Original|Operation takes you to learn history
Although Langévin's work had a great impact on the future sonar design, his invention came too late to help the war. The first sonar device is a passive listening device, meaning that no signal is being sent. By 1918, both the United Kingdom and the United States had established active systems (active sonar signals were sent out and then recovered). An acoustic communication system is a sonar device in which both sides of the signal path have acoustic projectors and receivers. The invention of acoustic transducers and highly efficient acoustic projectors has made possible more advanced sonar forms possible.
Sonar - SO UND, NA vigation and - [R anging
There are two main types of sonar
The active sonar produces a sound pulse, commonly referred to as "ping", which then listens for the reflection of the pulse. The pulse can be a constant frequency or a frequency change. If it is a click, the receiver correlates the reflected frequency with a known "DI-U-". The resulting processing gain allows the receiver to derive the same information as if it were a shorter pulse with the same total power. Typically, long-distance active sonars use lower frequencies. The bass has the bass "BAH-WONG".
In order to measure the distance to the object, the time from the transmission of the pulse to the reception can be measured. Passive sonar can be listened to without transmission. They are usually military, although some are scientific. Passive sonar systems typically have large sonic databases. Computer systems often use these databases to identify vessel categories, actions (ie speed of the ship, or type of weapon released) and even specific vessels.