摘要 |
A process for measuring the distance of a moving body (12) from a fixed part (10), characterized in that it comprises the steps of: - generating a first alternating signal (r(t)) having a frequency within the radio-wave range or of elastic-wave range; - emitting the first signal from the fixed part towards the moving body (12); - receiving the first signal (r(t) on the moving body (12) and generating, on the moving body (12), a second signal (s(t)) having a frequency (nf) equal to the frequency (f) of the first signal (r(t)) multiplied by a constant factor (n), the second signal (s(t)) having an initial phase (.phi.l) equal to the phase (2.pi.ft1 + .phi.o) at the instant (t1) in which it is received by the moving body (12); - generating, on the fixed part, a third signal (u(t)) having a frequency (nf) equal to the frequency of the second signal (s~t~ ) and an initial phase (.phi.o) equal to the initial phase of the first signal (r(t)); and - determining the variation in distance of the moving body (12) in a pre-set time interval as a function of the variation in the amplitude of an alternating signal obtained from the sum of the second signal (s(t)) and the third signal (u(t)) in the same time interval.
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