Method and apparatus for locating a terrestrial transmitter from a satellite
AssigneeAlcatel
InventorsFrancis Martinerie, Jean-Marc Bassaler
Life of this patent
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Abstract
The invention provides a method of determining the location of one or more terrestrial transmitters by measuring the electromagnetic field vector at a plurality of instants from an antenna of a satellite. The propagation direction of the electromagnetic field and the location of the transmitter are determined on the basis of the measured vectors. The invention also provides methods of locating a terrestrial transmitter by using a plurality of optionally geostationary satellites. The invention also provides a satellite comprising an antenna and means for implementing such methods.
Claims10
A method of locating a terrestrial transmitter by means of a geostationary satellite provided with an antenna, the method comprising the steps of:
- measuring, at the satellite, and at at least two different instants, three orthogonal components of an electromagnetic field transmitted by the terrestrial transmitter;
- calculating at least two electromagnetic field vectors from the measurements;
- determining the propagation direction of the electromagnetic field from the determined vectors;
- and
- locating the transmitter at the point of intersection between the surface of the earth and a straight line colinear with the propagation direction and passing through the satellite.
A method of using a moving satellite to locate a terrestrial transmitter transmitting a linearly polarized electromagnetic field, the method comprising the steps consisting in:
- measuring, at the satellite, and at at least two different instants, three orthogonal components of an electromagnetic field transmitted by the terrestrial transmitter;
- calculating electromagnetic field vectors from the measurements;
- for each measurement, determining a plane containing the propagation direction of the measured electromagnetic field and the satellite, on the basis of the calculated vectors;
- and
- locating the transmitter at the intersection of a plurality of circles where the planes intersect the surface of the earth.
A method of using a plurality of satellites to locate a terrestrial transmitter transmitting a linearly polarized electromagnetic field, the method comprising the steps consisting in:
- measuring, at the satellites, and at a common instant, three orthogonal components of an electromagnetic field transmitted by the terrestrial transmitter;
- calculating electromagnetic field vectors from the measurements;
- for each measurement, determining a plane containing the propagation direction of the measured electromagnetic field and the satellite, on the basis of the calculated vectors;
- and
- locating the transmitter at the intersection of a plurality of circles formed by the intersections of the planes and the surface of the earth.
A transmitter locating satellite having:
- an antenna;
- means for measuring, at the satellite, and at at least two different instants, three orthogonal components of an electromagnetic field transmitted by the terrestrial transmitter;
- means for calculating at least two electromagnetic field vectors from the measurements,
- means for determining the propagation direction of the electromagnetic field from the determined vectors;
- and
- means for locating the transmitter at the point of intersection between the surface of the earth and a straight line colinear with the propagation direction and passing through the satellite.
Dependencies are inferred from the claim text.