WO2007076564A1

WO2007076564A1 - System to prevent loss or theft of article

Info

Publication number: WO2007076564A1
Application number: PCT/AU2006/000910
Authority: WO
Inventors: Anand Madhukar Bhanushali
Original assignee: Bqt Solutions (Australia) Pty Ltd
Priority date: 2006-01-05
Filing date: 2006-06-29
Publication date: 2007-07-12

Abstract

A article guard system for protecting an article, particularly a mobile phone, from theft or loss and a method of doing the same are described. The system comprises a transmitter unit (100, 200) for attachment to an article and a receiver unit (300) for use with the transmitter unit (100, 200) to receive a wireless transmission of the transmitter unit (100, 200). The transmitter unit (100, 200) encodes a predefined ID code and wirelessly transmits the encoded ID code within a specified range. The receiver unit (300) has a registered ID code and generates an alarm if the receiver unit (300) cannot match the registered ID code with a decoded ID code from a wireless transmission of the transmitter unit (100, 200).

Description

SYSTEM TO PREVENT LOSS OR THEFT OF ARTICLE

RELATED APPLICATION

This patent application claims the benefit of, and is entitled to, the earlier filing date of Australian Provisional Patent Application No. 2006900055 filed on 5 January 2006 in the name of BQT Solutions (Australia) Pty Ltd, which is incorporated herein by reference.

TECHNICAL FIELD The present invention relates generally to systems and methods of preventing the loss or theft of articles, such as mobile telephones and other electronic devices.

BACKGROUND Systems for preventing the loss or theft of articles, especially mobile phones, have been proposed. U.S. Patent No. 5,796,338 issued to Mardirossan on 18 August 1998 describes a system for preventing loss of cellular phone or the like. The system includes a wireless transmitter in a cell phone for intermittently sending security signals to a pager worn by a user. The pager includes an alarm that is actuated when either the strength or amplitude of the security signal falls below a predetermined threshold or when the security signal is not received by the pager for a predetermined period of time.

European Patent No. 0581416 Bl granted Ren-Guey Yang on 06 August 1997 describes an alarm for reminding users of negligently left portable cellular telephone. An alarm system can receive local oscillatory control signals transmitted by a portable cellular telephone. The alarm system includes a super-high-frequency short-distance receiving circuit, detection circuits, and a warning circuit. The alarm system may be carried by a user and emits warning signals to remind the user whenever it fails to receive the local oscillatory control signals transmitted by the portable cellular telephone.

Such systems rely upon signal strength alone to determine whether or not to actuate an alarm. This can disadvantageously cause the system to falsely determine that a cellular phone or the like is within range of the alarm system. Thus, a need clearly exists for an improved system for preventing the loss or theft of articles, such as mobile telephones and other electronic devices.

SUMMARY

In accordance with an aspect of the invention, there is provided an article guard system for protecting a mobile phone from theft or loss, comprising: a transmitter unit for attachment to an article, the transmitter unit encoding a predefined ID code and wirelessly transmitting the encoded ID code within a specified range; and a receiver unit for use with the transmitter unit to receive a wireless transmission of the transmitter unit, the receiver unit having a registered ID code and generating an alarm if the receiver unit cannot match the registered ID code with a decoded ID code from a wireless transmission of the transmitter unit.

The predefined ID code may be dynamically generated. The predefined ID code may be dynamically generated each time the transmitter and receiver units are physically separated from each other.

The predefined ID code is a random or quasi-random number. The predefined ID code may have a variable length from one code to another.

The encoded ID code is wirelessly transmitted by the transmitter unit periodically at specified intervals and the receiver unit checks for reception of a transmission from the transmitter unit at corresponding specified intervals.

The alarm may be generated if the receiver unit and the transmitter unit are separated by more than the specified range, so that a decoded ID code is not available at the receiver unit for comparison with the registered ID code. The alarm may be generated if the decoded ID code and the registered ID code do not match.

The transmitter unit may comprise an electronic circuit capable of being embedded inside or attached externally to a mobile phone. The transmitter and receiver units may each be battery powered. The receiver unit may comprise a battery for powering the receiver unit. The transmitter may comprise a battery for powering the transmitter unit. The transmitter unit may comprise a cable for connection with a battery of the article.

The predefined ID code may be encoded using a modulation technique. The modulation technique may be Amplitude Shift Keying (ASK).

The predefined ID code may be encrypted.

The transmitter unit may comprise: a microprocessor for providing the predefined ID code; a modulator coupled to the microprocessor for modulating the predefined ID code with a carrier signal to provide a modulated signal; and an antenna for transmitting the modulated signal.

The receiver unit may comprise: an antenna for receiving a wireless transmission; a demodulator coupled to the antenna for demodulating the wireless transmission; a microprocessor coupled to the demodulator for comparing an ID code derived from a demodulated wireless transmission with the registered ID code; and an alarm device for generating an alarm signal in response to the microprocessor determining that the ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available.

The article may comprise a mobile phone.

In accordance with another aspect of the invention, there is provided a method for protecting an article from theft or loss. The method comprises the steps of: encoding using the transmitter unit attached to an article a predefined ID code; wirelessly transmitting using the transmitter unit the encoded ID code within a specified range; providing a receiver unit for use with the transmitter unit to receive a wireless transmission of the transmitter unit, the receiver unit having a registered ID code; and generating an alarm if the receiver unit cannot match the registered ID code with a decoded ID code from a wireless transmission of the transmitter unit.

The transmitter unit may comprise an electronic circuit capable of being embedded inside or attached externally to a mobile phone.

The transmitter and receiver units may each be battery powered. The receiver unit may comprise a battery for powering the receiver unit. The transmitter may comprise a battery for powering the transmitter unit. The transmitter unit may comprise a cable for connection with a battery of the article.

The predefined ID code may be encrypted. The transmitter unit may comprise: a microprocessor for providing the predefined ID code; a modulator coupled to the microprocessor for modulating the predefined ID code with a carrier signal to provide a modulated signal; and an antenna for transmitting the modulated signal.

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The receiver unit may comprise: an antenna for receiving a wireless transmission; a demodulator coupled to the antenna for demodulating the wireless transmission; a microprocessor coupled to the demodulator for comparing an ID code derived from a demodulated wireless transmission with the registered ID code; and an alarm device for io generating an alarm signal in response to the microprocessor determining that the ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available.

The article may comprise a mobile phone.

I₅

In accordance with a further aspect of the invention, there is provided a transmitter unit for attachment to an article for protecting an article from theft or loss, comprising: a microprocessor for providing a predefined ID code; a modulator coupled to the microprocessor for modulating the predefined ID code with a carrier signal to provide a 0 modulated signal; and an antenna for wirelessly transmitting the modulated signal at specified intervals within a specified range for reception by a receiver unit.

The predefined ID code may be dynamically generated. The predefined ID code may be dynamically generated each time the transmitter and receiver units are physically 25 separated from each other.

0 The encoded ID code is wirelessly transmitted by the transmitter unit periodically at specified intervals and the receiver unit checks for reception of a transmission from the transmitter unit at corresponding specified intervals. The transmitter unit may be capable of being embedded inside or attached externally to an article. The transmitter unit may further comprise a battery for powering the transmitter unit.

The transmitter unit may further comprise a cable for connection with a battery of an article.

The predefined ID code may be encoded using a modulation technique.

The transmitter unit may further comprise a phase-locked loop for generating the carrier signal.

The article may comprise a mobile phone.

In accordance with a still further aspect of the invention, there is provided a receiver unit for protecting an article from theft or loss, comprising: an antenna for receiving a wireless transmission; a demodulator coupled to the antenna for demodulating the wireless transmission; a microprocessor coupled to the demodulator for comparing an ID code derived from a demodulated wireless transmission with the registered ID code; and an alarm device for generating an alarm signal in response to the microprocessor determining that the ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available.

The predefined ID code is a random or quasi-random number. The predefined ID code may have a variable length from one code to another. The encoded ID code is wirelessly transmitted by the transmitter unit periodically at specified intervals and the receiver unit checks for reception of a transmission from the transmitter unit at corresponding specified intervals.

The receiver unit may further comprise a battery for powering the receiver unit.

The article may comprise a mobile phone.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are described hereinafter with reference to the drawings, in which:

Figs. IA and IB are perspective views of a transmitter for an article guard system in accordance with an embodiment of the invention;

Fig. 2 is a perspective view of a transmitter for an article guard system in accordance with another embodiment of the invention;

Figs. 3 A, 3B and 3C are perspective views of a receiver with a battery for an article guard system in accordance with an embodiment of the invention;

Fig. 4 is a flow diagram of a process for transmitting an ID code in accordance with a further embodiment of the invention;

Fig. 5 is a flow diagram of a process for receiving an ID code in accordance with another embodiment of the invention;

Fig. 6 is a block diagram of the transmitter for an article guard system of Figs. 1 and 2; and

Fig. 7 is a block diagram of the receiver for an article guard system. DETAILED DESCRIPTION

An article guard system and a method of guarding an article are described in detail hereinafter. In the following description, numerous specific details are set forth such as modulation techniques, ranges of wireless communications, and the like. However, in the light of this disclosure, modifications and/or substitutions may be made by those skilled in the art without departing from the scope and spirit of the invention. In other instances, details well known to those skilled in the art may be omitted so as not to obscure the invention.

The embodiments of the invention provide an article guard system for protecting a article from theft or loss. The system uses wireless technology to provide a virtual electronic leash, which has a range of about 1 to about 2 meters (known as a person's comfort zone). Other ranges may be practiced without departing from the scope and spirit of the invention. The system has particular application as a mobile phone guard system, to prevent the loss or theft of a mobile phone. However, the system may have application to other articles.

The embodiments of the invention utilize a random or quasi-random (for ease of description, the term random is used only) ID code exchanged between a transmitter unit and a receiver unit to a establish a relationship between the receiver and the particular transmitter. The transmitter unit transmits the ID code, and while the receiver initializes itself the receiver starts looking only for that code transmission from its coupled transmitter. Any other transmissions are discarded. This enables multiple units to operate in the same vicinity without false detections. The random ID code may be generated using a random code generator. The ID code may be generated to be of any length, as defined in firmware. The ID code may be generated on the fly each time the transmitting unit starts or initializes. The code generation is done by the random code generator, which keeps changing the ID code on the fly preferably.

The system comprises two principal components: A transmitter The unit is an electronic circuit embedded inside or unit (TX): attached externally to a mobile phone. The unit may draw power from the battery of the mobile phone, or may be self-powered with a small button cell battery. The unit transmits the ID code. The ID code is preferably encrypted. The transmission may be made using any of a number of modulation techniques at predetermined intervals. For example, the ID code may be transmitted using Amplitude Shift Keying (ASK) a specified time intervals using a specified transmitting frequency (e.g., 434 KHz).

A receiver unit The unit is an intelligent unit that groups with its (RX): transmitter at power up to build the noted electronic leash. Once a successful TX-RX pair build up has been completed, this activation may be indicated to a user to indicate the system is ready to be used. For example, the indication may be two beeps from the receiver. After the electronic leash is in place, if the mobile phone with the transmitter unit (TX) is beyond the range of 1 to 2 meters, the receiver unit (RX) generates an alarm to alert that the mobile phone exceeds the designated range between the TX and RX units.

This system may be tamper proof. A tamper switch may be installed at the bottom of transmitter unit (TX). If the TX unit is removed from the mobile phone, the tamper switch is released. This immediately interrupts or stops transmission and is considered by the RX unit as alarm sequence. If the transmitter unit (TX) is removed from the mobile phone, an alarm is automatically activated at the receiver unit (RX). The transmitter unit (TX) causes minimum interference with mobile phone usage and the voice clarity produced by the mobile phone. A small switch may be used so that the switch enables the transmitter unit when it is split apart from the receiver unit. When the device is turned off (e.g., to save power of the battery) attaching the RX unit to the TX unit switches off both units. When the RX and TX units are detached from each other (i.e., "split or separate"), the RX and TX units initialize and generate a new random code to identify each other. That is, each time the transmitter/receiver pair is split, a new random ID code is generated.

The RX unit may be powered from the mobile phone's battery. Alternatively, external batteries or rechargeable batteries may be use. For example, the rechargeable batteries may be charged using the USB port of a computer. The TX unit may be powered similarly using such batteries. Still further the battery of the RX unit (the same applies to the TX unit) may be rechargeable and coupled to a solar cell device for recharging the battery. The solar cell device may be coupled to the RX unit or built into its housing, for example.

I. Transmitter Unit TTX)

Figs. IA and IB shows part of the article guard system 100, more particular a phone guard system. A partially disassembled mobile phone 110 is shown in Fig. IA. The battery 130 is separated from the compartment 120 of the body of the mobile phone 110 adapted to fit and house the battery 130. A transmitter unit (TX) 150 is connected by a flex or ribbon cable or FFC cable (flat flexible cable) 160 to a battery connection interface 140, which is provided in the compartment 120 of the mobile phone 110. As shown in Fig. IB, the battery 130 may be joined together with the phone body 110, with the flex cable 160 extending from the interior of the compartment 120 (of Fig. IA) to the TX unit 150, which is mounted or affixed to the back surface of the battery 130 or the phone body 110. If the TX unit is self powered, a battery may be encapsulated in the body of TX unit (see Fig. 2).

In another embodiment of the invention, the article guard system 200 is similar to that of Fig. 1 except that a transmitter unit (TX) 250 is self powered using a small battery. The mobile phone 210 is the same as that 110 of Fig. IA and is not described further for - l i ¬

the sake of brevity. Consequently, the TX unit 210 does not require a flex cable to connect the TX unit 210 to the phone's battery for power. A receiver unit (RX) 270 is also shown, which is also self-powered with an encapsulated batter. The RX unit 270 has a metallic tab and the protrusion is a beeper.

Fig. 6 is a block diagram of a transmitter unit (TX) 600 that may be used as the TX unit 150, 250 of Figs. 1 and 2. The TX unit 600 comprises a microprocessor unit 610, a voltage controlled oscillator (VCO) 670, a modulator 616, and an antenna 620. The TX unit 600 is provided power from a battery 630, which may represent the battery of the mobile phone or a separate battery provided with the TX unit 600. For example, the battery 630 may have a voltage of 3.6V from the phone battery or 3 V from a separate battery. A reference oscillator circuit 640 provides a reference frequency signal to a phase and frequency detector 650. An output of the detector 650 is provided as input to the VCO 670. One output of the VCO 670 is provided as input to a prescaler circuit 660, which performs frequency division. For example, the prescaler circuit 660 may have a value of 64 or 128. The output of this circuit 660 is provided as another input of the phase and frequency detector 650. The detector 650, the prescaler circuit 660, and the VCO 670 work in the manner of a phase-locked loop well known to those skilled in the art. The output of the VCO 670 is provided as an input of the modulator 616.

The microprocessor unit 610 may comprise a microprocessor 612 and a read only memory (ROM). The ROM 614 stores an ID code for the TX unit 600. It will be appreciated by those skilled in the art, in the light of this disclosure, that while a ROM 614 is shown in Fig. 6 other non-volatile memories or stores may be used without departing from the scope and spirit of the invention. A random ID code is provided for modulation. The ID code (e.g., Oxab Oxff) of the transmitter unit (TX) 600 is random to each transmitter and may be of variable length. The ID code is preferably encrypted by the transmitter unit (TX) 600 and decoded by the corresponding receiver unit (RX). The microprocessor 612 may be implemented in a manner well known to those skilled in the art and be coupled to a memory or store having computer program code or microprocessor instructions for operating the microprocessor 612 in a specified manner. The microprocessor 612 may implement encryption. The ID code (encrypted or not) may then be provided as another input to the modulator 616. As noted hereinbefore, the modulator 616 may implement ASK or another modulation technique. The modulated signal produced by the modulator 616 is transmitted via the antenna. A band pass filter 618 filters the modulated signal from the modulator 616 prior to radiating the signal using the antenna 620. The filter 618 may be comprised of inductive and capacitive elements (L/C), as well as other elements, well known to those skilled in the art.

H. Operation of Transmitter Unit (TX)

Fig. 4 illustrates operation of the transmitter unit 100, 200, 600 in greater detail. In step 410, processing of the transmit process 400 commences. In step 412, the transmitter unit (TX) 412 is powered up. The microprocessor is initialized. In step 414, a check is made of the tamper switch to determine if the tamper proofing integrity is maintained.

This is an optional step and in another embodiment may be omitted. If step 414 determines that the transmitter unit (TX) has been tampered with (No), functioning of the transmitter unit (TX) stops in step 416. Otherwise, if the tamper proofing is okay

(Yes), processing continues at step 418.

In step 418, the length of an ID code is determined. That is, the length of the ID code may be specified dynamically. Thus, a code of random length may be generated. Alternatively, the step 418 may be omitted if the code length is fixed. In step 420, a random ID code of the specified length is generated. This step may involve the microprocessor 612 reading the ID code from ROM 614. In step 422, the generated ID code is encrypted and preferably a checksum is added to the encrypted ID code. The resulting ID code is provided to the modulator 616 as input. The modulator 616 modulates the carrier signal using the input ID code, which is then transmitted by the transmitter in step 424. This preferably involves one-way communications from the transmitter. Processing continues at step 432.

In step 432, a delay is implemented, so that the transmitter unit (TX) may transmit at specified periodic times. In step 434, the tamper switch is checked, per step 414. If the tamper proofing integrity is not maintained (No), processing terminates ("stop functioning" and an alarm will be activated in the receiver) in step 436 and otherwise (Yes) processing returns to step 424.

A receiver unit (RX) is described hereinafter which may be practiced in conjunction with the transmitter unit (TX) to implement the article guard system.

III. Receiver Unit (RX)

Figs. 3A to 3C show another part of the article guard system 100. Fig. 3A is a top plan view of a receiver unit (RX) 300 implemented in a case. The case may be a designer case, which may be plastic encapsulation used to make the case fashion friendly or wearable. Each receiver unit (RX) is intelligent to pair/couple up with the corresponding transmitter unit (TX) to track movement of its paired/coupled transmitter unit (TX). This enables KKJTX pairs of article guard systems to be operated in proximity of each other without any collision or false alarms. The receiver unit (RX) 300 may be detachable. The RX unit 300 may be fitted into any designer case to suit the user's taste. This may make the RX unit 300 comfortable to wear on any occasion or style of clothing.

Figs. 3B and 3 C are perspective views of the same receiver unit (RX) 300 in a closed and opened state, respectively. As shown in Figs. 3A and 3B, the receiver unit (RX) 300 has one or more holes or apertures in at least one surface for emission of audible signals or alarms. In this embodiment, there are 5 such holes, but other numbers of holes may be practiced. Within the casing of the receiver unit (RX) 300, there is provided electronics and associated circuitry (not shown) for receiving and processing a modulated signal containing an ID code, as well as other functions. A speaker or beeper (not shown) is also provided to generate the audible signal or alarm.

Fig. 7 is a block diagram of a receiver unit (RX) 700 that may be used as the RX unit 300 of Fig. 3. The RX unit 700 comprises a microprocessor unit 710, an antenna 720, and demodulation circuitry. The RX unit 700 is provided power from a battery 730, which may be provided by a separate battery provided with the RX unit 700. The antenna 720 can receive a transmitted signal from the TX unit. A radio frequency (RF) amplifier 722 amplifies a signal received by the antenna 720 and provides the amplified signal to a mixer 724, which also receives a reference signal from an oscillator 726 to demodulate the received signal. As noted hereinbefore, the demodulator 724 may implement demodulation for ASK or another modulation technique. The output of the mixer 724 is provided to an intermediate frequency (IF) amplifier 728, before the signal is filtered by an IF filter 730. The filter output is coupled to a limiter 740. The limiter 740 provides a reference frequency to demodulate the frequency to get the data signal out.

The output of the limiter 740 is provided to a buffer 732. The output of buffer 732 is provided via a resistive element 750 to a comparator 760. The other input to comparator 760 is a specified reference voltage. This may be provided via resistive elements 752 and 754 and associated capacitors in a low pass filter configuration in combination with a voltage Vcc, which is the same as the battery voltage. The resistive elements 752, 754 act as a voltage divider. The output of the comparator 760 produces an output signal that is provided as input to the transistor 770, which acts as a switch intermittently coupled to ground, dependent upon the output of the comparator 760. The collector of the transistor 770 is connected to a microprocessor unit 710 and the emitter is connected coupled to ground.

Operation of the transistor 770 provides a demodulated signal to the microprocessor 712 of the microprocessor 710. The microprocessor unit 710 also contains a code compare module, which can compare a received demodulated signal with the ID code stored in the receiver unit (RX) 700 that the RX unit 700 expects to receive. The microprocessor 712 may be implemented in a manner well known to those skilled in the art and be coupled to a memory or store having computer program code or microprocessor instructions for operating the microprocessor 712 in a specified manner. The microprocessor 712 may implement decryption for decrypting the demodulate signal to extract the random ID code that is received by the RX unit 700. The microprocessor unit 710 is also coupled to a speaker or beeper 716 in the RX unit 700 to generate an audible signal or alarm, e.g. when a random ID code is not received in a specified time interval. IV. Operation of Receiver Unit (RX)

Fig. 5 illustrates operation of the receiver unit 300, 700 in greater detail. In step 510, processing of the receive process 500 commences. In step 512, the receiver unit (RX) is powered up. In step 514, a check is made to determine if a transmission is received. If the transmitted code is not received (No), processing continues at step 516 and the RX unit enters a sleep mode. Otherwise, if a transmitted code is received (Yes), processing continues at step 518. The RX unit looks for the specific type of stream of data bytes after decoding data. Once the RX unit has decoded and found the specific type of streamed data, the RX unit stores the decoded data in memory for further comparison. The RX unit acknowledges with a specified number (e.g., two) of beeps that the TX and RX units are ready to use. In step 518, a stored ID code is read and decoded. A comparison may be made by firmware, which may be carried out by the microprocessor. In step 520, the ID code decoded is registered with the microprocessor. In step 522, the receiver indicates that a code has been received and decoded. This may be done, for example, by generating a beep. In step 524, a transmission received by the RX unit is read. Every time an ASK transmission is received from the TX unit, the RX unit looks for the same data (ID code) in the data stream, which is stored earlier when the RX unit acknowledged that system was ready to use. In step 526, a code is decoded from the transmission and is compared with the previously registered code to determine a match. If the two codes match (Yes), processing continues at step 528, in which a specified delay matching that of the TX unit is implemented before processing returns to step 524. Otherwise, if the two codes do not match (No) in step 526, an alarm is activated in step 530, e.g. an alarm may be sounded. Processing then continues at step 532 in which a transmission is read. In step 534, a code is decoded from the received transmission and compared with the previously registered code_* If the two do not match (No), processing continues at step 530 and the alarm continues to be activated. Otherwise, if the two codes, do match in step 534 (Yes), processing continues at step 536. In step 536, the alarm is turned off or otherwise deactivated, before processing continues at step 524. The article guard system therefore aims to remind or warn users that their mobile phone may be lost or stolen. Mobile phones are personal devices that contain large amounts of data with prime importance to their owner. In this day and age, many people do not use diaries to store important information. Instead, mobile phones are often used to store details such as credit card numbers, account details, contacts and "to-do" lists. This makes a mobile phone a handheld electronic device with considerable importance in many people's lives. Therefore, losing a mobile phone is not only a monetary loss, but also a personal loss.

Article guard systems and methods of guarding an article, especially a mobile phone, have been described. In view of this disclosure, modifications and/or substitutions may be made by those skilled in the art without departing from the scope and spirit of the invention.

Claims

CLAIMSThe claims defining the invention are as follows:

1. An article guard system for protecting a mobile phone from theft or loss, comprising: a transmitter unit for attachment to an article, said transmitter unit encoding a predefined ID code and wirelessly transmitting said encoded ID code within a specified range; and a receiver unit for use with said transmitter unit to receive a wireless transmission of said transmitter unit, said receiver unit having a registered ID code and generating an alarm if said receiver unit cannot match said registered ID code with a decoded ID code from a wireless transmission of said transmitter unit.

2. The system according to claim 1, wherein said predefined ID code is dynamically generated.

3. The system according to claim 2, wherein said predefined ID code is dynamically generated each time said transmitter and receiver units are physically separated from each other.

4. The system according to any one of claims 1 to 3, wherein said predefined ID code is a random or quasi-random number.

5. The system according to any one of claims 1 to 4, wherein said predefined ID code has a variable length from one code to another.

6. The system according to claim 1, wherein said encoded ID code is wirelessly transmitted by said transmitter unit periodically at specified intervals and said receiver unit checks for reception of a transmission from said transmitter unit at corresponding specified intervals.

7. The system according to claim 1 or 6, wherein said alarm is generated if said receiver unit and said transmitter unit are separated by more than said specified range, so that a decoded ID code is not available at said receiver unit for comparison with said registered ID code.

8. The system according to claim 1, 6, or 7, wherein said alarm is generated if said decoded ID code and said registered ID code do not match.

9. The system according to claim 1, wherein said transmitter unit comprises an electronic circuit capable of being embedded inside or attached externally to a mobile phone.

10. The system according to claim 1, wherein said transmitter and receiver units are each battery powered.

11. The system according to claim 10, wherein said receiver unit comprises a battery for powering said receiver unit.

12. The system according to claim 10 or 11, wherein said transmitter comprises a battery for powering said transmitter unit.

13. The system according to claim 10 or 11, wherein said transmitter unit comprises a cable for connection with a battery of said article.

14. The system according to claim 1, wherein said predefined ID code is encoded using a modulation technique.

15. The system according to claim 14, wherein said modulation technique is Amplitude Shift Keying (ASK).

16. The system according to claim 14, wherein said predefined ID code is encrypted.

17. The system according to claim 1, wherein said transmitter unit comprises: a microprocessor for providing said predefined ID code; a modulator coupled to said microprocessor for modulating said predefined ID code with a carrier signal to provide a modulated signal; and an antenna for transmitting said modulated signal.

18. The system according to claim 1, wherein said receiver unit comprises: an antenna for receiving a wireless transmission; a demodulator coupled to said antenna for demodulating said wireless transmission; a microprocessor coupled to said demodulator for comparing an ID code derived from a demodulated wireless transmission with said registered ID code; and an alarm device for generating an alarm signal in response to said microprocessor determining that said ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available.

19. A method for protecting an article from theft or loss, said method comprising the steps of: encoding using said transmitter unit attached to an article a predefined ID code; wirelessly transmitting using said transmitter unit said encoded ID code within a specified range; providing a receiver unit for use with said transmitter unit to receive a wireless transmission of said transmitter unit, said receiver unit having a registered ID code; and generating an alarm if said receiver unit cannot match said registered ID code with a decoded ID code from a wireless transmission of said transmitter unit.

20. The method according to claim 19, wherein said predefined ID code is dynamically generated.

21. The method according to claim 20, wherein said predefined ID code is dynamically generated each time said transmitter and receiver units are physically separated from each other.

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22. The method according to any one of claims 19 to 21, wherein said predefined ID code is a random or quasi-random number.

23. The method according to any one of claims 19 to 22, wherein said I₀ predefined ID code has a variable length from one code to another.

24. The method according to claim 19, wherein said encoded ID code is wirelessly transmitted by said transmitter unit periodically at specified intervals, and further comprising the step of checking for reception by said receiver unit of a is transmission from said transmitter unit at corresponding specified intervals.

25. The method according to claim 19 or 24, wherein said alarm is generated if said receiver unit and said transmitter unit are separated by more than said specified range, so that a decoded ID code is not available at said receiver unit for 0 comparison with said registered ID code.

26. The method according to claim 19, 24, or 25, wherein said alarm is generated if said decoded ID code and said registered ID code do not match.

5 27. The method according to claim 19, wherein said transmitter unit comprises an electronic circuit capable of being embedded inside or attached externally to a mobile phone.

28. The method according to claim 19, wherein said transmitter and 0 receiver units are each battery powered.

29. The method according to claim 28, wherein said receiver unit comprises a battery for powering said receiver unit.

30. The method according to claim 28 or 29, wherein said transmitter comprises a battery for powering said transmitter unit.

31. The method according to claim 28 or 29, wherein said transmitter unit comprises a cable for connection with a battery of an article.

32. The method according to claim 19, wherein said predefined ID code is encoded using a modulation technique.

33. The method according to claim 32, wherein said modulation technique is Amplitude Shift Keying (ASK).

34. The method according to claim 32, wherein said predefined ID code is encrypted.

35. The method according to claim 19, wherein said transmitter unit comprises: a microprocessor for providing said predefined ID code; a modulator coupled to said microprocessor for modulating said predefined ID code with a carrier signal to provide a modulated signal; and an antenna for transmitting said modulated signal.

36. The method according to claim 19, wherein said receiver unit comprises: an antenna for receiving a wireless transmission; a demodulator coupled to said antenna for demodulating said wireless transmission; a microprocessor coupled to said demodulator for comparing an ID code derived from a demodulated wireless transmission with said registered ID code; and derived from a demodulated wireless transmission with said registered ID code; and an alarm device for generating an alarm signal in response to said microprocessor determining that said ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available. an alarm device for generating an alarm signal in response to said microprocessor determining that said ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available.

37. A transmitter unit for attachment to an article for protecting an article from theft or loss, comprising: a microprocessor for providing a predefined ID code; a modulator coupled to said microprocessor for modulating said predefined ID code with a carrier signal to provide a modulated signal; and an antenna for wirelessly transmitting said modulated signal at specified intervals within a specified range for reception by a receiver unit.

38. The transmitter unit according to claim 37, wherein said predefined ID code is dynamically generated.

39. The transmitter unit according to claim 38, wherein said predefined ID code is dynamically generated each time said transmitter and receiver units are physically separated from each other.

40. The transmitter unit according to any one of claims 37 to 39, wherein said predefined ID code is a random or quasi-random number.

41. The transmitter unit according to any one of claims 37 to 40, wherein said predefined ID code has a variable length from one code to another.

42. The transmitter unit according to claim 37, wherein said transmitter unit is capable of being embedded inside or attached externally to an article.

43. The transmitter unit according to claim 37, further comprising a battery for powering said transmitter unit.

44. The transmitter unit according to claim 37, further comprising a cable for connection with a battery of an article.

45. The transmitter unit according to claim 40, wherein said predefined ID code is encoded using a modulation technique.

46. The transmitter unit according to claim 37, further comprising a phase-locked loop for generating said carrier signal.

47. A receiver unit for protecting an article from theft or loss, comprising: an antenna for receiving a wireless transmission; a demodulator coupled to said antenna for demodulating said wireless transmission; a microprocessor coupled to said demodulator for comparing an ID code derived from a demodulated wireless transmission with said registered ID code; and an alarm device for generating an alarm signal in response to said microprocessor determining that said ID codes do not match or a specified time interval has been exceeded without an ID code derived from a demodulated wireless transmission being available.

48. The receiver unit according to claim 46, wherein said predefined ID code is dynamically generated.

49. The receiver unit according to claim 47, wherein said predefined ID code is dynamically generated each time a transmitter and said receiver unit are physically separated from each other.

50. The receiver unit according to any one of claims 46 to 48, wherein said predefined ID code is a random or quasi-random number.

51. The receiver unit according to any one of claims 46 to 49, wherein said predefined ID code has a variable length from one code to another.

52. The receiver unit according to claim 50, further comprising a battery for powering said receiver unit.

53. The system according to any one of claims 1-18, wherein said article comprises a mobile phone.

54. The method according to any one of claims 19-36, wherein said article comprises a mobile phone.

55. The transmitter unit according to any one of claims 37-45, wherein said article comprises a mobile phone.

56. The receiver unit according to any one of claims 46-51 , wherein said article comprises a mobile phone.