| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus and a method for canceling noises of an AM-broadcasting transmitter-receiver to theoretically completely eliminate the noises generated by the AM broadcasting transmitter-receiver. SOLUTION: The method for canceling the noise digitizes an intermediate-frequency signal of received signals, detects a noise level by monitoring a digitized intermediate-frequency signal (IF) 2, and synchronizes the IF at the noise level of PLL 7. The method multiplies the synchronized IF by the the detected noise level, confirms the synchronization of both signals by comparing a difference between the multiplied signal and the IF with a comparator 10, outputs the summary of the the multiplied signal and the IF which are added by an adder/subtractor device 9 if both signals are synchronized, and outputs the difference between the multiplied signal and the IF if both signals are not synchronized. Afterwards, the method subtracts the output signal of the adder/subtractor device from the double IF signal or subtracts half of the output signal of the adder/subtractor device from the IF. COPYRIGHT: (C)2004,JPO
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