| 摘要 |
PROBLEM TO BE SOLVED: To detect an intruder without being affected by an erroneous detection factor. SOLUTION: This detector is provided with a transmission means for transmitting an amplitude-modulated radio wave (wavelengthλ) to an intruder with a fixed period, the first reception means for receiving a reflected wave of the radio wave, the first mixer for combining the transmitted wave with the received wave in the first reception means, the first envelope detecting means for extracting a variable period component from an output of the first mixer means, the first level detecting means for detecting moving withinλ/4 of the intruder, the second reception means arranged to be shifted byλ/2 along a receiving direction with respect to the first reception means, the second mixer means for combining the transmitted wave with the reflected wave in the second reception means, the second envelope detecting means for extracting the variable period component from the output of the second mixer means, the second level detecting means for detecting moving withinλ/4 of the intruder, and a comparison means for outputtingλ/4 or more of moving quantity of the intruder in potential inversion timing of respective outputs from the first level detecting means and the second level detecting means.
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