page_title: Short baseline acoustic positioning system
hierarchical_section_title: Short baseline acoustic positioning system
caption_attribution_description: Operation of a Short Baseline (SBL) Acoustic Positioning System: Surface station sonar transducer (A) sends an interrogate that is received by a transponder mounted on the tracked target (B). The transponder reply is received by three or more surface transducers (A, C, D). The positioning system determines distances B-A, B-C and B-D by measuring the signal run time and multiplying by the speed of sound. These distances in conjunction with depth information such as from a depth sensor on the tracked target are used to triangulate the target positions. Tracking precision depends on the spacing of the baseline (surface) transducers and the distance of the target. Wider spacing yields better precision.
context_page_description: A short baseline acoustic positioning system is one of three broad classes of underwater acoustic positioning systems that are used to track underwater vehicles and divers. The other two classes are ultra short baseline systems and long baseline systems. Like USBL systems, SBL systems do not require any seafloor mounted transponders or equipment and are thus suitable for tracking underwater targets from boats or ships that are either anchored or under way. However, unlike USBL systems, which offer a fixed accuracy, SBL positioning accuracy improves with transducer spacing. Thus, where space permits, such as when operating from larger vessels or a dock, the SBL system can achieve a precision and position robustness that is similar to that of sea floor mounted LBL systems, making the system suitable for high-accuracy survey work. When operating from a smaller vessel where transducer spacing is limited, the SBL system will exhibit reduced precision.
context_section_description: A short baseline (SBL) acoustic positioning system is one of three broad classes of underwater acoustic positioning systems that are used to track underwater vehicles and divers. The other two classes are ultra short baseline systems (USBL) and long baseline systems (LBL). Like USBL systems, SBL systems do not require any seafloor mounted transponders or equipment and are thus suitable for tracking underwater targets from boats or ships that are either anchored or under way. However, unlike USBL systems, which offer a fixed accuracy, SBL positioning accuracy improves with transducer spacing. Thus, where space permits, such as when operating from larger vessels or a dock, the SBL system can achieve a precision and position robustness that is similar to that of sea floor mounted LBL systems, making the system suitable for high-accuracy survey work.  When operating from a smaller vessel where transducer spacing is limited (i.e. when the baseline is short), the SBL system will exhibit reduced precision.
caption: Figure 1: Method of operation of a short baseline (SBL) acoustic positioning system for ROV
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