METHOD OF DETERMINING TRUE VELOCITY OF SHIP FROM MEASUREMENTS OF TRAVEL DISTANCE ON TACK FROM FIXED CONSTELLATION OF SPACECRAFT OF MID-ORBIT SATELLITE RADIO NAVIGATION SYSTEM Russian patent published in 2015 - IPC G01C21/00 

FIELD: physics, navigation.

SUBSTANCE: invention relates to marine navigation and can be used particularly to determine velocity of a ship. The disclosed method of determining the true velocity of a ship from measurements of the travel distance of the ship on tack from a fixed constellation of spacecraft of a mid-orbit satellite radio navigation system includes receiving spacecraft radio signals; picking up overhead information from the radio signals; determining, based on the overhead information, the composition of working constellations of spacecraft of the system for the time of the beginning and end of the travel; measuring radio navigation parameters of signals of spacecraft of working constellations at said time of the beginning and end of the travel; converting the measured parameters into coordinates of the ship at the beginning and end of travel and determining the travel distance as the distance between points with the obtained coordinates, wherein after determining, based on the overhead information, the composition of working constellations of spacecraft of the system for the beginning and end of the travel, the composition of said constellations is compared by selecting a group that is common for both constellations of spacecraft and designating the selected group as the signal working constellation for the entire duration of travel, wherein for the entire duration of travel while simultaneously receiving radio signals from spacecraft, the method includes further determining and estimating residual error of the Doppler radio log in the primary velocity mode; calculating posterior mean-square error of velocity from the log to compensate for roll and pitch; calculating the desired horizontal components of the velocity vector.

EFFECT: invention is aimed at broadening functional capabilities of the method of determining the travel distance of a ship on tack based on location while simultaneously reducing the effect of negative factors on determining the true velocity of the ship.