Attitude Determination in a Survey Launch Using Multi-Antenna GPS Technologies

Multi-antenna GPS receiver configurations and methods are assessed to determine roll, pitch and azimuth of a survey launch operating at cruising speeds of 10 to 15 knots. Two receiver configurations are inter-compared, namely a 4antenna Ashtech 3DF system and a 3-GPSCardTM configuration. The survey launch antenna configurations and marine trials conducted to test these systems are described. The approach used to resolve the relative carrier phase ambiguities between the antennas is discussed and the use of antenna baseline constraints is analyzed. A least squares procedure which utilizes all the position information from the antennas for the estimation of the platform attitude parameters and their accuracy is presented. The attitude determination results of the two systems tested are inter-compared and show that the rms agreement between the two receiver configurations is better than 7 arc minutes for the pitch and yaw components and approximately 15 arc minutes for the roll component.