How is ultrashort baseline acoustic position determined?

Ultrashort baseline (USBL) acoustic positioning systems use multiple transducer elements to determine the position of an underwater object, such as a Remotely Operated Vehicle (ROV) or a dive support vessel. The key to understanding how USBL systems work lies in the concept of phase shift, which is the core principle behind the determination of position in this method.

In a USBL system, signals are emitted from a transducer and received at multiple elements of the same transducer array. By analyzing the phase shift of the received signals at these different elements, the system can accurately calculate the angle from the transducer to the target. This phase difference provides critical information about the target's position relative to the transducer.

This method is advantageous because it allows for rapid and continuous positioning updates, essential for dynamic positioning applications where precise control is required.

Other methods, such as measuring signal strength or round trip travel time, do not provide the same level of accuracy or responsiveness in determining position, and relying solely on time differences between readings can introduce inaccuracies due to the variable nature of acoustic transmissions in water. Therefore, the phase shift between elements in a single transducer is the most accurate and suitable method for determining position in ultrashort baseline