The technique has two approaches, namely single-beam echo sounder (SBES) and multi-beam echo sounder
(MBES). Transducers are placed over the side of the vessel, which transmit the sound waves to the sea bottom and
receive the reflected waves. The amount of time taken for the sound waves to reach sea bottom and reach back to
the receiver is used to determine the depth. Typically, SBES transmits and receives sound waves of single point,
wherein the MBES transmits sound waves in all directions and receives sound waves from multiple points, and
thus it has an advantage to map the depth over the widest range. Echo-sounding method is capable of determining
the depth accurately over the clear water, coastal environment where as in turbid water, the method lacks
performance due to infiltration of sound waves to the bottom of the ocean.
Recently, various airborne laser bathymetric (ALB) light detection and ranging (LiDAR) systems, such as
Scanning Hydrographic Operational Airborne Lidar Survey (SHOLAS), Compact Hydrographic Airborne Rapid
Total Survey (CHARTS), Laser Airborne Depth Sounder (LADS), and Experimental Advanced Airborne Research
Lidar (EAARL) are adopted to determine the bathymetry of the ocean. This method can effectively determine the
depth of both shallow and clear water, but this technique is only limited by its high purchasing and maintenance
costs. Almost all the above techniques are expensive