sonar
				   		Detection system emitting ultrasound; it is used for detection mainly in a marine environment.
				
 
					
					
					
						echo 
						Waves reflected by the target and measured by a remote sensing device.
				  	
 
					
						ship 
				  	 
					
						ultrasound waves emission 
						Production of very high-frequency sound vibrations whose echo is captured and analyzed.
				  	
 
					
						target 
						Surface or object from which sonar waves reflect.