SE532443C2 - Method and device for wireless function with adjustable sensitivity - Google Patents

Description

20 25 30 35 aa: aa fi 2 elements. The oscillator is preferably of the superregenerative type and exhibits negative resistance to the received signal.

WO 96/08086 describes a micropower transponder using a superregenerative receiver in which the throttled oscillator is located outside the regenerative transistor. The throttled oscillator supplies an exponentially decaying waveform rather than the usual sine wave to achieve high sensitivity at current levels in the microampere range.

PCT / SE2007 / 000768 describes a receiver circuit with low power consumption.

The receiver circuit is activated when receiving a radio frequency signal with a specific frequency and with an amplitude sufficient to activate the receiver circuit.

However, during the lifetime of the identification tag, the receiver can be activated by temporary radio frequency sources in the vicinity of the tag. When the receiver is activated, it draws power until it detects that the activation was not a correct activation signal, turning it off.

If the tag is inadvertently activated too many times, the battery may run out.

SUMMARY OF THE INVENTION Accordingly, the present invention aims to counteract, avoid or eliminate one or more of the above shortcomings and disadvantages within the scope, individually or in any combination.

According to one aspect of the invention, there is provided a method of operating an electronic device provided with a receiver for receiving signals transmitted by transmitters, comprising: first operating the electronic device in a meta-stable first mode of operation; operating the electronic device in a second oscillating ståndction state, wherein the electronic device oscillates at a predetermined oscillation frequency; transmitting the electronic device from said first operating state to said second operating state by means of a bias circuit which is triggered by a wirelessly transmitted signal having a predetermined signal frequency and power level and which is received by an antenna of the electronic device; terminating said second operating state and transmitting the device to said metastable first operating state by means of an extinguishing circuit; said bias circuit comprising a first sensitivity state, wherein the bias circuit has a first sensitivity, and a second sensitivity state, wherein the bias circuit has a second sensitivity greater than the first sensitivity, and transmitting the bias circuit fi from the first sensitivity state to the second the sensitivity state by receiving a wirelessly transmitted signal.

In one embodiment, the method may comprise that said wirelessly transmitted signal is an electromagnetic signal received by said antenna. The wirelessly transmitted signal may be an infrared signal, a laser signal, a radioactive signal or an ultrasonic signal.

In a further aspect, an electronic device is provided, provided with a receiver for receiving a first signal with a first frequency transmitted by a transmitter; 532. 443 3 comprising an oscillation circuit biased for operation in an inactive, metastable first function state and adapted to operate in a second oscillating state of operation, wherein the oscillation circuit oscillates at a predetermined oscillation frequency; a low voltage circuit for transmitting the oscillation circuit from said first fi operating state to said second operating state by triggering with a signal having a ßrated signal vens sequence and power level and received by an antenna of said electronic device; a loop circuit for terminating said second stillmction state and transferring the device to said first metastable operating state; said bias circuit comprising a first sensitivity state, wherein the bias circuit has a first sensitivity and a second sensitivity state where the bias circuit has a second sensitivity greater than the first sensitivity; and a transmission circuit for transmitting the bias circuit from the first solitude state to the second sensitivity state upon receipt of a wireless transmitted signal.

According to one embodiment, the device may comprise that said wirelessly transmitted signal is an electromagnetic signal received by said antenna. Said wirelessly transmitted signal may be an infrared signal, a laser signal, a radioactive signal or an ultrasonic signal.

According to another embodiment, the oscillation element may comprise an amplifier element and an alter element connected to form an oscillating circuit.

BRIEF DESCRIPTION OF THE DRAWINGS Additional objects, features and advantages of the invention will become apparent from the following detailed description of embodiments of the invention, taken in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of an RFID system in which the invention may be used.

Fig. 2 is a schematic wiring diagram of a prior art identification tag used in an RFID system according to fig 1.

Fig. 3 is a circuit diagram of an embodiment of a device according to the invention.

Fig. 4 is a detailed circuit diagram of an embodiment in which the receiver circuit is used in a heterodyne receiver.

Fig. 5 is a detailed circuit diagram of a circuit arrangement according to a further embodiment.

Fig. 6 is a detail of the wiring diagram in fi g 5 where the bias circuit is adjustable.

Fig. 7 is a gain diagram of a non-linear amplifier according to the embodiment of fig 5.

Fig. 8 is a diagram of the bandpass characteristics of a bandpass filter in the embodiment of Fig. 5. Fig. 9 is a circuit diagram of a device comprising a "wake-up" property. Fig. 10 is a circuit diagram of a device comprising your receiver circuits.

Fig. 11 is a detailed circuit diagram similar to Fig. 5 of another titration guide.

Fig. 12 'is a circuit diagram similar to Fig. 11 with a different bias circuit.

Fig. 13 is a detailed circuit diagram of a circuit according to a further embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS The embodiments described below indicate the best embodiment and enable one skilled in the art to accomplish the invention. The various features of the desiccants can be combined in other ways than those described below. The invention can be carried out in many different ways and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this description will be accurate and complete and will fully reflect the scope of the invention to one skilled in the art.

The invention is limited only by the appended claims.

Fig. 1 is a schematic diagram showing an RFID system 10 comprising a reader 11 and your marks or tags 12, 13, 14, 15, 16. Although five tags are shown, such a system may include a large number of tags, wherein some are within the realm of a specific reader 1 1.

The reader ll comprises a transceiver (transmitter / receiver), which transmits a radio signal with predetermined fi sequences and listens for response signals fi- from the tags.

Tag yarn can have different configurations depending on the system.

The tag may be a passive device with selective absorption of energy, for example at said predetermined frequency. The reader 11 can sense the absorption and determine a property of the tag. The passive device does not need a power supply.

A more versatile, active tag includes a receiver and a transmitter. The receiver is a receiver with low power consumption, which (intermittently) listens to radio signals transmitted by the reader. The tag is activated at regular intervals. When the receiver senses a radio signal, for example in a predetermined frequency range, a power source is connected to the transmitter to transmit a response. The response may be a confirmation signal and / or may include information, such as the identity of the tag and / or additional data. The internal power supply can be supplemented with power obtained from a radio signal transmitted by the reader. However, the receiver is activated at regular or controlled intervals even if there is no reader within range, thereby consuming power. 10 15 20 25 30 35 532 443 5 - The tag can have an identity and can respond to readers only if the identity matches a signal sent by the reader. Such an identity can be a series of frequencies transmitted by the reader. The reader may be arranged to transmit signals at different frequencies in a frequency band, for example the frequencies f0 to t79 included in a free band in the 2.4 GHz range, which is open to low level applications. Such a frequency band may comprise 80 bands with a frequency distance of 1 MHz, compare the Bluetooth® standard. For example, the reader can send the sequence series f1, f5, 133, i2 and the tag having the identity vector (1, 5, 33, 2) will be activated and send a response.

Tags are produced in large quantities and should be as cheap as possible. Thus, there is a need for a design that is as simple as possible. Furthermore, the current noise should be minimized so that small batteries can be used. The batteries must last at least over the life of the product, which can be, for example, 5 years or more. The receiver in the tag has according to the prior art been constructed as a heterodyne receiver, as shown in fi g 2. The tag 20 comprises an antenna 21 connected to a broadband amplifier 22 with an output connected to a mixer 23. The signal from the antenna is mixed with a signal which has a predetermined frequency from an oscillator 24, such as a VCO, a voltage controlled oscillator. The difference signal from the mixer 23 is fed to a narrowband intermediate frequency amplifier IF 25 and the amplified signal is output to an output contact which is connected to some form of evaluation circuit, which is not shown. Thus, the frequency 24 of the VCOzn determines which antenna signal frequency is amplified by the intermediate frequency amplifier 25. However, the current dissipation of such a receiver becomes relatively large. Activating the receiver for only short periods of time at long intervals reduces the current roar of the tag 20. However, if the time interval is too long, the tag may risk missing a reader signal.

Fig. 3 shows an embodiment of an active tag which comprises a non-linear ear reinforcement element. The tag 30 comprises an antenna 31 connected to a bandpass filter 32, which may be a coil connected in series with a capacitor. An amplifier 33 is connected across the bandpass filter. The amplifier 33 may be a threshold amplifier, where the signal must be above a specific threshold value to be amplified. When the signal from the antenna 31 is above said threshold value, after filtering the filter 32, the signal is amplified by the amplifier 33 and fed back to the input of the filter 32 as a larger signal. The amplifier is connected with positive feedback and the amplifier 33 will come into oscillation within a short period of time, called a latency period. The oscillations generate a signal emitted by the antenna 31. The reader 11 can sense this emitted signal in response. The signal generated by the amplifier 33 is also output at an output 38 via a diode 37 or nansistor to a control circuit of the tag 30. At the same time, the output signal controls a switch 34 in the feedback loop of the amplifier 33 via a control line 35. When the oscillating signal is large enough , the switch 34 is opened and connects a resistor 36 in the feedback loop, which causes the oscillations to cease. Thus, the tag 30 according to sufficient signal strength. This oscillating signal continues until it is interrupted by the switch 34. Thus, the reader ll can send a signal for a short period of time and then listen for signals with the same or similar fi-sequence. If such a signal is sensed after the reader signal has ceased, this is an indication that a tag 30, which may respond to substantially the same frequency, is present within the range of the reader 11.

Fig. 5 is a more detailed circuit diagram of a voltage dependent amplifier 60, an amplifier. The amplifier includes a FET nansistor 61, four coils 62, 63, 64, 65, two variable capacitors 66, 67, two insulating capacitors 68, 69. and a resistor 70 coupled ßr to form an oscillator. A positive supply voltage is connected to a voltage connector 71 at one end of the coil 63. A source of voltage 72 is connected to the gate of the transistor 61 via the resistor 70 and the coil 62. An antenna signal is connected to an antimic socket 73. A diode 74 or transistor provides an output signal at an output contact 75 to a control circuit 76. A reset switch 77 is controlled by the control circuit via a control line 78.

The circuit is essentially a modified Colpitt oscillator circuit, but other known circuit diagrams may be used as well, such as the Hartley oscillator, Armstrong oscillator, or Vackar oscillator.

During normal operation, without any input signal at the antenna connector 73, the resistor 70 and the voltage source 72 maintain the gate of the F ET coil resistor 61 during a knee voltage ring of the transistor and virtually no current passes through the transistor 61. The circuit is in an idle position or a meta-stable position , and draws virtually no power from the power source.

Transistor 61 is at a position 79 on a dry gain curve shown in fi g 7, where the dry gain is below “one”. This is called the first operating state, which occurs in a sub-threshold region of the operating diagram on the transistor. In this range, the power or current consumption of the transistor is very low and the gain of the transistor is also low or less than "e".

However, if a signal appears on the antenna connector 73 with an amplitude or power sufficient to pass the transistor across the knee voltage indicated by line 79 and into the range where the gain is above the "one", the transistor 61 will begin to draw current. The circuit then waves to oscillate at the frequency determined by the coil 65 and the capacitors 66 and 67. The oscillations cause the circuit to enter the saturation orbital range indicated by line 80 in fi g 7. This is called the second operating state, where oscillations occur at a specific resonant frequency. . The circuit will have resonance for antenna signals selected by the circuit comprising the coil 65 and the capacitors 66, 67, tuned to a resonant frequency (fl). Such resonant signals will trigger transistor 61 and initiate oscillations.

An output signal from the transistor 61 is supplied to a control circuit 76, which is controlled by a switch 77 via a line 78 for resetting the circuit stone and for preventing further oscillations.

Thus, the circuit i fi g 5 operates in its first operating state in the sub-threshold range of the transistors 60, 61, whereby virtually no current connection takes place. Only when an antenna signal is received as described above, does the circuit start consuming power in the second operating state. Thus, the circuit is always actively listening for radio signals without consuming the power supply.

The circuit in fi g 5 can be said to have a meta-stable first operating state because the dry gain in the positive feedback loop is below “one”. Thus, the circuit can remain in the meta-stable first operating state for an indefinite period of time. Metastability in electronics is defined as the ability of an unbalanced electronic state to remain for a long and theoretically unlimited period of time.

When a signal above a certain amplitude or electricity is received, the circuit becomes unstable.

The gain increases to above “one” and the circuit begins to oscillate in the second tillståndmction state.

The circuit is transmitted to oscillating tones with rapidly increasing amplitude. However, this "transfer" may take some time, until the oscillators start, which is called a latency period. Thus, the response time of the circuit may be in the range of parts of or a few microseconds, until the circuit has begun to oscillate.

It is pointed out that an antenna signal with a utanför sequence outside the predetermined fi sequence range will trigger the circuit if it is close enough and has a sufficiently high signal strength.

Fig. 8 shows a diagram of the Q-value for the circuit in fi g 5. At the center frequency, the Q-value is for example “two” when the circuit is in the area with maximum gain for the circuit, ie in the operating range between lines 79 and 80 in fi g 7. Thus, at an excitation frequency fc, the circuit will begin to oscillate relatively quickly. However, if the excitation frequency is in the frequency band between fl and 12, the circuit will still start to oscillate (possibly with a longer latency period and a higher required input power), since the gain will be above “e”. However, once the oscillations have been initiated, the oscillation sequence will shift toward the center frequency fc. This property can be used and is referred to below as dissonance.

Assume that readers send a signal with a fl sequence fl, which is on the line for 3 dB in the response box 81 shown in fi g 8. In doing so, all tags with a frequency band that includes the lock fi sequence will begin to oscillate and send a signal. The transmitted signal will be the center frequency of the tag in question. Thus, when the reader transmits a signal having a frequency f1 with a frequency f1, as shown in Fig. 8, a tag with a fi-sequence response 81 in fig tag with a frequency response 82 according to fi g 8 will begin to oscillate omid-ing a F sequence F82.

The center frequency fc ßr a tag can be set fi- at the beginning or can be set, for example as shown in fi g 5. A variable capacitor or a variable inductance (coil) can be used to tune the circuit. A variable capacitor or varactor is well known and comprises a diode in which the width of the barrier layer between p-doped and n-doped regions is controlled by a gate voltage.

A variable inductance or capacitor can also be constructed using fl your switches to include one or fl your inductors or capacitors in the LC circuit.

The switches can be controlled during or before the function. For example, the LC circuit may be tuned to the reader frequency from the beginning and when a signal indicating oscillations is present at the output, another parallel capacitor may be connected in the circuit, whereby the oscillation frequency is shifted to a lower value (f82), or another series capacitor may be connected circuit, which shifts the oscillations to a higher value (f8 1).

Alternatively, the control circuit may set the LC circuit before operation to an expected reader transmission frequency. After receiving the reader signal and oscillations, the control circuit resets the oscillations. Then you can control the frequency of the reader.

The filter has been shown as an LC circuit comprising an inductance and two capacitors. However, any filter circuit can be used which has a resonant sequence, i.e. a bandpass filter. Such filters may include MEMS filters, a crystal filter, ceramic filters, LC filters with more than three components, active filters.

In one embodiment, the receiving circuit shown can be used only for "awakening" the tag. Such an embodiment is shown in Fig. 9. The device comprises an antenna 13. A bandpass filter 132 and a non-linear amplifier 133 are connected to form an oscillator, which begins to oscillate when the signal from the antenna is large enough to start the oscillations. A comparator senses the oscillations and controls a switch 135, which can switch on the power supply to the control circuit 136. The control circuit sends a signal to the oscillator to deactivate the oscillations by opening a switch 137, thereby including a resistor 138 in the oscillating circuit, thereby oscillating. At the same time, the control circuit connects another switch 139 to the power supply for the control circuit. The control circuit 136 includes another transceiver 140 according to some known principle, such as a heterodyne receiver, which takes over the continued function of the tag. The transceiver is connected to the antenna 131. When the function has been completed according to some algorithm, the control circuit deactivates itself by opening the switch 139 (the switch 138 is open), and the tag returns to the first operating state and waits for a new wake-up signal at the predetermined frequency. 10 15 20 25 30 35 EEE fl- OPEN 9 The reader can send a 'single frequency' signal or a broadband wake-up signal that includes fl era fi sequences or a band of frequencies, such as a "Dirac" pulse. The tags that receive a signal at the predetermined frequency with sufficient signal strength will wake up. In this way, the tag will be in its low state for a long time, until a wake-up signal is received. If a temporary wake-up signal is received, the tag will only wake up for a very short period of time, until the control circuit has verified that the wake-up signal was not a valid wake-up signal given by a reader.

The sensitivity of the receiver circuit can be adjusted so that a suitable compromise is obtained between a safe function and too many unintentional wake-up signals. This is obtained by setting the bias voltage of the transistor to be closer or farther from the trigger point where self-oscillations start.

The circuit in fi g 5 comprises a bias circuit comprising a voltage source 71 which is connected to the gate of the transistor 61. By setting the voltage source 72 and the resistor 70, a suitable sensitivity can be obtained, i.e. a suitable distance therefrom.

In one embodiment, the receiver circuit includes means for adjusting the sensitivity of the receiver circuit. The voltage source 72, which is connected to the gate of the transistor 61, may be adjustable. A circuit for obtaining such a variable bias voltage is shown in fi g 6. In the series circuit consisting of the resistor 70 and the voltage source 72 a normally open switch 188 is arranged. A resistor 189 is connected in parallel with the voltage source and the switch 188 as shown in Fig. 6. If the switch 188 is open, the gate of the transistor 61 will be connected to ground via the resistors 70 and 189. Thus, Vin is substantially zero and the receiver circuit indicates its origin in the diagram. according to fi g 7. Transistor 61 is mainly blocked and the receiver circuit is in a first low-sensitivity state.

If the switch 188 is closed, the function point will be moved to the right in fi g 7 closer to the line 79, the receiver circuit being in a second high-sensitivity state. In the first low-sensitivity state, a large signal on the input contact 73 is required to trigger the circuit. . If such a large signal is received, the circuit is triggered and the control circuit 76 may be arranged to close the switch 188, the receiver circuit being transmitted to the second high sensitivity state.

Such activation of the recipient can take place when the item or product that carries the recipient circle or tag is transferred from an intermediate warehouse to a store, where the product is exposed for sale. The intermediate storage or a transport device may comprise a strong transmitter, which is used for activating the receiving circuit to a more sensitive state.

Activation can take place in another way, such as with ultrasound, illumination, light, laser or radioactive radiation. 10 15 20 25 30 35 532 ÃÅIB 10 The switch 188 may be a spring-loaded switch held open by a combustible material. When the combustible material is affected, for example by ultrasound or IR light, it can melt and the switch to be moved to the closed position.

Other devices for activating the receiving device are also possible.

Radioactive radiation, such as gamma, beta or alpha radiation, can be used to actuate switch 188 to close the switch.

The receiver circuit can have fl your sensitivity states, for example three states with low, medium and high sensitivity.

The sensitivity can be continuously adjustable.

For example, the receiver circuit may have a very low sensitivity from the beginning and be subjected to high energy activation, for example after leaving an intermediate layer, as described above. At the same time, a clock circuit can be started which increases the sensitivity further after a predetermined time, for example three days, corresponding to the expected time from the intermediate warehouse to the store.

If the goods leaving the intermediate layer are to pass a second intermediate layer of smaller size, the watch may increase the sensitivity from the first low-sensitivity state, to a second intermediate state, after, for example, three days, and then to a third high-sensitivity state. condition after fourteen days, when the goods are expected to be in the store The adjustable sensitivity feature can be used with any of the other embodiments of this specification.

Fig. 10 shows another embodiment where fl your circuits 142, 143 are connected to the same antenna 141. Each circuit comprises a deactivation switch 144 and 145 respectively. Two circuits are shown in fi g 10 but any number of circuits can be used. The first circuit 142 is tuned to the frequency f81 corresponding to a logic “e” and the second regenerative circuit 143 is tuned to the frequency F82 corresponding to a logic “zero”. A control circuit 146 controls the activation of the switches 144 and 145 of each circuit depending on a signal received by a sensor 147.

The function for sensing the tag is as follows. The reader has identified the tag in some way. The tag is sensed at a predetermined frequency, such as the frequency fl specified in fi g 8. The control circuit activates the switches 144 and 145 depending on the most significant bit of the sensor value 147, which may be an temperature sensor with an eight-bit value to be transmitted. to the reader. If the most significant bit is “one”, switch 144 is closed and switch 145 is opened, while if the most significant bit is “zero”, switch 145 is closed and switch 144 is opened.

If the most significant bit is "one", the oscillation circuit 142 will start oscillating at the frequency f81. If the most significant bit is "zero", the oscillation circuit 143 begins to oscillate at the frequency f82. The reader senses the answer. Then, the control circuit 10 deactivates the oscillations and controls the switches 144 and 145 according to the next bit in the signal and the reader transmits a second sensing signal at the frequency f1 and so on. After eight sensing signals, eight bits of the temperature signal have been sent to the reader.

The same principle can be used with a single circuit, where the control circuit controls a varactor or similar device depending on the sensor signal.

If it is possible that certain frequency ranges are occupied by other transmitters, the electronic device according to one of the above embodiments may comprise devices for avoiding such frequency domains, for example under the control of a reader.

The device according to any of the embodiments described above may be manufactured in a CMOS technology. However, other technologies can be used, such as discrete components, such as MOSFET transistors, with a very low power consumption in the low power state.

Fig. 11 is a circuit diagram of another embodiment of the oscillation circuit. The circuit is similar to the circuit shown in fi g 5, but is arranged in a balanced way. The circuit needs only a single inductor, which makes it suitable for operation on a silicon wafer with all the components on the wafer.

The oscillation circuit comprises a first NFET transistor 151 and a second PFET transistor 152. An inductance 153 is connected between the sources of the transistors. In parallel with the inductor, three capacitors 154, 155, 156 are connected to each other in series. The gates of the transistors are supplied with a gate voltage via two voltage sources 157, 158 and two resistors 159, 160 so that the transistors are normally located in an area below the normal operating range of the transistor, in a sub-threshold range. The gates of the transistors are connected to an antenna contact 161 via a balun 162 which converts the unbalanced antenna signal to a balanced signal and via two isolation capacitors 163, 164, 165, 166 each. 168 and an output capacitor 169. A control line 171 controls two reset switches 172 and 173. The function is similar to the circuit in fi g 5.

The circuit works as a combination of a bistable and an unstable multivibrator. In the first operating state, the circuit is meta-stable, which means that a trigger signal with sufficient power in the relevant frequency band will transmit the circuit to the second operating state. In the second tillståndmction state, the circuit acts as an unstable multivibrator and oscillates at a specific frequency. The oscillations continue until some external event stops the oscillations and returns the circuit to the first meta-stable state.

The balanced receiver circuit according to fi g 11 may include the possibility to change the sensitivity as shown in fi g 12. Other ways of setting the sensitivity or setting the operating point of the transistors 151, 152 may be possible for a person skilled in the art.

Fig. 12 shows a circuit according to fi g ll with another bias circuit comprising three resistors 174, 175, 176 connected in series from the positive contact to the gate of the first transistor 53.2 ÅÅB 12 transistor, from the gate of the first transistor to the gate of the second transistor and fi from the gate of the second transistor to the negative contact. By means of these resistors 174, 175, 176, the circuit is biased to a first sensitivity state with low sensitivity, since the resistor 175 is smaller than the resistors 174, 176. By means of two switches 178, 180, second resistors 177, 179 can be connected in parallel with resistors 174, 176 so that the parallel-connected resistors change the bias point of the circuit to a second more sensitive state. A single switch 190 connects the gates of the two transistors to stop the oscillations and form another even less sensitive state compared to the first sensitization state.

Fig. 13 shows a conventional oscillator circuit, where the oscillations are controlled by a current source. As in the circuit of Fig. 11, the antemis signal is supplied to the gates of the transistors via a balun and two capacitors.

However, the oscillator circuit can be made using bipolar transistors.

The sensitivity can be set by setting the base current, for example by connecting mot your resistors in series or in parallel by means of one or fl your switches.

Unless otherwise defined, all terms (including technical and scientific terms) have the same meaning as those understood by one of ordinary skill in the art to which this invention belongs. It is further noted that terms, such as those as they are included in commonly used dictionaries, should be construed as meaning that they are consistent with their meaning in relation to relevant technology and should not be interpreted in an idealized or overly formal way, unless they have the expression they fi nierats so here.

It should also be noted that the singular form "en", "ett", "den", "det", as used herein, is intended to include the plural forms as well, unless expressly stated otherwise. It is further noted that the term "includes", when used in the specification, is to be construed as specifying the presence of the indicated wound feature, integer, steps, functions, elements, and / or components, but does not exclude the presence of one or more of its additional features. integers, steps, functions, elements, components and / or groups.

The present invention has been described above with reference to specific embodiments. However, embodiments other than those described above are equally possible within the scope of the invention. Different procedure steps than those described above, performing the procedure with hardware or software or a combination of hardware and software can be performed according to the invention. The various features and steps of the invention can be combined in other combinations than those described. The various embodiments described above do not limit the invention, but the scope of the invention is limited only by the appended claims.

Claims (7)

10 15 20 25 30 35 ESQ 443 13 CLAIMS A method of operating an electronic device equipped with a receiver for receiving signals transmitted by transmitters; characteristics! by first operating the electronic device (60) in a metastable first operating state; operating the electronic device in a second oscillating mode of operation, the electronic device (60) oscillating at a predetermined oscillation frequency; transmitting the electronic device from said first till state of action to said second still state of action by means of a bias circuit (70, '72, 188, 189), which is triggered by a wirelessly transmitted signal, which has a predetermined signal vens sequence and power level and which is received by an antenna of said electronic devices; terminating said second operating state and transferring the device to said metastable first operating state by means of an extinguishing circuit (77); said bias circuit comprising a first sensitivity state, wherein the bias circuit (70, 188, 189) has a first sensitivity and a second probability state where the bias circuit (70, 72, 188) has a second sensitivity greater than the first sensitivity; and transmitting the bias circuit from the first probability state to the second sensitivity state by receiving a wirelessly transmitted signal. The method of claim 1, wherein said wirelessly transmitted signal is an electromagnetic signal received by said antenna. The method of claim 1, wherein said wirelessly transmitted signal is an infrared signal, a laser signal, a radioactive signal or an ultrasonic signal. An electronic device provided with a receiver (60) for receiving a first signal with a first frequency transmitted by a transmitter; characterized by an oscillation circuit (60) biased for imction in an inactive, metastable first ktction state and intended to operate in a second oscillating state of operation, where the oscillation unit oscillates at a predetermined oscillation ven equation (70), transmitting the oscillation circuit from said first operating state to said second operating state by triggering with a signal having a predetermined signal frequency and power level and received by an antenna of said electronic device; 53.2 443 14 an extinguishing layer (77) for terminating said second operating state and transferring the device to said first metastable operating state; said voltage circuit comprising a first sensitivity state, wherein the voltage circuit (70, 188, 189) has a first sensitivity and a second sensitivity state where the voltage circuit (70, 72, 188) has a second sensitivity which is greater than the first sensitivity; and a transmission circuit (188) for transmitting the voltage circuit from the first sensitivity state to the second sensitivity state upon receipt of a wireless transmitted signal. The device of claim 4, wherein said wirelessly transmitted signal is an electromagnetic signal received by said antenna. The device of claim 4, wherein said wirelessly transmitted signal is an infrared signal, a laser signal, a radioactive signal or an ultrasonic signal, An apparatus according to any one of claims 4 to 6, wherein the oscillation circuit comprises an amplifier element (61) and an filter element (65, 66, 67) connected to form an oscillating circuit.