What Is SONAR?
The word “SONAR” is an abbreviation for “SOund, Navigation, And Ranging.” An active SONAR system consists of a sound transmitter, a sound receiver, a signal processor and a display unit. When the transmitter and receiver are combined it is referred to as a transducer. A passive SONAR just listens, processes and displays detected sound.
Active SONAR creates a pulse of sound, often called a “ping,” and then listens for reflections (echo) of the pulse. This pulse of sound can be created electronically using a sonar projector, consisting of a signal generator, power amplifier and electro-acoustic transducer. Other methods of creating pulses of sound are mechanically or air driven and explosives can also be used.
In the simplest terms, an electrical impulse is converted into an acoustic sound pulse and transmitted into the water. When this wave strikes an object, it rebounds or echos. This echo strikes the receiver and is converted back into an electric signal. This signal is then amplified by the receiver, processed and sent to a display unit.
To measure the distance to an object, the time from transmission of a pulse to the reception of that pulse’s echo is measured and converted into a range by knowing the speed of sound in water (approximately 4800 feet per second).
When active SONAR is used to measure the distance from the transducer to the bottom, it is known as echo sounding.
