Abstract:
A passive entry and immobilizer key for vehicles comprises an integrated front-end circuit (12b) with three battery-supplied receiver channels (14, 16, 18), each connected to an associated external antenna circuit with an inductor-capacitor combination (LR, CR) having a resonant frequency in the very low frequency range. The three antennas are arranged in a three-dimensional configuration. An immobilizer transponder (22) is supplied by energy received from an external transponder antenna circuit and stored in a storage capacitor (CL). The transponder antenna circuit includes an inductor-capacitor combination (LR, CR, CL) having a resonant frequency in the low frequency range. The transponder antenna circuit shares at least one inductive component (LR) with the antenna circuit of one of the three receiver channels. A capacitor in the transponder antenna circuit is selectively disconnected to change the resonant frequency from a frequency in the very low frequency range to a frequency in the low frequency range. Accordingly, one of the three antenna circuits has a dual function. A first function is that in a three-dimensional analog front end of a passive entry system that operates in the very low frequency range. A second function is that in a transponder of an immobilizer system that operates in the much higher low frequency range. As a result, only three antenna coils need to be implemented in the key.
Abstract:
Transponders present in an interrogation zone can be identified by an interrogator by it sending an RF interrogation signal into the interrogation zone, the RF interrogation signal containing a code string prompting the transponders to generate partial addresses. As soon as one transponder “sees” that the generated partial address agrees with part of its own address, it responds by sending its full address which can then be read by the interrogator. Immediately after having received a full address the interrogator sends a code string characterizing the address of the transponder having responded before so that this transponder is thereby addressable. The signal sent by the interrogator to the transponder with this code string also contains an instruction which prompts the transponder to assume the condition in which it no longer responds to receiving its address or partial address.
Abstract:
For reading the data stored in a transponder by means of an interrogation device, the interrogation device at first receives the background noise for the purpose of detecting interference frequencies present in this background noise. On the basis of the interference frequencies acquired, coefficients for an adaptive filter are computed by means of which this filter may be tuned in such a way as to suppress the interference frequencies. The response signal from the transponder with the superimposed background noise is received by the interrogation device and routed through the adaptive filter which acts to suppress the interference frequencies. The signal available at the output of the filter can then be demodulated for the purpose of reading the data stored. The transponder system for the execution of the procedure comprises a digital signal processor which computes coefficients for an adaptive filter on the basis of the interference frequencies acquired, and tunes the filter in such a way that the interference frequencies within the RF response signal received from the transponder, carrying the superimposed background noise, are suppressed. The output signal from the adaptive filter may then be used for further processing.
Abstract:
An electronic device and method for half duplex data transmission in a long range keyless entry and go system, and more specifically to an RFID transponder, a corresponding read/write (R/W) unit and methods for operating the RFID transponder and the R/W-unit. There is a first coil, a second coil and a third coil, being arranged as a three-dimensional antenna, a first capacitor, a second capacitor and a third capacitor couplable in parallel to the first coil, the second coil and the third coil, respectively, for selectively forming a first, a second and a third parallel-resonant circuit for receiving radio signals, a series-resonant circuit for transmitting radio signals and a control stage configured to either use one of the first, second or third parallel-resonant circuits for receiving radio signals or the series-resonant circuit for transmitting signals.
Abstract:
A passive entry and immobilizer key for vehicles comprises an integrated front-end circuit (12b) with three battery-supplied receiver channels (14, 16, 18), each connected to an associated external antenna circuit with an inductor-capacitor combination (LR, CR) having a resonant frequency in the very low frequency range. The three antennas are arranged in a three-dimensional configuration. An immobilizer transponder (22) is supplied by energy received from an external transponder antenna circuit and stored in a storage capacitor (CL). The transponder antenna circuit includes an inductor-capacitor combination (LR, CR, CL) having a resonant frequency in the low frequency range. The transponder antenna circuit shares at least one inductive component (LR) with the antenna circuit of one of the three receiver channels. A capacitor in the transponder antenna circuit is selectively disconnected to change the resonant frequency from a frequency in the very low frequency range to a frequency in the low frequency range. Accordingly, one of the three antenna circuits has a dual function. A first function is that in a three-dimensional analog front end of a passive entry system that operates in the very low frequency range. A second function is that in a transponder of an immobilizer system that operates in the much higher low frequency range. As a result, only three antenna coils need to be implemented in the key.
Abstract:
A vehicular tire pressure monitoring system, including a transponder unit (10) for each tire to be monitored, the transponder unit having an incorporated RF transmitter (12) and being physically associated with the tire to be monitored. A pressure sensor for each tire to be monitored is connected to circuitry in a corresponding transponder unit. An interrogator unit (7) is associated with each transponder unit and physically mounted on a vehicle in proximity to a wheel (9) whereon a tire to be monitored is mounted. A central RF receiver (4) for all transponder units is provided. Each transponder unit is inductively coupled with an associated interrogator unit and includes an electric charge accumulation element adapted to be charged by energy inductively supplied from the associated interrogator unit in a first mode of operation, and the charge accumulation element providing a power supply to the RF transmitter of the transponder unit in a second mode of operation.
Abstract:
A method for the authentication of a transceiver unit with respect to a second transceiver unit, located at a distance to it. A first signal is transmitted via an aerial connected to the first unit, when second unit is located within the reception area of the first unit. The first signal is received by means of the second unit via an aerial connected to it, whereby, on the basis of the first signal received, a value is measured that characterizes the strength of the electro-magnetic field generated by the first signal at the location of the second unit. A second signal is transmitted via the aerial connected to the second unit that contains information relating to the magnitude characterizing the field strength; and the second signal is received via the aerial connected to the first unit, where, on the basis of the second signal received, a value is measured that characterizes the strength of the electro-magnetic field generated by the second signal at the location of the first unit. On the basis of the values characterizing the field strengths measured during the transmission of the first and the second signals, a comparison is made as to whether the two magnitudes of coupling corresponding to the field strengths between the two aerials coincide. Only when coincidence is established, a release signal is generated.
Abstract:
Transponder signal collision avoidance system incudes a reader and wireless HDX or FDX type transponders (A, B) are disclosed, interrogated by the reader (R) by alternately powering and then reading through cycles corresponding to a number of possible transponders in the interrogation field. The cycles, which include reader power pulses, signify addresses of respective possible transponders, whether in or out of the field. The transponders for this purpose count reader power pulses by end-of-burst detection, increasing a stored count value with each reader power pulse. The transponder responds to the reader by transmission if and only if a stored count value in a read cycle matches a respective transponder address, preventing the transponders from transmitting telegrams interfering with each other. As a method of reader-transponder operation, the collision avoidance scheme thus cycles the reader interrogating through cycles having power pulses according to possible transponders in the field, not only calling the addresses of each of respective possible transponders but also shortening or lengthening read and power steps dependent upon responses received from the transponders.
Abstract:
Apparatus and method for identifying a plurality of transponders (10-16) located within an inquiry field (18) of an interrogation unit (20) are provided. Each transponder (10-16) is assigned an unique identification code, and the interrogation unit (20) dynamically constructs and modifies a bit string used to solicit responses from selected transponder(s) until each transponder (10-16) in the inquiry field (18) is identified. The bit string is transmitted to the transponders, which compares it with the least significant bits of their respective identification codes. A mismatch between the identification code and the bit string results in suppressing the response from the transponder.
Abstract:
A half-duplex RFID transponder with an integrated three-dimensional front-end circuit which includes three LC resonant circuits arranged in a three-dimensional configuration. Each LC resonant circuit is coupled to a different one of three storage capacitors which are charged during a capacitor charging phase by energy in an RF signal received by the associated LC resonant circuit. The front-end circuit includes three receiver channels and each receiver channel is associated to a different one of the three LC resonant circuits. A channel selector is adapted to detect, which one of the three storage capacitors is first charged to a threshold voltage, to select the receiver channel associated to the LC resonant circuit which is coupled to the storage capacitor which is first charged and to deactivate the two other receiver channels. A method of operating a half-duplex RFID transponder with three LC resonant circuits arranged in a three-dimensional configuration with each LC resonant circuit coupled to a different storage capacitor which is charged during a capacitor charging phase by energy in an RF signal received by the associated LC resonant circuit. Three receiver channels are associated to the three LC resonant circuits. The method includes monitoring the charge level of each of the three storage capacitors, detecting which storage capacitor is first charged to a threshold voltage, selecting the receiver channel associated to the first charged storage capacitor and deactivating the two other receiver channels.