Objectives  This research aims to obtain accurate positioning in underwater towing and facilitate its use and deployment during experiments.

  Methods  Long baseline and ultra-short baseline acoustic technology are combined, the rough position of a towed target is obtained using the ultra-short baseline positioning array and the position is used as a priori data for long baseline positioning. On this basis, the long baseline array elements of the deck unit transducer and ultra-short baseline positioning array are combined with the short-term baseline positioning a priori data and long baseline positioning technology so as to obtain higher positioning accuracy.

  Results  The long-baseline and ultra-short baseline joint positioning method is used to improve the positioning accuracy of towed underwater targets. The results of positioning accuracy tests conducted on a lake show that the Root-Mean-Square(RMS) error is 6.8 m when the ultra-short baseline method is adopted. However, the RMS value is just 2.5 m when the long baseline and ultra-short baseline are combined, solving the problem of positioning accuracy within short distances.

  Conclusions  By combining the long-range baseline information of the deck unit's ranging information and the ultra-short baseline positioning results, this technology can achieve the high-precision positioning of towed underwater targets and provide technical support for the specific needs of offshore testing and operations.