CA2596458C - Multiple conductor security tag - Google Patents

Multiple conductor security tag Download PDF

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Publication number
CA2596458C
CA2596458C CA2596458A CA2596458A CA2596458C CA 2596458 C CA2596458 C CA 2596458C CA 2596458 A CA2596458 A CA 2596458A CA 2596458 A CA2596458 A CA 2596458A CA 2596458 C CA2596458 C CA 2596458C
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CA
Canada
Prior art keywords
strap
module
insulated conductors
conductors
asset
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CA2596458A
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French (fr)
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CA2596458A1 (en
Inventor
Robert Donald Mcculloch
David G. Mcewing
Brian Wayne Martin
Jennifer Ann Hartfield Mckenzie
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
XMARK Corp
Original Assignee
XMARK CORP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US09/080,310 priority Critical
Priority to US09/080,310 priority patent/US5977877A/en
Application filed by XMARK CORP filed Critical XMARK CORP
Priority to CA 2271925 priority patent/CA2271925C/en
Publication of CA2596458A1 publication Critical patent/CA2596458A1/en
Application granted granted Critical
Publication of CA2596458C publication Critical patent/CA2596458C/en
Anticipated expiration legal-status Critical
Application status is Expired - Fee Related legal-status Critical

Links

Abstract

A security tag having a strap for securing the tag to an object to be protected-and an electronic module connected to the strap for detecting an attempt to defeat the tag by short circuiting and severing the strap. The strap is formed of plural discrete conductors connected to the electronic module, which conductors are insulated from each other at least along a substantial length of the strap. Short circuiting of opposite ends of a single pair of the conductors followed by severance of plural ones of the insulated conductors, or short circuit in between separate conductors can be detected by the electronic module as an alarm condition. Severance or misconnection of only one or a small number of the insulated conductors can be detected by the electronic module as not being an alarm condition.

Description

MULTIPLE CONDUCTOR SECURITY TAG
FIELD OF THE INVENTION
This invention relates to the field of.asset protection and personal security.,. and in particular to an.improved tag strap and,connector structure.

BACKGROUND TO THE INVENTtON The location of assets and of persons can be determined by transponders or active transmitters attached to respective assets and.persons. The transponder emits an identity signal which can be received by receivers located at various locations, such.
as adjacent doors,-in rooms, halls, ete:' The receivers typically report the received signals to a central computer which can draw a map'or update a database and thereby display'the locations of the assets and persons.
Assets which do not"report their locat3,on, or which-are identified to be at an unauthorized location,. can cause the central computer to set off.-an,alarm.. ..
The transponder is typically-attached to an asset or to a person by means-of a:strap which contains 20a conductor. Persons wishing to defeat the transponder.

will sometimes sever the strap to release the transponder from the asset and try-to make off with the asset. .However, severance of the strap.causesseverance of the-conductor, which can be. 'detected by the transponder, and which can transmit an alarm signal. A
person who understands that severance of the strap,will raise an alarm will sometimes short"circuit-the strap conductor, and then cut the strap, in order to defeat the severance detection circuitry of the.transponder.
In addition, sometimes wear and flexing of the strap will cause the conductor or the connection to the conductor to break, which will be interpreted by the severance detection circuitry of the transponder as an la attempted theft and therefore it will raise an alarm, even though there is no real threat of theft of the asset or location of a person in an unauthorized location..
In addition, in order to connect the conductor in the strap to the transponder, they must be carefully assembled in order to ensure that solid connections are made to the ends of the conductor. This has been found to be costly and clumsy.
SUMMARY OF THE INVENTION
-An embodiment of the present invention is a .strap which substantially reduces the likelihood that a broken conductor or intermittent contact in the strap will trigger an a].arm. Another embodiment of the invention is a connector which allows easy and inexpensive connection of the strap to a transponder, and in which connection tolerances and contact manufacturing tolerances are substant'ially relaxed from that of the above-described strap. Another embodiment of the 24-invention is a security tag which has substantially less ability to be defeated by short circuiting a conductor of the strap.
As a result, a less:expensive security tag can be made, with less likelihood of defeat by short circuiting, and with less likelihood of an alarm's being set off due to unintended severance of a conductor or misconnection of a contact of the strap on purpose or due to wear or flexing of the strap.
In accordance with an embodiment of the invention, a method of securing an object comprises fixing a band containing plural mutually insulated conductors to an object to be protected, in the event any of plural first predetermined numbers of opposite ends of the conductors are short circuited together via the conductors or by external means, making a determination that the band-is intact and not raising an 'alarm, and in the event of opposite ends of only a second predetermined number of pairs of conductors, or in the event no opposite ends of-any conductors are short circuited together by conductor or by external means, making a determination that the band has been tampered with, and raise an alarm.
In a.preferred form of the invention, the second predetermined number is equal to one.
In accordance with another embodiment, a security tag comprises a strap for securing the tag to an object to be protected and an electronic module connected to the strap for detecting an attempt to defeat the tag by short circuiting and severing the strap, the strap being formed of plural discrete conductors connected via terminals to the electronic module which conductors are insulated from each other -along at.least a substantial length of the strap, the.
module containing a*circuit for: in the event any of at least a predetermined number of plural opposite terminals to which the conductors are to be connected are short circuited together, making a'determination that the band is intact and do not raise the alarm; in the event only one pair or a small number of pairs of opposite terminals, or no opposite terminals, to which one or more conductors would be connected are short circuited together, making a determination of the band as having been tampered with, and rais.e an alarm.
In accordance with another embodiment, a security tag comprises a strap for securing the tag to an object to be protected and an electronic module connected to the strap for detecting an attempt to defeat the tag by short circuiting and severing the strap, the strap being formed of plural discrete conductors connected to the electronic module which conductors are.insulated from each other along at least a substantial length of the strap, wherein short = circuiting opposite- ends,of a single pair of the conductors followed by severance of plural ones of the insulated conductors, or short circuiting between various separate insulated conductors, can be detected by the electronic module as an alarm condition, and wherein only severance or.misconnection of only one or a small number of the insulated conductors is detected by the electronic module as not being an alarm condition.
In accordance with another embodiment, a connector.for a security tag having a multiconductor band, comprises a slot in an insulating body having dimensions slightly larger-than the cross-section of the band such as to guide insertion of the band into the slot,. and-conductive resilient mutually insulated contacts pointed toward'a rear end of the slot supported by the insulating body for piercing insulation surrounding said majority of conductors upon the strap.
once having been.inserted into the slot and past the contacts is pulled back outwardly relative to the slot, thereby making contact with said majority of conductors and at the same.time inhibiting the strap from being able to be pulled back out from the slot.
In accordance with another embodiment, apparatus for securing an object comprises a multiconductor security strap connected to a strap'tamper detector, wherein the conductors are mutually insulated over at least a major length of the strap, the strap being connected to the detector by at least one connector, the connector being comprised of a slot having dimensions slightly larger than the cross-section of the band such as to guide insertion of the band into the slot, and conductive resilient contacts pointed toward a rear end of the slot, for piercing.insulation surrounding said majority of conductors upon the strap once having been .inserted into the slot and past.the contacts is pulled outwardly relative to the slot, thereby making contact with said'majority of conductors and at the same time inhibiting the strap from be able. to_be pulled back out from the slot. The physical presence of a barrier at the end of the-slot can prevent,the strap from being pulled forward.
Another embodiment of the invention is an improvenlent in security of. attachment of the device to a tapered part of.the body (or structure), which reduces the chances of the device'falling*off or being kicked off a body part such as a baby's leg. In accordance with this embodiment, the strap attachment points to the module are offset from a center of the module wherein an axis of the strap is offset toward one edge of the module. The edge of'the module can thus be located over the narrowest part of the baby's leg, and the strap can be the shortest possible length; reducing the possibility of it being able to be slipped off the baby's leg.
It is preferred that the major length of the strap is its full length.
BRTEF DESCRTpTTON OF THE DRAWINGS
A better understanding of the invention will be obtained by a consideration of the detailed description below, in conjunction with the following drawings, in which:
Figure 1 is a schematic mechanical illustration of a tag in accordance with an embodiment-of the invention, Figure 2 is a schematic diagram of a circuit formed in accordance with an embodiment of the invention, Figure 3 is a schematic diagram of a circuit formed in accordance with another embodiment.of the invention, Figure 4 is a cross-sectional view of a preferred embodiment of a strap for use in a tag, Figure 5 is a schematic diagram of the connector, Figure 6 is a cross-sectional view of a preferred form of-a connector, .
Figures 7A, 7B and 7C are cross-sectional views of a-form of the connector in three stages of connection to the band, prior to insertion of the band, during insertion of.the band, and making contact to the conductors of the band, Figure 8 is a-perspective of the bottom of a.
baby's leg showing attachment of an embodiment of the security tag, and Figure 9 is another embodiment of the security tag shown in Figure B.
DETAT_LED DESCRIPTION OF EMBODIMENTS OF.TH INVENTION
Turning to Figure 1, a transponder is shown as an electronic module 1. A strap 2, which contains plural conductors connected to-the transponder, is wrapped around an.object such as the wrist or ankle of a person, an asset, or a protrusion of an asset. As noted earlier, the transponder sends out signals periodically or on an exception basis (i.e. when a change is detected) which identify the transponder (and thus the associated asset or person) and optionally a location if the transponder has picked up the location from a peripheral transmitter, and the receiver which has picked up the signal transmitted by the transponder can provide location information of the transponder to a central computer.
If the strap is tampered with, such as by cutting, or by cutting after an attempt to short circuit the strap, or by short circuiting between separate conductors the transponder should detect the tampering and transmit an alarm. In accordance with an embodiment of the invention, the strap is multi-conductor, each conductor being insulated from the next over a substantial length, preferably over its entire length.
Figure 2 illustrates a structure which can detect tamperinq, but which has the safeguard that more than one conductor must be severed before an alarm is raised. Further, more than one pair of,conductors must be short circuited together in order to defeat the system..
The conductors in the strap are 3A, 3B...3N.
The conductors are coupled to short circuit, open circuit and resistance detectors 4A, 4B...4N. Detectors 4A - 4N are coupled to logic 5. Both ends of each of the conductors are connected to detectors 4A - 4N.
Alternatively, one or more conductors may be deliberately left disconnected and an alarm raised if a connection is detected.
In operation, a small current is passed from the detectors 4A - 4N through the corresponding conductors 3A - 3N. If one of the conductors 3A - 3N is severed, this will be detected by the one of the detectors 4A -4N which is connected to the severed conductor, since current flow through that conductor will cease.
However, since current will continue to flow through the other conductors, the logic 5 can determine using a state machine that only one of the detectors 4A - 4N has detected a severed conductor. Since this can occur due to either a wire break caused by wear flexing or due to a corroded termination, no alarm is raised by logic 5.
However, if more.than one conductor has been severed, this is more likely due to a purposeful attempt to damage the band. In such case, more than one detector 4A - 4N will detect the cessation of the flow IS of current through the conductor connected to it, and the logic 5 in determining this state should raise the alarm.
it is possible that an attempt may be made to short circuit the ends of a conductor in order to maintain current flow through the condtictor. Such a short circuit is shown by wire 7. In the event the ends of one conductor e.g. 3A is short circuited, or the end of one conductor is connected to the other end of another, and then more than one other conductor 3B - 3N
is cut, the detectors coupled to those other conductors will detect cessation of current, and logic 5 will raise an alarm as described above.
Since the presence of the strap connected to the detectors 4A - 4N constitutes short circuits between the respective opposite terminals, the logic 5 should be implemented in either hard logic or by a microprocessor, to satisfy the process: in the event any of plural -opposite terminals to which the conductors are to be connected are short circuited together, make a determination that the band is intact and do not raise the alarm; in the event only one pair of opposite terminals, or no opposite terminals, to which one or, more conductors would be connected are short circuited together, make a determination that the band as having been tampered with, and raise an alarm.
It will be noted that during manufacture, if a connection of one conductor or a small number of conductors of the band are not properly made to a connector terminal and forms at least one open cirGuit, that will not cause an alarm to be raised since there will still be plural pairs of short circuits still in existence through plural remaining conductors of the band. The manufacturing tolerance in respect of connection of the band to the transponder circuitry, or the reliability of the.connector or connectors of the band to the transponder circuitry, can thus be significantly relaxed, decreasing the cost of the assembly.
It should be noted that the process usefully should be able to consider that the band has been tampered with, with any predetermined plural minimum number of conductors short circuited, for example 2, 3, etc, rather than only one. Also, the process usefully should be able to consider-that the band has not been tampered with, with any predetermined plural number of conductors remaining short circuited, for example 3, 4, etc, rather than only two.
In addition, or alternatively, in the event adjacent ends of more than one wire are short circuited together as.shown by wire 8, and then those and at least one other conductor are cut, consider that the band has been tampered with, and raise an alarm. The cessation of current in this case would be detected by more than one detector 4A - 4N, and an alarm raised by logic S.
The, conductors 3A - 3N can.each have a predetermined amount of resistance, and detection of-a reduction in the resistance caused by provision of a short circuit wire 7 by the corresponding detector, and the cessation of current in plural other conductors can cause an alarm to be raised by logic 5.
Figure 2'is an embodiment in which both ends -of each of the conductors are connected to a~corresponding detector. However, instead one of the ends of each of the conductors can be connected together and to a single return wire which is connected in common to each of the detectors.
Figure 3 illustrates the latter structure, but in this case each of the conductors contains resistance 9A - 9N. In addition in another embodiment as shown in this Figure the other ends of the conductors are connected to each other. Therefore each of the mutually connected ends of the conductors is connected to a single detector/logic circuit 11 through respective internal resistors 13A - 13N. The.detector/logic circuit detects the change-of resistance that occurs when ends of a pair of conductors are short circuited together via wire 8, or when the ends of a single conductor,are short circuited together via a wire 7, and.
raises an alarm.when the resistance is detected to change due to severing-of more than one conductor, due to short circuiting of one conductor.or of a pair.of conductors together. Alternatively or in addition, as noted earlier one or more conductors may deliberately be left disconnected and if connection is detected,_as may occur if tampering is in process, the logic can determine this state and.raise an alarm.
It is unlikely for a prospective tampering person to know which of _plural conductors'should be short circuited together in order to defeat the alarm system, or what.resistance is necessary in a defeating short circuit, or which conductors should be left disconnected. However, the manufacturer will know, and can use a multiconductor short circuit to defeat the, alarm system during testing.
An embodiment of the band is shown in cross-section in Figure 4. Plural separated flat conductors 17 are disposed in the same plane, and are coated with a flexible insulator 19.such as a plastic material. The insulator fills the space between the conductors and covers both sides, thus fixing them in space,insulated from each other.
The ends of the conductors 17 are connected to connector terminals 21., as shown'in Figure 5. It will be seen that five conductors are shown, but the connector has seven terminals. This invention allows a single conductor to be connected to more than one, te-rminal, and/or a connector with more than the number of conductors to accommodate bands-with various numbers of connector terminals which may be required for different applications, but will still not indicate an alarm due to some connector terminals not being connected to conductors, or one conductor being connected to more than one terminal, etc., due to the process described-above. The structure-can thus be, formed using a standard number of connector terminals for a variety of bands, thus reducing cost. "

The band can be connected permanently at one end to the transponder and have another end connectable to the transponder via a multiconductor connector, or both ends of the band can be connectable to the transponder via a pair of connectors. Figure 6 illustrates a novel form of connector which can be used at both ends or at only one end of the band. Reference is also made to Figures 7A, 7B and 7C which illustrate operation of the connector.
The connector is formed of an insulating enclosure which forms a slot 25. The slot can be either open at both ends (as shown), or can be closed at a back end to limit the distance that theend of the band can be inserted. The size of the slot is sufficient to accommodate and guide the end of the.strap.
A plurality of separate resilient barbs which are insulated.from each other extend into the slot, in,a backward pointed direction. Each of.the-barbs is connected to the transponder which is contained in the enclosure, i.e. preferably to the short circuit and open circuit detectors previously described.
As shown in Figure 7A, the barbs are not in contact.with the band, prior to insertion As the band is pushed into thd slot 25, it bends the barbs toward one side of-the slot, sliding past the barbs, as shown in Figure 7B. Once inserted, the band is pulled back outwar-dly. The barbs pierce the insulation 19, and as the band is pulled against the barb, the barbs are pushed into the conductors of the band, both making connection to the correspondingly located conductors and acting to lock the band in the slot, as shown in Figure.
7C. The band is thereby connected to the transponder.

In the event a person tampers with the band by attempting to pull the band out of the slot, this acts to both seat the band more securely in the slot and causes the barbs to.make better contact with the conductors. Tampering with the connector is this way is thus self-defeating.
A variation of the above constitutes a. preferred embodiment. In this case, the contacts are not barbs, but are resilient hard conductive contacts. Instead of the conductors being imbedded in an insulator as in Figure=4, they are printed on a flexible insulating base such as MylarTM. The conductors are covered with a thin insulating layer such as lacquer or vinyl which can be penetrated by abrasion.
In this case the.end of the band is pushed into the slot with the insulating layer facing the contacts.
The contacts abrade or otherwise penetrate the insulating lay_er over the conductors as the band passes the contacts. After insertion, the band is pulled outwardly. The friction against the contacts.causes them to substantially Ãully abrade the insulating layer under them and also forces the contacts against the band, causing the contacts to make good contact with the conductors. A difference between this embodiment and the one previously described-is that the contacts in this embodiment do not pierce the conductors.
It is also intended that in a further embodiment, the conductors can be printed on a substrate, and be pierced-using the barb form of contacts.
In either case, the band is trapped in the sl.ot by the contacts. In order to release the band, it can be cut, and pushed out the rear'of the slot in the inserting direction. The connector is then ready to receive and make-contact with a new band.
It will be recognized that the transponder module and strap are very usefully attached to persons, such as Alzheimer's patients, mental patients, prisoners; and newborn or older babies. On attachment to patients or prisoners, a system with which the transponders communicate can detect whether they have wandered off, and the"strap attachment to a transponder module.described herein will substantially foil their tampering in an,attempt to remove it. Similarly, attachment to babies can detect attempts at abduction, and the strap described herein will also substantially foil tampering by an abductor attempting to remove it.
Previously designed modules used for similar purpose have been either boxy, cubic, round or disk shaped, with the axis of the strap passing through the center of-the module so as to exert tension through-the center of the module, similar to a wrist watch.
However, we have found that this can allow the device to be slipped off the foot of a baby. The reason that the device can be slipped off is that a baby's leg is typically very tapered, and to accommodate the portion of the. module which is to either side of the axis of the -strap, the center of the module cannot be located at the narrowest diameter of the baby's.leg. Accordingly, the length of the strap must be greater than the periphery of the baby's leg at its narrowest part. This has resulted in the excessively long strap length to allow .30 the device to be slipped off if the edge of the module compresses the foot.of the baby.
In accordance with an embodiment of the invention, the shape of the module has one-edge with a very large radius. Indeed, the radius can be as large as infinity if desired (making the edge substantially linear). The strap is attached to the module so that one of its edges extends from.a location near or at the 5= large radius edge of the module. The connector or connectors described above is/are therefore located next to the large radius..edge of the module. One surface of the module which is next to the leg of the baby is preferably planar or slightly concave to accommodate the curvature of the baby's leg.
A perspective view of the module I attached to a baby's leg in accordance with this embodiment is shown in Figure S. As may be seen, the large radius edge 35 of the module is disposed next to the foot of the baby.
Since the strap extends around the narrowest part of the tapered leg of the.baby, its circumference is smaller than straps of the prior art, and this will greatly reduce the chances of the device falling or being-kicked _ off the baby.
Another embodiment is shown in Figure 9, in which the module 1 has an extension 33 to which the strap is connected or otherwise attached.,- The large radius edge 35 is at the bottom of the extension. The extension 33 can have the same, or a different thickness than the remainder of the module.
The latter two embodiments preÃerably use the multi-conductor form of strap and/or connector described earlier, or they it can be used independently.on modules using straps as in the pr'ior art.
A person understanding this invention may now-conceive of alternate embodiments and enhancements using the principles described'herein. All such embodiments and enhancements are considered to be within the spirit and scope of this invention as defined in the claims appended hereto.

Claims (9)

1. A security tag for an asset or person comprising a module and a strap, the module comprising a transponder, the strap configured to connect to strap attachment points on the module, said strap attachment points located at an edge of the module to facilitate a close-fitting configuration of the strap and module around a narrow periphery of the asset or person when the tag is secured to the asset or person and the edge of the module is located over the narrow periphery of the asset or person.
2. A security tag as defined in claim 1, in which the strap attachment points are located so as to position one edge of the strap along a line extending from approximately an edge of the module.
3. A security tag as defined in claim 1 or 2, including a strap having at least one elongated conductor embedded therein connected via the attachment points to a tamper detector within the module.
4. A security tag as defined in claim 3, including an electrical connector coupled to the tamper detector located at at least one attachment point.
5. A security tag as defined in any one of claims 1 to 4, the strap comprising a plurality of insulated conductors along substantially the entire length of the strap, said insulated conductors configured to connect to the module via one or more detectors, the module configured to detect an alarm condition and a non-alarm condition of the tag, said alarm condition characterized by a short-circuit between opposite ends of a single pair of the plurality of the insulated conductors followed by severance of more than a small number of the plurality of insulated conductors, or a short-circuit between more than a small number of the plurality of insulated conductors, and said non-alarm condition determined by severance or misconnection of zero, one or a small number of the plurality of insulated conductors, wherein both ends of each of the insulated conductors are connected to the same detector.
6. A security tag as defined in any one of claims 1 to 5, in which the shape of the electronic module has one edge of a substantially plane or slightly concave surface which has a large radius which extends between substantially opposite sides of said surface, the module having attachment points for the strap at locations adjacent opposite ends of said large radius edge.
7. A security tag as defined in any one of claims 1 to 6 in which the strap attachment points are located on opposite sides of an extension of the module, the extension of the module substantially smaller in a lateral dimension than the lateral width of the remainder of the module.
8. A security tag for an asset or person comprised of a module and a strap, the module comprising a transponder, the strap removably connected to the module, the shape of the module having a first surface, the first surface substantially planar or slightly concave and configured to conform to a corresponding surface of the asset or person, the module having a first edge characterized by an arc with a large radius, the module having attachment points for the strap at locations at opposite ends of said first edge to facilitate a close-fitting configuration of the strap and module around a narrow periphery of the asset or person when the tag is secured to the asset or person and the first edge of the module is located over the narrow periphery of the asset or person.
9. A security tag as defined in claim 8, the strap comprising a plurality of insulated conductors along substantially the entire length of the strap, said insulated conductors configured to connect to the module via one or more detectors, the module configured to detect an alarm condition and a non-alarm condition of the tag, said alarm condition determined by a short-circuit between opposite ends of a single pair of the plurality of insulated conductors followed by severance of more than a small number of the plurality of the insulated conductors, or a short-circuit between more than a small number of insulated conductors, and said non-alarm condition determined by severance or misconnection of zero, one or a small number of the insulated conductors, wherein both ends of each of the insulated conductors are connected to the same detector.
CA2596458A 1998-05-18 1999-05-14 Multiple conductor security tag Expired - Fee Related CA2596458C (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US09/080,310 1998-05-18
US09/080,310 US5977877A (en) 1998-05-18 1998-05-18 Multiple conductor security tag
CA 2271925 CA2271925C (en) 1998-05-18 1999-05-14 Multiple conductor security tag

Publications (2)

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CA2596458A1 CA2596458A1 (en) 1999-11-18
CA2596458C true CA2596458C (en) 2011-09-27

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CA2596458A Expired - Fee Related CA2596458C (en) 1998-05-18 1999-05-14 Multiple conductor security tag

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7064670B2 (en) * 2004-02-25 2006-06-20 Dmatek, Ltd. Method and apparatus for portable transmitting devices

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