Patent ID: 6289280
Filing Date: 2001-09-11
Classification: G01S

Abstract:
A method for determining in a processing unit the location of a device including:a) receiving range information, pseudo-range information, and difference of arrival information related to a particular location sought to be determined, the range information being the distance between the location of the device and a first transmission point, the pseudo-range information being the distance between the location of the device and a second transmission point plus a clock bias, and the difference of arrival information being the difference between the time at which a reference signal transmitted from a third transmission point arrived at the location of the device and the time at which a second signal transmitted from a fourth transmission point arrived at the location of the device;b) using a plane-wave approximation to eliminate any unknown second order terms associated with the pseudo-range information;c) substituting a first quadratic variable for any unknown second order terms in the range information;d) constructing a coordinate frame with one of the transmission points associated with the range information, the pseudo-range information, or the difference of arrival information as the origin of the coordinate frame;e) expressing as a set of equations, the range difference of arrival, range, and pseudo-range information in terms of the newly constructed coordinate frame;f) substituting a second quadratic variable for the coordinates of the unknown location, thus placing the equation for the difference of arrival, range, and pseudo-range information in the same form;g) concatenating the equations for the range, pseudo-range and difference of arrival information into a single set of equations;h) expressing the coordinates of the location of the device and the time bias as a function of the quadratic variable;i) solving for the second quadratic variable, and thus determining two solutions for the location sought; andj) outputting the location sought.