| 摘要 |
A radiation detector such as a radar detector is disclosed. The radiation detector includes a phase lock circuit with a modulating frequency oscillator, a radiation frequency antenna for receiving radiation, a radiation frequency modulator for modulating the radiation received with the modulating frequency, an envelope detector for detecting the modulated radiation envelope, an amplifier phase shift circuit AC coupled to the envelope detector and an alarm circuit. The phase lock circuit is responsive to the output of the amplifier-phase shift circuit. In one arrangement, the output of the phase lock circuit is a two state switch output responsive to the AC output of the amplifier-phase shift circuit. The radiation detector also includes a strip-type transmission line connecting the radiation frequency antenna, the radiation frequency modulator and the envelope detector. In one such arrangement, the radiation frequency modulator includes a p-i-n diode driven by the modulating frequency oscillator. A preferred arrangement of the envelope detector includes a Schottky diode in parallel with a capacitor connected between the conductors of the strip-type transmission line for half wave rectifying the modulated radiation. A signal attenuator attenuates the AC output of the amplifier-phase shift circuit when the phase lock circuit is in the second state so that the audible alarm phases in and out for weak signals.
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