Ultra short base line installation angle offset unbiased estimation method based on symmetric measuring line

The invention relates to an ultra short base line installation angle offset unbiased estimation method. Aiming at the problem that the ultra short base line installation angle offset estimation calculation precision is reduced because ultra short base line installation angle estimation value offset is caused by offset between arrival direction and target direction due to sound ray spread curve when an operation sound velocity section cannot be obtained, the invention provides the ultra short base line installation angle offset unbiased estimation method based on a symmetric measuring line. The method is realized by the following steps: step one, collecting ultra short base line (USBL) positioning data; step two, obtaining estimation residual vector; step three, finding out the minimum value in the standard deviation statistic value; and step four, obtaining the installation angle offset estimation value. The method is applied to the filed of ultra short base line installation angle offset unbiased estimation. According to the method, since the influence of a sound ray curve on horizontal and vertical installation deflection angle estimation is reduced, the ultra short base line installation angle estimation value offset is further reduced.