| 摘要 |
PROBLEM TO BE SOLVED: To reliably separate a signal from a noise in a squelch operation of a wireless reception signal. SOLUTION: After a wireless carrier wave signal is converted into a digital form, it is envelope-detected (20) and filtered (22). A noise estimation function 24 estimates a noise of a detection signal due to atmospheric conditions, and a noise by a gain in a noise index characteristics of a circuit, thereby generating a noise estimation signal. The noise estimation signal is used for calculating a squelch threshold signal (50), and it is determined whether or not a power of a signal derived from the detection signal exceeds a threshold (52). When exceeding the threshold, the detection signal is output to an output path 56 through a signal conditioner 54 consisting of a switch.
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