Abstract: Ultra short baseline positioning system can provide accurate positioning information for underwater equipment. The positioning results of the ultra short baseline positioning system contain a variety of factors, the effective processing of the data is the essential prerequisite for position precision. In this study, the acoustic antenna was calibrated, the accuracy of the positioning data was evaluated, the maritime collecting data were analyzed and the gross points of the raw data were filtered and removed. Finally, the reliable results of underwater positioning thereby can be acquired.

Key words: ultra short baseline, underwater positioning, accuracy evaluation, gross points