1 2442778 Portable Security System This invention relates to a portable
security system for preventing two or more objects from being separated more than a specified distance. In particular, but not exclusively, the invention relates to a portable security system for preventing the objects chosen by a user, for example, electronic devices or a child, from being separated from that user more than a specified distance.
Many problems are created by the theft of wallets, purses, car keys, mobile phones and other valuable possessions. As well as the immediate theft there can be further problems created by identity theft using information included in the possessions that have been stolen. Even more distressingly, straying children or pets can find themselves in trouble, such as dangerous traffic, or may even become vulnerable to abduction.
There are existing products to monitor theft and detectors and locators for tracking down lost or straying items. However, these suffer from one or all of the following disadvantages: they are not portable; they do not monitor the loss of an object but need to be manually initiated to find the lost object; or they are vulnerable to interference from environmental factors. It is known for example to provide a detector using a single radio frequency to detect and/or locate the position of an object. The radio frequency used by the detector may be interfered with by the large amount of electromagnetic radiation that exists in the modern world. This may either prevent a signal from being detected, and hence cause a false alarm, or create the impression of a signal being received when the object has been taken and thus its absence remaining undetected. The * 2 interference may be from, among other things, mobile telephones, Bluetooth communication devices, WIFI networks, or RF goods tagging systems used in retail.
The present invention seeks to mitigate or overcome one or more of the above-identified disadvantages associated
with the prior art.
The present invention provides portable security apparatus comprising a master transponder and a secondary transponder, wherein each transponder is associated with an alarm, the transponders being arranged to transmit and receive two signals of different frequency back and forth between each other, characteristics of the signals providing information dependent on the distance between the master transponder and the secondary transponder, and the apparatus is further arranged to monitor the signals such that, in use, should the distance between the master transponder and the secondary transponder exceed a specified distance then at least one of the alarms is activated.
The master transponder and secondary transponder may comprise Radio Frequency Identification (RFID) tags.
Advantageously, the master transponder and secondary transponder form a set, where the two transponders are matched to each other both to send and receive the two signals of different frequencies. Advantageously, the use of two signals of different frequency reduces the problem of interference from other radio frequency signals in the environment. The security apparatus may be arranged such that both signals have to be received to counter the problem of false signals indicating the presence of an object, or that only one signal need be received, thus preventing false * 3 alarms when one of the signals is prevented from being received. The choice between the two options relating to how the signals have to be received may be made during the manufacture of the security apparatus and depends on the operational parameters required for the apparatus.
The two signals of different frequency may include predetermined codes, the codes transmitted and recognised by both the master transponder and secondary transponder. The codes transmitted via the two signals of different frequency may be selected randomly from a range of codes during the manufacture of the apparatus and set permanently for the lifetime of the apparatus (meaning in this case, in a manner which is not readily changeable by the user of the system and allowing two or more sets to operate within close proximity to each other without one interfering with the other). The two signals of different frequency may be selected randomly from a range of frequencies during manufacture of the apparatus and set permanently for the lifetime of the apparatus. Preferably, the at least two frequencies lie in a range between 30kHz and 5.8GHZ.
The master transponder may include an antenna and two radio frequency circuits arranged such that, in use, the two radio frequency circuits operate sequentially, sharing the antenna and transmitting and receiving to and from the secondary transponder. The secondary transponder may include an antenna and two radio frequency circuits arranged such that, in use, the two radio frequency circuits operate sequentially, sharing the antenna and transmitting and receiving to and from the master transponder. Sharing an antenna between two radio frequency circuits may reduce both the cost and weight of the transponder. * 4
The master transponder may include a reset switch to deactivate any alarms associated with the secondary transponder, provided the secondary transponder associated with the alarm is within the specified distance from the master transponder. The master transponder may include a reset switch to silence any alarm associated with the master transponder that has been activated. The master transponder may include an on/off switch to enable it to be turned on and off. Advantageously when the off switch is pressed the master transponder sends out a "close down" signal to the or each secondary transponder causing it to enter a sleep mode in which it consumes very little power.
The specified distance may be selected during the manufacture of the security apparatus and permanently set for the lifetime of the apparatus. The sets of master transponder and secondary transponder are preferably manufactured such that the specified distance and the frequencies are preset during manufacture. This has the advantage of being cheaper than making the members of the set with adjustable frequencies, may save weight over having an adjustable set of transponders and significantly increases the ease of use of the security apparatus.
Furthermore, once the set has been manufactured, there is no easy way of identifying what frequencies that set operates on, increasing the security of its operation There may be a plurality of secondary transponders, each secondary transponder being associated with an alarm.
Advantageously, this means that the security apparatus comprises a set including a plurality of secondary transponders and can be used to protect a plurality of objects with only one master transponder. Preferably, each of the plurality of secondary transponders transmits a * 5 unique, with regard to the other members of the set, identification code to enable the master transponder to identify it. Advantageously, the master transponder may be arranged to transmit and receive two signals of different S frequency to and from the plurality of secondary transponders, and the apparatus being further arranged to monitor the signals such that, in use, should an indication of the distance between the master transponder and any of the secondary transponders exceed a specified distance then at least one of the alarms is activated. Preferably, the specified distance is the same for each member of the set.
This allows the set to be defined by the number of secondary transponders and the specified distance that the master transponder and the secondary transponders are allowed to be separated. The master transponder may transmit and receive signals to and from each of the plurality of secondary transponders sequentially, moving from one to the next in a predetermined order. Alternatively, the master transponder may transmit and receive signals to and from each of the plurality of secondary transponders simultaneously.
A user may purchase a set in accordance with their needs as regards the number of secondary transponders required and the specified distance they wish them to be able to be separated from the master transponder. This greatly simplifies the choices available to the user, and improves ease of use, as no set up steps are required.
Advantageously, the master transponder includes a reset switch which may deactivate all of the alarms other than the one associated with the secondary transponder that is further than the specified distance from the master transponder, assisting in the location of the said secondary transponder. * 6
When the set of transponders includes a plurality of secondary transponders, it is advantageous that the master transponder includes a reset switch to enable a user to select which of the secondary transponders to activate. In use, the user places all of the secondary transponder devices of a set (which are in the sleep mode as described above) which they wish to use within the specified distance from the master transponder, and then presses the reset button. The reset button causes the master transponder to send a signal to all of the secondary transponders within the specified distance from the master transponder and establishes all of those transponders that will be used in the set for that period causing them to change from the low power sleep mode to a normal power mode.
An indication of the distance between the master transponder and secondary transponder or plurality of secondary transponders may be determined by measuring the attenuation of the two signals of different frequency being transmitted and received between the master transponder and the secondary transponder or plurality of secondary transponders. Should the signal strength drop below the level which represents the specified distance the secondary transponders are allowed to be from the master transponder, at least one alarm associated with a member of the set of transponders is activated.
An indication of the distance between the master transponder and the secondary transponder or plurality of secondary transponders may be determined by measuring the time it takes the two signals of different frequency to be transmitted between them. The master transponder and/or the secondary transponder or plurality of secondary transponders may include a clock to measure the time it takes for a signal to be sent back and forth between the transponders.
At least one of the alarms associated with any of the master transponder, secondary transponder or plurality of secondary transponders may be an audible alarm. At least one of the alarms associated with any of the master transponder, secondary transponder or plurality of secondary transponders may be a visual alarm. At least one of the alarms associated with the master transponder, secondary transponder or plurality of secondary transponders may be a vibrating alarm.
Any of the master transponder, secondary transponder or plurality of secondary transponders may be battery powered.
Any of the master transponder, secondary transponder or plurality of secondary transponders may be solar powered.
Any of the master transponder, secondary transponder or plurality of secondary transponders may be powered by an object to which they are attached. For example, a secondary transponder attached to a mobile phone may take charge from the mobile phone battery.
Preferably, the master transponder is arranged to be carried by a user. The master transponder may be arranged to be attached to the user. This may be by being associated with a strap or straps with by which the master transponder may be attached to the user. Alternatively, there may be a belt loop associated with the master transponder by which it may be attached to a belt being worn by the user.
The secondary transponder or plurality of secondary transponders may be arranged to be attached to another person or persons. This may be by being associated with a strap or straps by which the secondary transponder may be attached to the other person. * 8
The secondary transponder or plurality of secondary transponders may be arranged to be attached to an electronic device or devices. The secondary transponder may be associated with a clip, strap or adhesive patch in order that it can be attached to an electronic device, or it may be built into the electronic device itself. The secondary transponder or plurality of secondary transponders may be arranged to be attached to the personal belongings of a user, for example, their wallet, handbag or purse. The secondary transponder may be associated with a hard tag, or affixed into the garment or belongings, in order that it may be securely attached to the personal belonging of the user.
Advantageously, the invention comprises portable security apparatus comprising a master transponder and a secondary transponder, wherein each transponder is associated with an alarm, the transponders being arranged to transmit and receive two signals of different frequency back and forth between each other, the apparatus is arranged to ascertain from the signals a parameter dependant on the distance between the master transponder and the secondary transponder, and the apparatus is arranged to monitor the parameter such that, in use, should the parameter exceed a specified threshold then at least one of the alarms is activated.
The invention further provides a method of monitoring the distance between an object and a user, comprising the steps of: providing the user with a master transponder; providing the object with a secondary transponder associated with the master transponder; * 9 the master transponder transmitting a first pair of signals at first and second frequencies to the secondary transponder, the first and second frequencies being different; the secondary transponder receiving *the first and second signals and in response transmitting third and fourth signals at the third and fourth frequencies, the third and fourth frequencies being different; the master transponder receiving the third and fourth signals and in dependence thereon calculating whether the distance between the master transponder and the secondary transponder exceeds a specified distance, and activating an alarm in the event that the calculated distance between the master transponder and the secondary transponder exceeds a specified distance.
In the event that no signal from the master transponder is received by at least one secondary transponder, indicating that the secondary transponder is out of range of the master transponder (i.e. the distance between the master transponder and the secondary transponder exceeds the specified distance), then the alarm associated with the secondary transponder may be immediately activated. In the event that no signal is received from at least one secondary transponder by the master transponder, indicating it is out of range (i.e the distance between the master transponder and the secondary transponder exceeds the specified distance) then the alarm associated with the master transponder may be immediately activated.
Preferably, the first signal and third signal are the same frequency and the second signal and the fourth signal are the same frequency. * 10
The step of analysing the signals received by the master and secondary transponders may include comparing the attenuation of the signal with a preset value, and if the value is less than this it being deemed inappropriate to send a return signal.
Alternatively, the method may further include a step of the master transponder and/or secondary transponder measuring the time taken for a signal to be sent by a transponder, received by a different transponder and then back to the original transponder, thus indicating the distance between the master transponder and secondary transponder.
Embodiments of the invention will now be described, by way of example only, with reference to the accompany drawings of which: Figure 1 is a schematic representation of the portable security system, including a master transponder and secondary transponder; Figure 2 is an operational flow-chart of the process undertaken by the master transponder and secondary transponder as shown in Figure 1; Figure 3 shows a second embodiment of the invention, including a master transponder and two secondary transponders, when the distance between the master transponder and the two secondary transponders is within the specified distance; and Figure 4 shows the second embodiment of Figure 3 when one of the two secondary transponders is outside the specified distance.
Figure 1 shows a master transponder 1 and a secondary transponder 2. The master transponder comprises a first radio frequency circuit 3 and a second radio frequency circuit 4, information processing circuits 5, a battery power source 6, an on/off switch 7, a low power indicator 8, a reset button 9, an antenna 10 connected via a first splitter 11 to the first radio frequency circuit 3 and to the second radio frequency circuit 4. The master transponder is associated with an alarm 12, and are together enclosed in a housing 13. The secondary transponder 2 comprises a third radio frequency circuit 14 and a fourth radio frequency circuit 15, information processing circuits 16, a battery power source 17, a low power indicator 18, an antenna 19 connected to the third radio frequency circuit 14 and to the fourth radio frequency circuit 15 via a second splitter 20, and an alarm 21 all of which is enclosed in a housing 22.
Figure 1 shows signals being sent between the master transponder 1 and secondary transponder 2. A first signal 23 is sent by the first radio circuit 3 at frequency f 1, a second signal 24 is sent by the second radio frequency circuit 4 at frequency f 2, a third signal 25 is sent by the third radio frequency circuit 14 at frequency 1 and a fourth signal 26 is sent by the fourth radio frequency circuit 15 at frequency f 2. Each of the signals 23, 24, 25 and 26 includes a unique code (compared to the other signals mentioned) which may be used to identify the signal and which transponder it is going to or has come from. The frequencies, fi and f 2, and the codes are randomly selected during the manufacture of the master transponder 1 and secondary transponder 2 and set permanently for the lifetime of the transponders (i.e. in a manner which is not readily changeable by the user of the system). In this embodiment, the two frequencies f]. and f2 are 30kHz and 50GHz, * 12 respectively. The information processing circuits S and 16 include information relating to codes that have been randomly selected during manufacture and set into the transponders permanently for their lifetime. The information processing circuits 5 and 16 also include information relating to the strength of the two signals of different frequency that relate to the distance between the master transponder 1 and secondary transponder 2 when the signals are sent from one to the other. There is a specified signal strength permanently set into the transponders during manufacture that relates to the maximum distance the master transponder 1 and secondary transponder 2 may be separated before at least one alarm is activated.
Figure 2 is a flow-chart showing the steps of operation of the embodiment shown in Figure 1 when in use. At the start 27 the information processing circuits 5 of the master transponder 1 send coded and encrypted information (what will from now on be described as the "ask" code) to the first radio frequency circuit 3 and second radio frequency circuit 4. Then, via the splitter 11 and antenna 10, the "ask" code is sequentially transmitted 28 on the frequencies fi and f 2, as shown by arrows 23 and 24 of Figure 1. The "ask" code is then received sequentially 29 by the secondary transponder 2 via the antenna 19 and is sent to the information processing circuits 16 of the secondary transponder. The information processing circuits 16 register whether or not the message has been received in accordance with the specified protocols 30. The specified protocols include the level of attenuation (or strength) of the signals compared to a value preset in the information processing circuits 16. The attenuation relates to the distance between the master transponder 1 and secondary * 13 transponder 2 when the "ask" code is sent. Should the level of attenuation be such that the signal is less than the value that corresponds to the specified distance then the message has not been received in accordance with the protocols. The "ask" code also includes a code, the code being recognisable by the information processing circuits 16. If the code is not recognised by the information processing circuits 16 then the message has not been received in accordance with the protocols. In either case, the information processing circuit 16 then activates the alarm 21 associated with the secondary transponder 2. Should the signal strength be greater than the value that corresponds to the specified distance and the required code has been recognised then the message has been received in accordance with the protocols. The secondary transponder 2 then sends back an "all ok" code 32 sequentially on frequencies fi and f 2, as shown by the third signal 25 and fourth signal 26. It will of course be recognised by the skilled man that the order the signals are sent could vary.
For example, rather than the master transponder 1 sending two signals and then receiving two signals back, the master transponder could send one signal and then receive one signal back, followed by sending a further signal and receiving back another reply.
Where there is a plurality of secondary transponders, each one must have a uniquely identifiable signal in relation to the others in the set of secondary transponders.
This enables the master transponder 1 to identify each one individually and recognise when one is further than the specified distance. The signals may be uniquely identifiable with respect to the other signals because of the code they transmit, each code corresponding to a * 14 particular secondary transponder. The skilled man will also appreciate that the master transponder 1 could send and receive signals to and from each of the plurality of secondary transponders in turn. Alternatively, the master transponder 1 may send out a signal to all of the secondary transponders simultaneously and await the return signals.
The signals are received by the first radio frequency circuit 3 and second radio frequency circuit 4 and directed to the information processing circuits 5 of the master transponder, as shown by step 33, where the signals are checked regarding the required protocols as described for the "ask" code previously described. The information processing circuits 5 then analy8e whether the "all ok" code has been received from the secondary transponder, or if there is a plurality of secondary transponders if the "all ok" codes have been received from all of the secondary -transponders in the set (as mentioned above, each of which has a unique identification code).
If yes, then the process returns to the start 27 and begins again.
If the "all ok" signal is not received in accordance with the specified protocols, then the master transponder 1 sounds the alarm 12 with which it is associated, and also signals to the secondary transponder 2, or all of the secondary transponders if there is a plurality of transponders, to sound the alarm with which they are associated.
Figure 3 shows an embodiment of the invention where there is a master transponder 1 and two secondary transponders 34 and 35, where the secondary transponders are constructed in the same way as the secondary transponder 2.
The secondary transponders 34 and 35 have been activated by being brought within the specified distance to the master transponder 1 and the reset button of the master transponder 1 being pressed. This both turns on the secondary transponders 34, 35, taking them out of sleep mode in which they consume very little power, and on the receipt of a responding signal identifies to the master transponder 1 which secondary transponders it is monitoring. The specified distance that the secondary transponders 34, 35, are allowed to be from the master transponder 1 is indicated by the arrows Rn. While both of the secondary transponders 34, 35, are within this distance, as shown in figure 3, then none of the alarms sound. Figure 4 shows a situation when the secondary transponder 35 is at a distance greater than Rn from the master transponder 1. Each alarm associated with the master transponder 1 and secondary transponders 34, has been activated. The alarms within the specified distance Rn may be silenced by pushing the reset button 9 of the master transponder 1. The alarm associated with the secondary transponder 35, as it is not within the specified distance Rn, remains in its activated state.
Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. For example the master transponder may be worn by attachment to a wrist strap, a belt, or a necklace chain. The secondary transponder may be in the form of a hard tag, a bracelet or clip. The secondary transponder may be worn on clothing, attached to, or built in to, a mobile telephone or a satellite navigation unit. Also, in the above embodiment the first and second signals sent by the master transponder match the frequencies * 16 of the third and fourth signals sent by the secondary transponder. it may be possible to have signals such that either only one or none of the signals sent match each other in frequency.
For that reason, reference should be made to the claims for determining the true scope of the present invention. * 17