placed on or incorporated in the article, wherein the tag is designed to provide a response signal solely in response to one or more tag identification codes associated with the tag and wherein the response range of the tag is less than the size of the article.

According to another aspect of the present invention, there is provided a method of tagging an article including the step of providing a tag which is responsive only to one or more tag identification codes associated with the tag and which has a response range less than the size of the article; and locating said tag on or in the article.

Advantageously, the response range of the tag is substantially less than the size of the article, for example at least an order of magnitude less than the size of the article.

With the present invention, it is possible to provide a tagged article in which the presence of the tag and its identification can only be determined if the identification code of the tag is known as well as its location on the article. The system, therefore, can provide a secure method of identifying an article and in which, unless the identification of the tag

and its location are known, a third party may not detect the existence of the tag and therefore not have the ability to tamper with or remove the tag.

In the preferred embodiment, the tag is designed with a refractory period following the receipt of an incorrect code, in which the tag is set in an unresponsive state so as not to respond during said period even upon receipt of the correct identification code. This feature can substantially reduce the risk of the tag being betrayed by code scanning devices.

Advantageously, there may be provided a plurality of tags on or in any one article so that if one tag is located by an unauthorised person, there would still be at least one other tag hidden on or in the article for identification the article.

A tag can be configured to respond to more than one identification code, for example for different levels of authorisation, and may alternatively or additionally be configured to emit a different response code upon the receipt of an authorised identification code.

Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawing, in which the sole Figure is a schematic diagram of the main functioning elements of a preferred embodiment of tagging system.

The embodiment shown in the Figure provides a tagging system in which one or more tags are incorporated on or into an article to be protected such that the tag is not externally visible when looking at the article. The tag is of a type which requires the input of a specific identification code into the tag before the tag emits any response signal. Input is typically on the basis of a wireless communications link (for example radio frequency) with signals being sent from an interrogator.

Upon receiving the correct identification code, the tag responds to inform the interrogator of its presence. The response may be by the generation and transmission of a coded return signal, which may be same as the received code or a different code. As the tag will be specific to the article in which it is incorporated, identification of the tag will identify the article.

The tag has a short response range such that the interrogator must be placed close to the tag for the tag to respond. This may, for example, be a distance of two metres or less, although preferably the distance is one metre or less, most preferably 0.5 metres or less. Advantageously, the response distance of the tag is chosen so as to be substantially

less than the size of the article in which the tag is located. This difference may be, for example, an order of magnitude less than the size of the article.

Thus, a person or device operating an interrogator must know the location of the tag to place the interrogator close enough to the tag to prompt a response. For example, if the tag is incorporated within the structure of a boat, the interrogator must be placed at a location on the boat which is very close to the tag to cause the tag to respond.

An embodiment of structure of tagging system is shown in the Figure. Referring to this Figure, the embodiment of interrogator 10 shown has a facility to generate a radio frequency carrier field which carries as a modulated signal a user or automatically selected tag identification code. The interrogator 10 also includes a receiver section for detecting a coded response generated by the tag.

The interrogator 10 is able to generate or receive by way of a user input any one of a plurality, preferably a very large number, of possible tag identification codes for transmission in the carrier field.

The tag 20 is provided with a plurality of circuit units. The first is a field detection reset unit 22 designed to receive the code modulated signals from the interrogator. This unit 22 is coupled to an energy storage/rectification unit 24 and a synchronisation and a control unit 26, the structures of which will be apparent to the skilled person.

The field detection and reset unit 22 is designed to feed the received code to a code detection and extraction unit 28 which is operable to extract the code from the received carrier signal. The extracted code is then held in a holding register 30 for later comparison.

A code comparator 32 is coupled to receive the code held in the holding register 30 and designed to compare it with the tag's identification code held in another register 34.

The code comparator 32, that is the negative (no match) output thereof, is coupled to a trigger unit 36 which is operable to trigger a refractory period generator 38 upon the code comparator 32 issuing a no match output occurring when the received code held in the holding register 30 does not match the tag's own identification code. The refractory period inhibits functioning of the comparator 32 and may be a pre-set number of clock cycles or of variable duration.

The positive (match) output of the code comparator 32, that is the output indicative of a match between the received code and the tag's own identification code, is coupled to a response trigger 40 operable to generate a response code which is then modulated by

modulator unit 42 to create a code modulated return signal transmitted to the interrogator 10.

As explained above, the tag 20 is designed to have a short response range which may be two metres or less and is preferably less than 0.5 metres. Thus, the interrogator 10 must be placed close to the tag 20 for the tag to operate.

The tag 20 is designed to remain"quiet", that is"unresponsive"to anything other than the correctly coded modulated signal. It is also of a type which can be embedded or otherwise hidden within an item to be tagged.

Thus, in the presence of an interrogation field other than one containing the correct code of that tag, whether or not that interrogation field is coded or not, the tag remains silent and therefore does not betray its presence of the user or the interrogator. Thus, someone wishing to get a tag to respond and identify itself must know not only the identification code of the tag but also the tag's approximate location, in other words its approximate location within the article in which it is kept. This information can be provided in the form of a"passport"to the legitimate user or owner of the article.

The presence of the refractory period within the mechanism of the tag 20 is intended to deter the use of scanning techniques in which the coded field is sequentially changed in an attempt to find the valid code for that tag. Of course, the longer the period of inactivity set by the refractory timer, the lower is the risk of such a scanning technique identifying the correct code.

It is envisaged that for articles of a relatively large size or of high value a plurality tags could be incorporated into the device. The tags could be close to one another, in which case a user would need to be aware of the refractory period to generate the two or more codes with a suitable time gap between them to overcome the period of inactivity of the"second"tag to be interrogated. Alternatively, the tags can be placed sufficiently distant from one another that their interrogations are completely separate and do not generate a refractory period in the second tag to be interrogated.

It will be apparent that the response range for a tag need not be fixed but can be set in dependence upon the size of the article in which the tag is located. In this regard, in order to increase security, the response range of the tag is preferably smaller than the size of the article such that the user of an interrogator needs to do more than just place the interrogator close to the tag, that is he must know the location of the tag in order to be able

to place the interrogator close enough to generate a response from the tag. The system thus enables a person to authenticate the identity of the article and therefore the ownership thereof. This can be achieved in a manner in which a third party cannot simply swap tags for the reason of not knowing if any tags are fitted to the article, where they are located in the article and how many there may be. Security could be improved by incorporating one or more decoy devices in addition to readable tags.

The no-match response and the comparator 32 which is used to trigger a variable refractory period (that is a non-functional period over a variable of n cycles) to tag comparator may be synchronised to the pulse repetition frequency in the interrogation signal and based on random number generation. This may be a combination with a single or multiple match strategy for generating a valid response.

In some embodiments, additional features may be incorporated to enhance security against incidental or adversary scan attempts to detect the tag. These include, for example, the requirements of a correct code to be delivered several times within a particular time period in order to effect a response and for longer refractory periods to be introduced the more incorrect codes are presented. A full power down for a period of time could, for example, be required under such conditions in order to achieve a reset to the tag's original state.

Claims

1. A tagging system including at least one tag designed to provide a response signal solely upon receipt of one or more identification codes associated with said tag and wherein the tag has a response range of less than two metres.

2. A system according to claim 1, wherein the response range of the tag is less than one metre.

3. A system according to claim 1, wherein the response range of the tag is less than 0.5 metres.

4. A tagging system for use in identifying an article in which a tag is placed on or incorporated in the article, wherein the tag is designed to provide a response signal solely in response to one or more tag identification codes associated with the tag and wherein the response range of the tag is less than the size of the article.

5. A method of tagging an article including the step of providing a tag which is responsive only to one or more tag identification codes associated with the tag and which has a response range less than the size of the article; and locating said tag on or in the article.

6. A system or method according to any preceding claim, wherein the response range of the tag is substantially less than the size of the article.

7. A system or method according to any preceding claim, wherein the tag is designed with a refractory period following the receipt of an incorrect code.

8. A system or method according to any preceding claim, wherein the tag is configured to respond to more than one identification code.

8. A system or method according to any preceding claim, wherein there is provided a plurality of tags.