US 4,728,955 AGranted

Method for position-finding and apparatus herefor

AssigneeStiftelsen Institutet for Mikrovagsteknik vid Tekniska Hogskolan i Stockholm

InventorBengt Hane

Life of this patent

Estimating the term…

Loading patent…

Abstract

A method for determining a mutual position between two objects, comprising transmitting a microwave signal from the first object towards the second object, causing the second object to receive the transmittal signal and re-transmit a signal, which is caused to be received by the first object. According to the invention the first object includes a transmitter/receiver unit (S/M-unit), which transmits the aforesaid signal (f.sub.o) from a transmitter antenna. The second object (T) is caused to re-transmit the aforesaid signal modulated with a signal (f.sub.m), the first object being caused to receive the transmitted signal through at least two antennae (M.sub.1, M.sub.2) placed symmetrically on a respective side of the transmitter antenna (S) and in an antenna plane common with the transmitter antenna (S). The angle (.theta.) between the antenna plane and the second object, at least in one dimension, is determined by a phase comparison or an amplitude comparison of received signals, in dependance on whether or not the second object (T) is located in the so-called proximity zone of the first object. The invention also relates to apparatus for carrying out the method.

Claims10

Dependent claims

A method for determining a relative position between two objects, comprising transmitting a microwave signal from the first object, which comprises a transmitter receiver (S/M-unit), toward the second object, causing said second object to receive said signal and retransmit a signal which is caused to be received by the first object on at least two antennae (M.sub.1, M.sub.2), characterized in that the transmitter/receiver unit (S/M-unit) of the first object is caused to transmit said signal at a fixed frequency f.sub.o from a transmitter antenna;

in that the second object (T) is caused to re-transmit said signal modulated with a signal of frequency f.sub.m ;
in that the two antennae (M.sub.1, M.sub.2) of the first object are placed symmetrically on respective sides of the transmitter antenna (S) and in an antenna plane common with the transmitter antenna (S);
so that each of the two receiving antenna receives the retransmitted signal and in that an angle (.THETA.) between said antenna plane and said second object, at least in one dimension, namely in a first plane extending through the transmitter antenna and the two receiver antennae, is determined by a phase comparison or an amplitude comparison respectively of said received signals in dependence on whether the second object (T) is located in the so-called proximity zone of the first object or not, i.e. at a distance which is shorter than a distance of the same order of magnitude as the distance d between the two receiving antennae (M.sub.1, M.sub.2) or not, wherein when the second object (T) is located outside the proximity zone said angle (.THETA.) is determined by a phase comparison between the signal received on respective receiver antennae (M.sub.1, M.sub.2) subsequent to being mixed with the transmitted signal f.sub.o, where the phase difference (F.sub.2 -F.sub.1) between the received signals is determined;
and in that said angle (.THETA.) is determined from the equation expression ##EQU14## where F.sub.1 is a signal corresponding to the phase difference between the transmitted signal f.sub.o and one of the signals received by the S/M unit, F.sub.2 is a signal corresponding to the phase difference between the transmitted signal f.sub.o and the other of the signals received by the S/M unit, c is the speed of light and d is the distance between the two receiver antennae, by means of a computer unit (31) associated with the S/M-unit.

1 more element

Apparatus for determining a relative position between two objects, comprising a first object provided with a transmitter/receiver unit (S/M) adapted to transmit a microwave signal to the second object (T), said second object being adapted to receive a signal and re-transmit a signal which is arranged to be received by the transmitter/receiver unit (S/M) where the transmitter/receiver unit is provided with at least two receiver antennae (M.sub.1, M.sub.2) enabling receiving, on both antenna (M.sub.1, M.sub.2), the re-transmitted signal, and where the S/M-unit incorporates mixers (9,11;

17,18) arranged to mix the signal received from respective receiver antennae (M.sub.1, M.sub.2) with the transmitted signal, and include phasecomparison circuits (32,33) arranged to compare the phase position of respective received signals in relation to the phase of the transmitted signal;
characterized in that the transmitter/receiver unit (S/M) is adapted to transmit a signal of fixed frequency f.sub.o from a transmitter antenna (S);
in that the second object (T) is adapted to retransmit said signal modulated with a signal of frequency f.sub.m ;
in that said receiver antennae (M.sub.1, M.sub.2) are being placed symmetrically on a respective side of the transmitter antenna (S) and in an antenna plane common with the transmitter antenna (S) and in that a computer unit (31) is provided for calculating the phase difference (F.sub.2 -F.sub.1) between the received signals and adapted to calculate the angle .THETA. between said antenna plane and said second object (T), at least in one dimension, namely a first plane extending through the transmitter antenna (S) and the two receiver antennae (M.sub.1, M.sub.2) from the equation expression ##EQU20## where F.sub.1 is a signal corresponding to the phase difference between the transmitted signal f.sub.o and one of the signals received by the S/M unit and F.sub.2 is a signal corresponding to the phase difference between the transmitted signal f.sub.o and the other of the signals received by the S/M unit, c is the speed of light and d is the distance between the two receiver antennae M.sub.1, M.sub.2.

1 more element

Dependencies are inferred from the claim text.