Geolocation of an electromagnetic emitter utilizing receptor pattern slope
AssigneeSoftronics, Ltd.
InventorRobert H. Sternowski
Life of this patent
Estimating the term…
Abstract
Directional antennas comprising substantially identical radiation patterns separated in a horizontal plane by an index angle. A line of bearing to an emitter is determined by a ratio of the power level of an EM signal received by the directional antennas and comparing it to a lookup table to determine an angle off of the boresight of the directional antenna with the highest received power level of the EM signal toward the directional antenna with the second-highest received power level of the EM signal that the emitter of the EM signal is located.
Claims18
A wideband direction finding system for determining a line of bearing to an emitter of an electromagnetic (EM) signal, the system comprising:
- at least three EM sensors comprising substantially identical radiation patterns separated in a horizontal plane by an index angle;
- at least one power measurement device connected to the at least three EM sensors for determining a power level of the EM signal at each of the at least three EM sensors;
- a processor connected to the at least one power measurement device to receive the power level of the EM signal at each of the at least three EM sensors and to calculate a ratio of the power level of the EM signal at adjacent EM sensors of the at least three EM sensors;
- a line of bearing engine containing a lookup table comprising for each frequency of a plurality of frequencies a ratio between 0 and K, inclusive, where K is a constant of the EM Sensor of the at least three EM sensors at each frequency of the plurality of frequencies, and a corresponding angle between 0 and ½ times the index angle, inclusive, and configured to determine the line of bearing to the emitter from the ratio of the power level.
A method for determining a line of bearing to an emitter of an electromagnetic (EM) signal based on a power level of the EM signal, the method comprising:
- determining the power level of the EM signal at at least three EM sensors each of which comprising substantially identical radiation patterns separated in a horizontal plane by an index angle;
- identifying which of the at least three EM sensors is oriented most directly toward the emitter based on the power level of the EM signal at the at least three EM sensors;
- providing a lookup table comprising for each frequency of a plurality of frequencies a ratio between 0 and K, inclusive, where K is a constant of the EM Sensor at each frequency of the plurality of frequencies, and a corresponding angle between 0 and ½ times the index angle, inclusive;
- and
- determining the frequency of the EM signal and the line of bearing to the emitter based on a ratio of the power level of the EM signal from two EM sensors of the at least three EM sensors relative to an index angle between the two EM sensors.
Dependencies are inferred from the claim text.