Sonar

1 Sonar

Sonar (Sound Navigation and Ranging) is used in boats and ships to measure distance between the boat and the seafloor or another object. Sonar device transmits and receives sound waves. When the sound velocity in a substance is known, the distance between measurable object and test device can be calculated. Speed of sound multiplied by time delay between transmitted and received sound waves gives distance. With multiple sonar sensors object location can be calculated.

Image 1.1 Basic functionality Sonar system

Image 1.2 Acoustic torpedo

2. Ultrasound measurement device

Ultrasound or ultrasonic is sound waves frequencies higher than upper limit human hearing range. Ultrasound measurement device includes transmitter and receiver. These two components are often combined into one block called transducer. Transducer is used for electric signal and ultrasound conversions.  Analog circuits are used for signal processing, transmitters power amplifier, receivers comparator and possible oscillators and filters. Control, counter and data handling circuits are most likely logical digital circuits. Microcontroller is used for data analysis and calculations.

Image 2.1  block diagram example

3. Applications

Most commonly ultrasonic technology is used in underwater applications. This technology is often used in the military applications eg. underwater communications, submarine navigation and mine countermeasures. In civilian purposes sonar is mostly used for location applications, echo sounding and fisheries. Sonar is also used in multiple scientific applications. Also nowadays, with the development of wireless technology, ultrasonic distance measurement can be used in small wireless devices to transmit all kinds of data.

Image 3.1 Sonar image of a shipwreckage

Sources:

http://www.ti.com/lit/an/slaa136a/slaa136a.pdf

http://www.analog.com/media/en/reference-design-documentation/reference-designs/CN0343.pdf

Images:

https://upload.wikimedia.org/wikipedia/commons/thumb/0/07/Sonar_Principle_EN.svg/800px-Sonar_Principle_EN.svg.png

 http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/AcousticHomingDiagram.svg/300px-AcousticHomingDiagram.svg.png

http://image.slidesharecdn.com/ultrasonictransducer-120914042111-phpapp01/95/ultrasonic-transducer-6-728.jpg?cb=1347596512