Distance measuring apparatus, distance measuring method, reflector, and communication system
First Claim
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1. A distance measuring apparatus, comprising:
- a transmitter, configured to transmit first one-frame signals from an antenna via radio waves having three or more different carrier frequencies, each of the first one-frame signals being composed of a request signal and a continuous carrier wave;
a receiver, configured to receive second one-frame signals generated when the first one-frame signals are reflected by a reflector while being modulated, each of the second one-frame signals having a frequency corresponding to a frequency of an associated one of the first one-frame signals;
a phase information acquirer, configured to calculate a phase change amount between the first one-frame signals and the second one-frame signals for each of the carrier frequencies; and
a distance calculator, configured to calculate a distance between the antenna and the reflector by high-resolution spectrum analysis, on the basis of the carrier frequencies and the phase change amount calculated for each of the carrier frequencies.
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Abstract
A transmission controller 7B is configured to transmit an R/W request signal for requesting transmission of a tag response signal to a RFID tag 1 twice. At this time, a frequency controller 7A controls a PLL section 5A to transmit the R/W request signal via different carrier frequencies. A phase information acquirer 8A detects a phase change amount of the tag response signal that is transmitted via different carrier frequencies. A distance calculator 8B calculates the distance between the reader/writer 2 and the RFID tag 1 on the basis of the phase change amount.
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Citations
14 Claims
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1. A distance measuring apparatus, comprising:
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a transmitter, configured to transmit first one-frame signals from an antenna via radio waves having three or more different carrier frequencies, each of the first one-frame signals being composed of a request signal and a continuous carrier wave; a receiver, configured to receive second one-frame signals generated when the first one-frame signals are reflected by a reflector while being modulated, each of the second one-frame signals having a frequency corresponding to a frequency of an associated one of the first one-frame signals; a phase information acquirer, configured to calculate a phase change amount between the first one-frame signals and the second one-frame signals for each of the carrier frequencies; and a distance calculator, configured to calculate a distance between the antenna and the reflector by high-resolution spectrum analysis, on the basis of the carrier frequencies and the phase change amount calculated for each of the carrier frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A distance measuring method, comprising:
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transmitting first one-frame signals from an antenna via radio waves having three or more different carrier frequencies, each of the first one-frame signals being composed of a request signal and a continuous carrier wave; receiving second one-frame signals generated when the first one-frame signals are reflected by a reflector while being modulated, each of the second one-frame signals having a frequency corresponding to a frequency of an associated one of the first one-frame signals; calculating a phase change amount between the first one-frame signals and the second one-frame signals for each of the carrier frequencies; and calculating a distance between the antenna and the reflector by high-resolution spectrum analysis, on the basis of the carrier frequencies and the phase change amount calculated for each of the carrier frequencies. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification