What is an LBL?
Long Baseline (LBL), is a method of underwater acoustic positioning which is used to calculate the postioning of underwater targets, such as ROVs or subsea assests, with very high accuracy. LBL systems are well suited to deep water and challenging environments where precise positioning is critical.
How does an LBL work?
An LBL system consists of an array of transponders placed on the seafloor and a transciever, which is mounted on a ROV or vessel to be postioned. The seabed transponders are spaced apart, sometimes by hundereds of meters, to form a stable acoustic network across the area of operation.
An LBL system works by the transciever transmitting an acoustic interrogration signal which is detected by the seabed transponders. Each transponder then replies with its own unique acoustic signal, which is detected by the tranciever as well as a time stamp.
The time from the transmission of the interrogation signal until each reply is detected is measured by the LBL system and then converted into a range. This gives the distance from the transceiver to each transponder in the array.
The position of the target is then calculated using a method called trilateration. This requires ranges to at least three transponders at known positions, although four or more are preferred to provide redundancy and improve accuracy. With the correct setup, LBL systems can deliver centimetric accuracy, making them ideal for precision operations such as subsea construction and asset installation.
We have engineered a complete LBL solution which intergrates seamlessly into subsea operations. Our Compatt 6+ transponders form the seabed network, while the ROVNav 6+ or Dunker 6+ act as moblie transcievers which depends on whether it’s being deployed from an ROV or a surafce vessel.
The system is controlled through our Fusion 2 software, which provides intuitive control and real-time positioning.