Ships use under-water sensors for detection and navigation. These sensors send and receive sound with ultrasonic frequency for detection. SONAR is the short form for Sound Navigation and Ranging. Let us build this prototype to understand the working of SONAR.

We will use an ultrasonic sensor, Aurdino with bluetooth module for the same.

I could not get a sensor which works under water. We will work with air as our medium for this prototype.

Data captured by the sensor is sent to the ‘Bluetooth terminal’ app on the mobile phone.


Sensor has two main components. Transmitter, which sends out sound waves with a frequency of 40 KHz. This frequency is above the range of human hearing. Wooden block acts as an obstacle and it reflects sound waves. Receiver acts as microphone. It processes sound waves reflected by wooden block.

Sensor calculates the distance of the wooden block from it, in centi-meters.
The Arduino processor sends this information to the Bluetooth module for further transmission to mobile phone.

Data can also be visualized in graphical form. Another app is used for this purpose.

We will pack all the components in a plastic container. This will act as a boat. Wooden blocks can be used to simulate a rough water bed.

As mentioned earlier, the sensor used for this model operates in the air medium only. We will move the sensor from outside of the aquarium for now.

You can see the profile at the bottom in this graph. Blue part is water and black part is the rockbed.

Obstacles are marked with circles. Various combinations of obstacles can be tried. Due to vibrations while moving, the bottom profile is slightly wavy. It is not flat.

Sensor sends an ultrasonic pulse out at 40kHz which travels through the air and if there is an obstacle or object, it will bounce back to the sensor. By calculating the travel time and the speed of sound, the distance is calculated.

Ultrasonic Sensors are best used in the non-contact detection like Presence of other objects,
Water Level, distance and much more.

In the next version, we will use a sensor which works in water as well.

The custom code used for this project is available for download. Please refer to the link in the description .

[ Ссылка ]


#268_EM_SonarWorkingModel


Thank You.

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