Patent ID: 7987047
Filing Date: 2011-07-26
Classification: G01C,G01S

Abstract:
1. Navigation equipment comprising: a radio wave receiving unit for receiving radio waves emitted from a plurality of GPS satellites; a signal processing unit for identifying the GPS satellites which are emission sources of the radio waves received by said radio wave receiving unit to measure a pseudo range and a range rate of each of these identified GPS satellites, and for extracting a navigation message included in each of said radio waves; a GPS satellite behavior estimating unit for calculating a position and a velocity of each of the GPS satellites from the navigation message extracted by said signal processing unit; a pseudo range error estimating unit for estimating a pseudo range error on a basis of the pseudo range and the range rate which are measured by said signal processing unit; a user position observing unit for calculating a position of the navigation equipment by using the pseudo range measured by said signal processing unit, the position of each of the GPS satellites calculated by said GPS satellite behavior estimating unit, and the pseudo range error estimated by said pseudo range error estimating unit; a user velocity and heading observing unit for calculating a velocity of the navigation equipment from the range rate measured by said signal processing unit, the position of each of the GPS satellites calculated by said GPS satellite behavior estimating unit, and the position of the navigation equipment calculated by said user position observing unit; and a user heading searching unit for, when a multipath error included in the pseudo range error estimated by said pseudo range error estimating unit is smaller than a specified value, searching for, as a heading of the navigation equipment, a heading whose range rate, which is calculated on a basis of a relative movement of the navigation equipment having the position acquired by said user position observing unit and the velocity acquired by said user velocity and heading observing unit at a time when the navigation equipment changes its heading within a predetermined angle range with respect to a GPS satellite having the position and the velocity estimated by said GPS satellite behavior estimating unit, matches the range rate measured by said signal processing unit.