US 6,040,898 A · FMCW distance measurement process

Abstract

In an FMCW distance measurement process, a wave train of carrier frequency f.sub.0 is modulated with a time function f(t) and subdivided into a transmission signal and into a reference signal in deterministic phase relationship with the transmission signal; the transmission signal is sent on a transmission section to be measured and the reference signal is supplied to a phase difference-forming arrangement; the signal reflected in the transmission section with a delay that corresponds to propagation time .tau. is also supplied as a reception signal to the phase difference-forming arrangement that forms the time difference function .theta.(t) between the phases of reference and reception signals; the phase difference function .theta.(t) is separately evaluated in a continuous fraction .theta..sub.= that corresponds to the carrier frequency f.sub.0 and in an alternating fraction .theta..sub.- (t) that corresponds to the modulation time function f(t); and the propagation time .tau. proportional to the distance is finally determined by evaluating together both phase difference information.

Claims11

Dependent claims

A FMCW distance measurement method, comprising:

modulating a wave train of carrier frequency f.sub.0 by a time function f(t) and splitting said wave train into a transmission signal and a reference signal in a deterministic phase relationship;
putting the transmission signal onto a transmission link to be measured and feeding the reference signal to a phase difference-forming arrangement;
feeding a signal reflected in the transmission link and delayed by the propagation time .tau. as a reception signal to the phase difference-forming arrangement;
wherein the phase difference-forming arrangement forms the time difference function .theta.(t) of the phases between the reference and reception signals;
evaluating the phase difference function .theta.(t) separately with respect to a direct component .theta..sub.= =g'(.tau., f.sub.0) assigned to the carrier frequency f.sub.0 and with respect to an alternating component .theta..sub.- (t)=g"(.tau., f.sub.- (t)) assigned to the modulation time function f(t);
and
determining the propagation time .tau. proportional to the distance by a combined evaluation of said direct component and said alternating component of the phase difference function.

4 more elements

A FMCW distance measurement apparatus, comprising:

a transmitter coupled to a modulator, said transmitter generating a modulated wave-form;
a receiver to receive a portion of said modulated waveform that is reflected off a target;
a quadrature receiver to receive a reception signal corresponding to an electrical representation of said reflected portion of said modulated waveform and a reference signal corresponding to said transmitted modulated waveform, wherein said quadrature receiver generates a complex phasor having a time phase function corresponding to a phase difference function .theta.(t) between said reference signal and said reception signal;
and
a processor coupled to said quadrature receiver to evaluate said phase difference function .theta.(t) separately with respect to a direct component .theta..sub.= =g'(.tau., f.sub.0) assigned to a carrier frequency f.sub.0 and with respect to an alternating component .theta..sub.- (t)=g"(.tau., f.sub.- (t)) assigned to a modulation time function f(t) and to determine a propagation time .tau. proportional to the distance to said target by a combined evaluation said direct component and said alternating component of the phase difference function.

2 more elements

Dependencies are inferred from the claim text.

FMCW distance measurement process

Life of this patent

FMCW distance measurement process

Life of this patent

Abstract

Claims11