| 摘要 |
A modulated alternating waveform produced by an oscillator is transmitted to a target and a receiver receives reflections of the waveform from the target. The waveform of the modulation also is applied through a voltage controlled phase shifter and squaring amplifier to a synchronous detector coupled to the receiver. In the synchronous detector, the signal and any spurious noise from the receiver is multiplied by the waveform from the squaring amplifier in a manner that cancels out all spurious noise. A DC voltage representative of the phase shift produced in the modulation of the received signal by the distance from transmitter to target to receiver is applied to an integrator. Integrator output is applied to the voltage controlled phase shifter and is representative of the distance traveled by the waveform.
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