SONAR: Advantages and Disadvantages

This page explores the advantages and disadvantages of SONAR (SOund Navigation And Ranging).

What is SONAR?

Introduction:

• SONAR is a system used to detect objects underwater, measure water depth, and map the seafloor.

• It functions by emitting sound pulses and detecting or measuring the reflected pulses.

• SONAR locates objects by estimating the acoustic travel time and direction of arrival between the sonar sensor and the object.

• The technology is similar to radar, ultrasound, and seismic technologies.

• There are two main types of SONAR: passive and active, as shown in the figure below.

  • Passive Sonar: This type relies on acoustic noise waves radiated by the target. The SONAR system receives these acoustic signals.
  • Active Sonar: In this type, the SONAR transmits an acoustic signal that propagates towards the target (or reflector) and gets reflected. These reflected waves travel back towards the SONAR receiver. The system then estimates range and direction of arrival.

Active SONAR vs Passive SONAR

SONAR is widely used for various applications, including fish finding, seafloor imaging, seafloor mapping, finding submarines, and underwater navigation. Other types include hand-held sonar and intercept sonar. The advantages and disadvantages vary depending on the type and application. The following sections outline the typical benefits and drawbacks of generic SONAR based on its operational principles.

Benefits or Advantages of SONAR

The following are benefits and advantages of SONAR:

• It is the only effective system for finding and identifying objects in water and for determining water depth.
• It’s valuable for various water-based activities. The sound waves used by SONAR don’t attenuate as much in seawater as radar waves or light waves do.
• It’s a very accurate system.
• It’s generally not too expensive.

Drawbacks or Disadvantages of SONAR

The following are drawbacks and disadvantages of SONAR:

• The waves emitted by SONAR can interfere with marine life, threatening whales, dolphins, seals, turtles, and sea lions.
• SONAR systems can generate a lot of noise, depending on the sound levels produced.
• Acoustic waves used in SONAR are affected by sound velocity variations over depth, causing refraction of acoustic energy. Furthermore, the ocean acts as a lossy medium for acoustic waves. This can necessitate the use of high-level sound waves to compensate for the losses, which could pose a threat to humans (e.g., well divers and military personnel) and marine animals.