Abstract: In the method for the transfer of a digital data signal with predetermined band width from a transmitter to a receiver, the spread spectrum technique is used. In the method, the data signal is modulo-2 added with a PN code sequence, the bit rate of which is very much higher than the bit rate of the data signal. A carrier is then modulated with the resulting spread signal, after which the carrier is transmitted. The modulated carrier is demodulated in a receiver and the demodulated signal, to obtain the data signal, is multiplied with the PN code sequence produced in the receiver, synchronized with the PN code sequence of the transmitter by autocorrelation. A periodic rectangular signal with a constant duty cycle is used as code sequence.

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.

Abstract: In the transferring of a digital data signal from a transmitter to a receiver using the spread spectrum technique, the data signal is modulo-2 added with a PN code sequence, the bit rate of which is very much higher than the bit rate of the data signal. A carrier is then modulated and transmitted with the thereby resulting spread data signal. In the receiver, the modulated carrier is demodulated and the demodulated signal, to obtain the digital data signal, is multiplied with a PN code sequence produced in the receiver, coinciding and synchronized with the PN code sequence of the transmitter. In the transmitter, the carrier is modulated by FSK- or BPSK-modulation with the spread data signal. In addition, modulation is carried out by means of the respectively other of these two modulation types with a synchronizing signal representing the synchronizing information of the the PN code sequence.

Abstract: A transponder unit (10) includes an N cycle counter (30) and an M cycle counter (28). The N cycle counter (30) has a different cycle value than the M cycle counter (28). During the transmission of information from the transponder unit (10), the duration for data bits having a binary zero value is controlled by the N cycle counter (30). The duration of data bits having a binary one value is controlled by the M cycle counter (28). The use of different cycle values within the N cycle counter (30) and the M cycle counter (28) allows for the transmission of binary one and binary zero data bits having the same bit length despite different frequencies representing the binary one and binary zero bits respectively.

Abstract: A transponder device (10) includes a discharge circuit (18) to control the discharge of voltage from a charge capacitor (14). The discharge circuit (18) prevents transmission of a data telegram by the transponder device (10) until a voltage of the charge capacitor (14) reaches a threshold voltage level. The threshold voltage level is sufficient to ensure that a complete transmission of the data telegram is performed. Upon reaching the threshold voltage level, a transponder analog and digital circuit (19) initiates transmission of the data telegram. A control logic circuit (32) activates a counter (36) upon the start of the data telegram transmission. The counter (36) generates a control signal that is used to bypass the discharge circuit in order that the charge capacitor (14) can be connected directly to the transponder analog and digital circuit (19).

Abstract: An integrated vehicle communications system for on-board use within a vehicle which may also communicate with external portions of the system which includes miniaturized, self-contained read/write transponders 20, 22, 30 of the type disclosed in Schuermann U.S. Pat. No. 5,053,774, for providing functions within the vehicle, e.g., for sensing conditions and parameters, The on-board interrogation unit 10 interrogates and receives signals by RF communication provided by on-board antennas 14, 26, 28 between the interrogation unit and respective transponders for read/write responder operation. The processor 33 with display device 34a and/or control circuits 34b carries out on-board functions in response to such interrogation.

Abstract: A method for interrogating remote transponders having the steps of: sending an RF interrogation pulse from an interrogator (10), receiving by a first and second transponder (12,12a) the RF interrogation pulse, and establishing in a resonant circuit (130) of each of the transponders (12,12a) an oscillation, the oscillation being established by the coupling of signal energy from the RF interrogation pulse into the resonant circuit (130). After the RF interrogation pulse ends, the first transponder (12) senses the termination of the pulse and initiates a first RF response having a selected duration. A second RF response from the second transponder (12a) will also be detected in the first transponder (12) whose response will be affected by this second RF response.

Abstract: In a method for transmitting a data message comprising a synchronization section and a data section stored in a transponder device (10) to an interrogating device (12) in full duplex mode. The interrogating device (12) continuously emits an interrogating command, the receipt of which in the transponder device (10) prompts output of the data message. Both the sync section and the data section of the data message each comprise a predetermined number of bits in accordance with a given transmission protocol. In the sync section, a predetermined number N of sequential bits of duration .tau. is replaced by a lesser number n of sequential bits of longer duration T, where: T=.tau. N/n. The interrogating device (12) determines the location of the sync section and thus the start of the data section in the received data message by identifying the bits having the longer duration T. For the ratio N/n a value is selected which is smaller than 1.5.

Abstract: A method is disclosed herein for tuning a responder unit (12). The method comprises the stops of storing energy in a responder unit energy accumulator (136) in a contactless fashion by RF energy transmitted from the interrogator unit (10) to the responder unit (12), and exciting within the responder unit (12) an RF carrier wave. The method further comprises the stops of transmitting the RF carrier wave in a first response from the responder unit (12) to the interrogator unit (10) and measuring within the interrogator unit (10) the received signal strength of the RF carrier wave of the first response. In further accordance with the invention tuning data may be transmitted to the responder unit (12) by sending at least one RF programming sequence from the interrogator unit (10) to the responder unit (12).

Abstract: An transponder arrangement (10) for use with tires (20) is described. The arrangement (10) includes an antenna (14) which is mounted about the tire's (20) perimeter. The antenna (14) preferably has a coupling coil (16) at one end. A transponder (12) is preferably located close to the coupling coil (16) and is preferably loosely coupled to the coupling coil (16). The RF-ID efficiency of the arrangement (10) is generally optimized for this type of application by the long but narrow antenna solution and by the simple fact that coupling an antenna (14) to a transponder (12) amplifies the emission of the transponder's signal relative to the noise, thus improving the signal-to-noise ratio of the RF-ID system. The degree of coupling between the antenna (14) and the transponder (12) is not particularly critical. The antenna (14) acts to extend the reading range for the interrogator (24) to be generally, radially symmetric about the tire (20). Other arrangements are disclosed.

Abstract: A method for interrogating remote transponders having the steps of: sending an RF interrogation pulse from an interrogator (10), receiving by a first and second transponder (12,12a) the RF interrogation pulse, and establishing in a resonant circuit (130) of each of the transponders (12,12a) an oscillation, the oscillation being established by the coupling of signal energy from the RF interrogation pulse into the resonant circuit (130). After the RF interrogation pulse ends, the first transponder (12) senses the termination of the pulse and initiates a first RF response having a selected duration. A second RF response from the second transponder (12a) will also be detected in the first transponder (12) whose response will be affected by this second RF response.

Abstract: A transponder system comprises an interrogation unit for communicating with a plurality of responder units. At least one responder unit receives an interrogation signal from the interrogation unit and returns data as signal information to the interrogation unit in response to the reception of the interrogation signal. The responder unit also includes sensor circuitry sensitive to predetermined physical parameters in the environmental area of the responder unit and, via a data processor, generates data representative of the physical parameter and sends it back to the interrogator as signal information.

Abstract: An interrogation unit which has a control circuit and an RF oscillator is described. The interrogation unit further has a transmitter which receives the output of the RF oscillator and transmits at least one RF interrogation pulse of a first frequency for interrogating the responder unit, causing the responder unit to return read data in the form of a RF response. Also in the interrogation unit is a switch for disabling the output of said transmitter and enabling reception of the RF response upon termination of the RF interrogation signal. The interrogation unit still further has a receiver for receiving the RF response upon termination of the RF interrogation pulse and an interrogation unit demodulator for demodulation of the read data from said RF response.

Abstract: A responder unit for communicating with an interrogator unit which sends an RF interrogation pulse thereto is described. The responder unit includes an energy accumulator which stores the energy contained in the RF interrogation pulse to be used to power the responder unit in the absence of any RF interrogation signal. The responder unit also has a memory for storing read data and a RF threshold detector for detecting termination of the RF interrogation pulse. A RF carrier wave generator under control of the RF threshold detector is operable to activate upon detection of the termination of the RF interrogation pulse. A modulator is provided in the responder unit to modulate the RF carrier with the read data from the memory.

Abstract: A method is disclosed herein for tuning a responder unit (12). The method comprises the steps of storing energy in a responder unit energy accumulator (136) in a contactless fashion by RF energy transmitted from the interrogator unit (10) to the responder unit (12), and exciting within the responder unit (12) an RF carrier wave. The method further comprises the steps of transmitting the RF carrier wave in a first response from the responder unit (12) to the interrogator unit (10) and measuring within the interrogator unit (10) the received signal strength of the RF carrier wave of the first response. In further accordance with the invention tuning data may be transmitted to the responder unit (12) by sending at least one RF programming sequence from the interrogator unit (10) to the responder unit (12).

Abstract: A transponder (14) for communicating with an interrogator (12) has a high Q-factor resonant circuit (34) of frequency f.sub.1 for receiving RF powering signals. The transponder also has a tuning circuit (56,58) which when in electrical communication with the resonant circuit (34) is operable to form a lower Q-factor resonant circuit (60) of frequency f.sub.3 for receiving RF communications from the interrogator unit. The transponder also includes a demodulator (66) which is in electrical communication with said resonant circuit (34). Additionally, the transponder (14) also included a control circuit (40) which receives a demodulated data signal from the demodulator (66). The control circuit (40) is further connected to the tuning circuit (56,58) and is operable to connect the tuning circuit (56,58) to the high Q-factor resonant circuit (34) in order to form the lower Q-factor resonant circuit (60). Control circuit (40) also converts the RF powering signals to a DC current for storing energy.

Abstract: A method of communicating between a transponder and an interrogator. The interrogator (10) transmits a wireless RF interrogation which is received by the transponder (12). The transponder (12) then transmits a wireless RF response. The wireless RF response has a first channel response centered at frequency FDX1=RF+SC, a second channel response centered at frequency FDX2=RF-SC, and a third channel response centered at frequency FDX3=SC. The third channel response is a spurious signal resulting from using a non-linear element (32) as the transponder modulator (32,34). The interrogator (10) receives this wireless RF response. The response is received in the three channels with a first circuit (82) operable to receive said first channel response, a second circuit (86) is operable to receive said second channel response, and a third circuit (86,88) is operable to receive said third channel response.

Abstract: A transponder (14) for communicating with an interrogator (12) has a high Q-factor resonant circuit (34) of frequency f.sub.1 for receiving RF powering signals. The transponder also has a tuning circuit (56,58) which when in electrical communication with the resonant circuit (34) is operable to form a lower Q-factor resonant circuit (60) of frequency f.sub.3 for receiving RF communications from the interrogator unit. The transponder also includes a demodulator (66) which is in electrical communication with said resonant circuit (34). Additionally, the transponder (14) also included a control circuit (40) which receives a demodulated data signal from the demodulator (66). The control circuit (40) is further connected to the tuning circuit (56,58) and is operable to connect the tuning circuit (56,58) to the high Q-factor resonant circuit (34) in order to form the lower Q-factor resonant circuit (60). Control circuit (40) also converts the RF powering signals to a DC current for storing energy.

Abstract: A novel antenna system disposed around a conveyor belt for the interrogation of objects passing through the antenna which overcomes centralized dead zone problems is disclosed. A frame antenna is disposed around a conveyor belt and is tilted to form, for example, a 30 deg. angle with the vertical longitudinal plane of the conveyor belt, which is perpendicular to the horizontal plane within which the conveyor belt lies, and a 30 deg. angle with the transverse axis of the conveyor belt. In this way, a "dead-zone" free read area is formed to facilitate the read of a transponder oriented in any manner as it moves along the conveyor belt.

Abstract: A transponder arrangement is described comprising an interrogation unit (10) which sends an RF interrogation pulse to at least one responder unit (12). The responder unit (12) then transmits back data stored therein in the form of a modulated RF carrier to the interrogation unit (10). In the responder unit (12) is an energy accumulator (136) which stores the energy contained in the RF interrogation pulse. The responder unit (12) further contains means (142, 148) which in dependence upon the termination of the reception of the RF interrogation pulse and the presence of a predetermined energy amount in the energy accumulator (126) initiate the excitation of an RF carrier wave generator (130, 132, 134) operating with the frequency contained in the RF interrogation pulse.