Patent ID: 8233872
Filing Date: 2012-07-31
Classification: G01S,G06K,H04B

Abstract:
1. A radio-frequency communication device comprising a splitting unit splitting a carrier wave component of a transmitted signal transmitted via a transmission antenna, an amplitude controlling unit controlling an amplitude of the carrier wave component split by the splitting unit, a phase controlling unit controlling a phase of the carrier wave component split by the splitting unit, and a cancel signal synthesizing unit adding a cancel signal generated with the carrier wave component via the amplitude controlling unit and the phase controlling unit to a received signal received via a reception antenna, the radio-frequency communication device characterized by: a cancel signal supply suppressing unit that selectively suppresses supply of the cancel signal to the cancel signal synthesizing unit; a received-signal terminating unit that selectively terminates a received-signal input terminal from the reception antenna to the cancel signal synthesizing unit; a signal strength detecting unit that detects strengths of the cancel signal, the received signal, and a synthesized signal of the cancel signal and the received signal; a memory unit that stores the strength of the received signal detected by the signal strength detecting unit; a signal strength comparing unit that compares the strength of the received signal read out from the memory unit with the strength of the cancel signal detected by the signal strength detecting unit; and a cancel signal controlling unit that controls an amplitude and a phase of the cancel signal via the amplitude controlling unit and the phase controlling unit based on a comparison result by the signal strength comparing unit; wherein the strength of the cancel signal is detected by the signal strength detecting unit by detecting the strength of the synthesized signal when the received-signal terminating unit terminates the received signal input terminal; the strength of the received signal is detected by the signal strength detecting unit by detecting the strength of the synthesized signal when the cancel signal supply suppressing unit suppresses the supply of the cancel signal; and first, in a state allowing the cancel signal supply suppressing unit to suppress cancel signal supply to the cancel signal synthesizing unit, the cancel signal controlling unit allows the signal strength detecting unit to detect the strength of the received signal and then allows the memory unit to store a result of the detection; next, in a state releasing the suppression of the cancel signal supply to the cancel signal synthesizing unit and allowing the received-signal terminating unit to terminate the received-signal input terminal, the cancel signal controlling unit controls the amplitude of the cancel signal such that the strength of the cancel signal detected by the signal strength detecting unit is made equal to the strength of the received signal stored in the memory unit; and next, in a state releasing the termination of the received-signal input terminal by the received-signal terminating unit, the cancel signal controlling unit separately controls a phase of the cancel signal from the amplitude of the cancel signal such that the strength of the synthesized signal of the received signal and the cancel signal detected by the signal strength detecting unit is maximally reduced.