Method and circuit of an actively transmitting tag
First Claim
1. A method for high-frequency communication between an interrogator and an actively transmitting tag, which, before it starts transmitting a data frame, first observes a phase of an antenna signal due to an interrogator'"'"'s radiation field and then starts transmitting the data frame in the form of a sequence of high-frequency bursts by exciting, through a matching circuit, its own antenna with a transmitted signal initially having said observed phase of the antenna signal, wherein the actively transmitting tag transmits the data frame by transmitting the high-frequency bursts, each of them having a length of one subcarrier half-period of the transmitted signal and their phase being inverted according to a communication protocol each time at the end of the subcarrier half-period, wherein, in time intervals with the length of one subcarrier half-period during transmitting the data frame, the actively transmitting tag detects a shift of the phase of the antenna signal with regard to a phase of the transmitted signal, and wherein each time after transition into a subsequent subcarrier half-period, the actively transmitting tag controls generating the high-frequency burst according to said detected shift of the phase.
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Abstract
An actively transmitting tag detects a shift of a phase of an antenna signal (as) with regard to a phase of a transmitted signal (ts) in time intervals with a length of one half-period of a subcarrier, in which time intervals it transmits high-frequency wave packets with their phase being inverted according to a communication protocol at the ends of said half-periods. Generation of said wave packets is controlled by said phase shift in a way that said phase shift retains its absolute value at transitions into subsequent half-periods. Synchronizing the tag'"'"'s transmission to a received interrogator signal carried out even during tag'"'"'s transmitting enables the tag to transmit according to protocol ISO 14443 B by inverting a phase at transitions between said half-periods. Said synchronizing is carried out although no time window without a tag transmitting exists within the transmitted data frame.
9 Citations
34 Claims
- 1. A method for high-frequency communication between an interrogator and an actively transmitting tag, which, before it starts transmitting a data frame, first observes a phase of an antenna signal due to an interrogator'"'"'s radiation field and then starts transmitting the data frame in the form of a sequence of high-frequency bursts by exciting, through a matching circuit, its own antenna with a transmitted signal initially having said observed phase of the antenna signal, wherein the actively transmitting tag transmits the data frame by transmitting the high-frequency bursts, each of them having a length of one subcarrier half-period of the transmitted signal and their phase being inverted according to a communication protocol each time at the end of the subcarrier half-period, wherein, in time intervals with the length of one subcarrier half-period during transmitting the data frame, the actively transmitting tag detects a shift of the phase of the antenna signal with regard to a phase of the transmitted signal, and wherein each time after transition into a subsequent subcarrier half-period, the actively transmitting tag controls generating the high-frequency burst according to said detected shift of the phase.
- 9. A circuit for high-frequency communication between an interrogator and an actively transmitting tag, whose antenna signal (as) is conducted from an antenna into a digitizer, whose output is connected to an input of a phase-frequency comparator, which, before the actively transmitting tag starts transmitting a data frame, first observes a phase of the antenna signal due to an interrogator'"'"'s radiation field in order that the actively transmitting tag starts transmitting the data frame in the form of a sequence of high-frequency bursts in a way that a voltage-controlled oscillator starts generating a transmitted signal initially having said observed phase of the antenna signal and in the form of said high-frequency bursts being conducted to the antenna through an output amplifier and a matching circuit, wherein the actively transmitting tag transmits the data frame by transmitting the high-frequency bursts each of them having a length of one subcarrier half-period of the transmitted signal and their phase being always inverted according to a communication protocol at the end of the subcarrier half-period, wherein an output of the digitizer and an output of the output amplifier are connected to input terminals of a phase-displacement detector, which, in time intervals with said length of one subcarrier half-period, detects a shift of the phase of the antenna signal with regard to a phase of the transmitted signal, and wherein a phase-displacement signal from an output of the phase-displacement detector is conducted to a regulator circuit, which, while the high-frequency bursts are transmitted, controls the voltage-controlled oscillator in order to generate the high-frequency bursts according to said detected shift of the phase.
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17. A method for high-frequency communication between an interrogator and an actively transmitting tag, the method comprising:
- determining, by the actively transmitting tag and prior to transmitting a data frame, a phase of an antenna signal due to a radiation field of the interrogator;
exciting, through a matching circuit, an antenna of the actively transmitting tag with a transmitted signal, wherein the transmitted signal initially has a phase equal to the phase of the antenna signal;
generating, by the actively transmitting tag, a sequence of high-frequency bursts corresponding with the data frame;
transmitting, by the actively transmitting tag, the sequence of high-frequency bursts, wherein each high-frequency burst has a length of one subcarrier half-period of the transmitted signal and a phase inverted according to a communication protocol at an end of each subcarrier half-period;
detecting, by the actively transmitting tag and during the transmitting of the data frame, a shift of the phase of the antenna signal relative to a phase of the transmitted signal in time intervals with a length of one subcarrier half-period; and
controlling, by the actively transmitting tag, the generating of the sequence of high-frequency bursts according to the shift of the phase of the antenna signal after each transition into a subsequent subcarrier half-period. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
- determining, by the actively transmitting tag and prior to transmitting a data frame, a phase of an antenna signal due to a radiation field of the interrogator;
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25. A circuit for high-frequency communication between an interrogator and an actively transmitting tag, the circuit comprising:
- an antenna configured to receive an antenna signal;
a digitizer comprising an input coupled to the antenna;
a phase-frequency comparator configured to determine a phase of the antenna signal due to a radiation field of the interrogator prior to transmitting a data frame, wherein an input of the phase-frequency comparator is connected to an output of the digitizer;
a voltage-controlled oscillator (VCO) configured to generate a transmitted signal that initially has a phase equal to the phase of the antenna signal, wherein the transmitted signal is a sequence of high-frequency bursts corresponding with the data frame, and wherein each high-frequency burst has a length of one subcarrier half-period of the transmitted signal and a phase that is inverted according to a communication protocol at an end of each subcarrier half-period;
an output amplifier and a matching circuit configured to conduct the transmitted signal to the antenna;
a phase-displacement detector configured, in time intervals with the length of one subcarrier half-period, to detect a shift of the phase of the antenna signal relative to a phase of the transmitted signal, and wherein an output of the digitizer and an output of the output amplifier are connected to input terminals of the phase-displacement detector; and
a regulator configured, during the transmission of the sequence of high-frequency bursts, to control the VCO to generate the sequence of high-frequency bursts according to the shift of the phase of the antenna signal, wherein an output of the phase-displacement detector is conducted to an input of the regulator. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
- an antenna configured to receive an antenna signal;
Specification