Flexible signal source location apparatus and method therefor

A method of providing an initial estimate of a location of a subscriber unit that is emitting a signal comprising the steps of:

• receiving at least two measurements of said signal, each of said measurements having a measurement error associated therewith;
• generating a surface contour for each measurement;
• finding intersection points and near intersection points between said surface contours and a surface contour representing earth's surface;
• using said intersection points and near intersection points to seed a least-squares algorithm to generate final locations;
• generating statistical confidence regions around each final location using said measurement error, each confidence region having a probability associated therewith indicating the probability that said subscriber unit is within the associated confidence region, each confidence region corresponding with a geographic region on earth's surface;
• and
• when smaller confidence regions are desired, collecting additional measurements of said signal and repeating the steps of sending, finding, using and generating to increase said probability associated with each confidence region.

An apparatus for determining a location of a signal source comprising:

• an earth terminal receiver for receiving measurements collected by a satellite, said measurements being from said signal source on or near earth's surface, said satellite being part of a satellite based communication system;
• and
• a processor for:
• generating a surface contour for each of said measurements;
• finding intersection points and near intersection points between said surface contours and a surface contour representing earth's surface;
• using said intersection points and near intersection points to seed a least-squares algorithm to generate final locations;
• generating statistical confidence regions around each final location using a measurement error associated with each of said measurement, each confidence region having a probability associated therewith indicating the probability that said signal source is within the associated confidence region, each confidence region corresponding with a geographic region on earth's surface;
• and
• when smaller confidence regions are desired, collecting additional measurements of said signal source and repeating the steps of sending, finding, using and generating to increase said probability associated with each confidence region.