RFID tags calibrating backscattering period also for non-integer divide ratios
First Claim
1. A circuit for a radio frequency identification (RFID) tag, comprising:
- a demodulator that is arranged to demodulate a waveform of a wirelessly received wave;
a processing block that includes;
a counter configured to determine an L-number from a duration of a calibration feature of the waveform, and a combining circuit configured to combine a first nonzero version of the L-number with a second nonzero version of the L-number so as to derive a BP-number such that the derived BP-number substantially equals the L-number divided by a preset non-integer divide ratio; and
a modulator that is arranged to modulate a second wave with encoded symbols that have a periodicity determined from the BP-number.
1 Assignment
0 Petitions
Accused Products
Abstract
An RFID tag that receives a calibration instruction from a reader can determine the basic backscatter period of the symbols to be backscattered. According to some embodiments, when the instruction includes a calibration feature that is to be divided by a divide ratio, the tag measures the duration of the feature in terms of numbers of internal pulses, resulting in a binary L-number. Then at least two versions of the L-number (PR1-number, PR2-number) are combined, so as to yield the effective result of the division alternately, even when the divide ratio is a non-integer. The backscatter period can then be determined from the BP-number and the period of the internal pulses.
11 Citations
78 Claims
-
1. A circuit for a radio frequency identification (RFID) tag, comprising:
-
a demodulator that is arranged to demodulate a waveform of a wirelessly received wave;
a processing block that includes;
a counter configured to determine an L-number from a duration of a calibration feature of the waveform, and a combining circuit configured to combine a first nonzero version of the L-number with a second nonzero version of the L-number so as to derive a BP-number such that the derived BP-number substantially equals the L-number divided by a preset non-integer divide ratio; and
a modulator that is arranged to modulate a second wave with encoded symbols that have a periodicity determined from the BP-number. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
-
29. A radio frequency identification (RFID) tag, comprising:
-
an antenna arranged to receive a wireless wave;
a demodulator arranged to demodulate a waveform of the wirelessly received wave;
a processing block that includes;
a counter configured to determine an L-number from a duration of a calibration feature of the waveform, and a combining circuit configured to combine a first nonzero version of the L-number with a second nonzero version of the L-number so as to derive a BP-number such that the derived BP-number substantially equals the L-number divided by a preset non-integer divide ratio; and
a modulator that is arranged to backscatter via the antenna a wave with modulation that encodes symbols that have a periodicity determined from the BP-number. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
-
-
38. A circuit for a radio frequency identification (RFID) tag that is responsive to an RFID reader, the RFID tag comprising:
-
a means for demodulating a waveform from a first wireless wave received from the reader;
a means for determining an L-number from a duration of a calibration feature of the waveform;
a means for deriving a BP-number by combining a first nonzero version of the L-number with a second nonzero version of the L-number such that the derived BP-number substantially equals the L-number divided by a preset non-integer divide ratio; and
a means for modulating a second wave that is to be received by the reader by encoding symbols with a periodicity determined from the BP-number. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
-
-
53. A method for an RFID tag, comprising:
-
receiving a first wireless wave having a waveform;
determining an L-number from a duration of a calibration feature of the waveform;
deriving a BP-number by combining a first nonzero version of the L-number with a second nonzero version of the L-number such that the derived BP-number substantially equals the L-number divided by a preset non-integer divide ratio; and
modulating a second wave that encodes symbols with a periodicity determined from the BP-number. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78)
-
Specification