RFID-tag communication device
First Claim
1. An RFID-tag communication device including an antenna from which a transmission signal is transmitted toward an RFID tag and through which a reply signal transmitted from the RFID tag in response to the transmission signal is received, for radio communication with the RFID tag, said RFID-tag communication device comprising:
- a first-cancel-signal output portion operable to generate a digital first cancel signal for suppressing a leakage signal from a received signal which is received through said antenna and which contains said leakage signal as well as said reply signal, said leakage signal being a part of said transmission signal which is transmitted from said antenna and which is returned to and received by said antenna;
a first-cancel-signal control portion operable to control an amplitude and/or a phase of said first cancel signal generated by said first-cancel-signal output portion;
a first-cancel-signal D/A converting portion operable to convert said first cancel signal, after said first cancel signal is generated by said first-cancel-signal output portion and controlled by said first-cancel-signal control portion, into an analog signal;
a first signal combining portion operable to combine together the analog first cancel signal generated by said first-cancel-signal D/A converting portion, and said received signal, to obtain a first composite signal;
a second-cancel-signal output portion operable to generate a digital second cancel signal for suppressing said leakage signal from said received signal;
a second-cancel-signal control portion operable to control an amplitude and/or a phase of said second cancel signal generated by said second-cancel-signal output portion;
a second-cancel-signal D/A converting portion operable to convert said second cancel signal generated by said second-cancel-signal output portion, into an analog signal;
a second signal combining portion operable to combine together the analog second cancel signal generated by said second-cancel-signal D/A converting portion, and said first composite signal, to obtain a second composite signal;
a demodulating portion operable to demodulate said second composite signal generated by said second signal combining portion; and
a direct-current-component detecting portion operable to detect a direct current component of the second composite signal demodulated by said demodulating portion, andwherein said second-cancel-signal control portion controls a phase of said second cancel signal on the basis of the direct current component of the demodulated second composite signal detected by said direct-current-component detecting portion.
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Accused Products
Abstract
An RFID-tag communication device including (a) an antenna from which a transmission signal is transmitted toward an RFID tag and through which a reply signal transmitted from the RFID tag in response to the transmission signal is received, for radio communication with the RFID tag, (b) a first-cancel-signal output portion operable to generate a digital first cancel signal for suppressing a leakage signal from a received signal which is received through the antenna and which contains the leakage signal as well as the rely signal, the leakage signal being a part of the transmission signal which is transmitted from the antenna and which is returned to and received by the antenna, (c) a first-cancel-signal control portion operable to control an amplitude and/or a phase of the first cancel signal generated by the first-cancel-signal output portion, (d) a first-cancel-signal D/A converting portion operable to convert the first cancel signal generated by the first-cancel-signal output portion, into an analog signal, (e) a first signal combining portion operable to combine together the analog first cancel signal generated by the first-cancel-signal D/A converting portion, and the received signal, to obtain a first composite signal.teh
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Citations
32 Claims
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1. An RFID-tag communication device including an antenna from which a transmission signal is transmitted toward an RFID tag and through which a reply signal transmitted from the RFID tag in response to the transmission signal is received, for radio communication with the RFID tag, said RFID-tag communication device comprising:
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a first-cancel-signal output portion operable to generate a digital first cancel signal for suppressing a leakage signal from a received signal which is received through said antenna and which contains said leakage signal as well as said reply signal, said leakage signal being a part of said transmission signal which is transmitted from said antenna and which is returned to and received by said antenna; a first-cancel-signal control portion operable to control an amplitude and/or a phase of said first cancel signal generated by said first-cancel-signal output portion; a first-cancel-signal D/A converting portion operable to convert said first cancel signal, after said first cancel signal is generated by said first-cancel-signal output portion and controlled by said first-cancel-signal control portion, into an analog signal; a first signal combining portion operable to combine together the analog first cancel signal generated by said first-cancel-signal D/A converting portion, and said received signal, to obtain a first composite signal; a second-cancel-signal output portion operable to generate a digital second cancel signal for suppressing said leakage signal from said received signal; a second-cancel-signal control portion operable to control an amplitude and/or a phase of said second cancel signal generated by said second-cancel-signal output portion; a second-cancel-signal D/A converting portion operable to convert said second cancel signal generated by said second-cancel-signal output portion, into an analog signal; a second signal combining portion operable to combine together the analog second cancel signal generated by said second-cancel-signal D/A converting portion, and said first composite signal, to obtain a second composite signal; a demodulating portion operable to demodulate said second composite signal generated by said second signal combining portion; and a direct-current-component detecting portion operable to detect a direct current component of the second composite signal demodulated by said demodulating portion, and wherein said second-cancel-signal control portion controls a phase of said second cancel signal on the basis of the direct current component of the demodulated second composite signal detected by said direct-current-component detecting portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An RFID-tag communication device including an antenna from which a transmission signal is transmitted toward an RFID tag and through which a reply signal transmitted from the RFID tag in response to the transmission signal is received, for radio communication with the RFID tag, said RFID-tag communication device comprising:
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a first-cancel-signal output portion operable to generate a digital first cancel signal for suppressing a leakage signal from a received signal which is received through said antenna and which contains said leakage signal as well as said reply signal, said leakage signal being a part of said transmission signal which is transmitted from said antenna and which is returned to and received by said antenna; a first-cancel-signal control portion operable to control an amplitude and/or a phase of said first cancel signal generated by said first-cancel-signal output portion; a first-cancel-signal D/A converting portion operable to convert said first cancel signal, after said first cancel signal is generated by said first-cancel-signal output portion and controlled by said first-cancel-signal control portion, into an analog signal; a first signal combining portion operable to combine together the analog first cancel signal generated by said first-cancel-signal D/A converting portion, and said received signal, to obtain a first composite signal; a digital-transmission-signal output portion operable to generate said transmission signal in the form of a digital signal; and a table storing a sine-wave or cosine-wave table which represents predetermined sampling values corresponding to respective phases at predetermined sampling points, wherein said digital-transmission-signal output portion generates said transmission signal on the basis of said sine-wave or cosine-wave table; further comprising a second-cancel-signal output portion operable to generate said second cancel signal on the basis of said sine-wave or cosine-wave table, and a second-cancel-signal control portion operable to control a phase of said second cancel signal, by changing positions of said sine-wave or cosine-wave table from which said sampling values are read out. - View Dependent Claims (18)
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19. An RFID-tag communication device including an antenna from which a transmission signal is transmitted toward an RFID tag and through which a reply signal transmitted from the RFID tag in response to the transmission signal is received, for radio communication with the RFID tag, said RFID-tag communication device comprising:
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a first-cancel-signal output portion operable to generate a digital first cancel signal for suppressing a leakage signal from a received signal which is received through said antenna and which contains said leakage signal as well as said reply signal, said leakage signal being a part of said transmission signal which is transmitted from said antenna and which is returned to and received by said antenna; a first-cancel-signal control portion operable to control an amplitude and/or a phase of said first cancel signal generated by said first-cancel-signal output portion; a first-cancel-signal D/A converting portion operable to convert said first cancel signal, after said first cancel signal is generated by said first-cancel-signal output portion and controlled by said first-cancel-signal control portion, into an analog signal; a first signal combining portion operable to combine together the analog first cancel signal generated by said first-cancel-signal D/A converting portion, and said received signal, to obtain a first composite signal; a sine-wave-signal generating portion operable to generate a first sine-wave signal and a second sine-wave signal which have respective different phases; an amplitude control portion operable to control amplitudes of said first and second sine-wave signals generated by said sine-wave-signal generating portion; and a sine-wave synthesizing portion operable to combine together said first and second sine-wave signals the amplitudes of which have been controlled by said amplitude control portion, to synthesize a composite sine-wave signal for radio communication. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification