초록

Microwave signals are injected at one end of a slotted waveguide containing a shorting stub which is moved along the length of the waveguide. The distance to the shorting stub is determined from the comparative phase characteristics of the injected signals reflected back from the shorting stub.

대표청구항 ▼

Apparatus for sensing the distance to an object, characterized by: a microwave signal source, a contained medium for propagating microwave signals along its length, said medium including a reflector member along the length of the medium for reflecting the signals back, and detection means responsive

Apparatus for sensing the distance to an object, characterized by: a microwave signal source, a contained medium for propagating microwave signals along its length, said medium including a reflector member along the length of the medium for reflecting the signals back, and detection means responsive to input signals for providing an output signal which reflects the phase difference between said input signal and a reference signal, said signal from said microwave source being applied to said medium, said input signal being a signal reflected back from the reflector member and said reference signal being said microwave signal, the object being connected to said reflector member, and said microwave source comprising means for providing a microwave signal comprising at least first and second modulated signals, the modulating frequency of one of said signals being such that its period, for one cycle, equals the round trip transmission time for the carrier for the maximum distance to be measured and the modulation frequency of the second frequency being higher than said first frequency, said detection means comprising means responsive to an input signal comprising said second signal for providing a demodulation signal reflecting the modulated portion, if any, of said input signal, means for providing a first distance indicating signal reflecting the phase difference between said demodulation signal and a first reference signal having the same frequency as said first modulation signal, means for providing a second distance indicating signal reflecting the phase difference between said demodulation signal and a reference signal having the same frequency as said second modulation signal, and for providing a signal reflecting the sum of the distances associated with said distance signals.