Distance measurement using microwaves
First Claim
1. A method for determining the distance from an object including, generating a micro-wave frequency carrier wave, simultaneously modulating the carrier wave at two different frequencies to provide a modulated signal, directing a first portion of the modulated signal towards the object and receiving a reflected signal from the object directing a second portion of the modulated signal to form a reference signal non-linearly, cyclically varying the phase of one portion of the modulated signal, mixing the reflected signal with the reference signal, and detecting the difference frequency between the reflected signal and the reference signal, said difference frequency being proportional to the distance to be determined.
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Abstract
A distance measuring system, particularly suitable for targets which are moving slowly relative to a fixed reference point, such as the upper surface of the burden in a blast furnace. A doubly modulated microwave beam is directed at the target, and the reflected beam is mixed with part of the original beam, which part has its phase varied sinusoidally at a frequency lower than the modulating frequencies. The difference frequency detected between the phase-varied signal and the reflected signal is directly proportional to the distance to the target.
33 Citations
10 Claims
- 1. A method for determining the distance from an object including, generating a micro-wave frequency carrier wave, simultaneously modulating the carrier wave at two different frequencies to provide a modulated signal, directing a first portion of the modulated signal towards the object and receiving a reflected signal from the object directing a second portion of the modulated signal to form a reference signal non-linearly, cyclically varying the phase of one portion of the modulated signal, mixing the reflected signal with the reference signal, and detecting the difference frequency between the reflected signal and the reference signal, said difference frequency being proportional to the distance to be determined.
Specification