Patent attributes
An interrogator that is to be incorporated in a communication system in which each of at least one transponder is operable, upon reception of a main carrier wave transmitted from the interrogator, to respond to the interrogator with a reflected wave that is generated by modulating the main carrier wave. The interrogator includes: (a) a transmitting portion operable to transmit the main carrier wave; (b) a receiving portion operable to receive the reflected wave as a received signal; (c) at least one first frequency-converter each operable to generate an intermediate frequency signal, by multiplying the received signal with a first local signal that is generated by a first local oscillator; (d) at least one second frequency-converter each operable to generate a demodulated signal, by multiplying the intermediate frequency signal or a converted signal converted from the intermediate frequency signal, with a second local signal that is generated by a second local oscillator; and (d) a phase controller operable to control phase of the second local signal.
