Difference Between Radar and Sonar

Radar vs Sonar

RADAR and SONAR are both detection systems used to identify objects and their position related parameters when they are at a distance and not directly observable. RADAR stands for RAdio Detection and Ranging, and SONAR stands for SOund Navigation And Ranging. Both detection systems use the method for detection of the reflection of a transmitted signal. The type of the signal used in the system makes all the difference; RADAR uses radio waves, which are electromagnetic waves and SONAR uses acoustic or sound waves, which are mechanical waves. Variety of applications and differences in the operation of the systems are due to the restrictions posed by the properties of these waves.

More about RADAR

Radar is not an invention by a single man, but an outcome of continuous development of the radio technology by several individuals from many nations. However, the British were the first to use it in the form we see it today, that is, in WWII when the Luftwaffe deployed their raids against Britain an extensive radar network along the coast was used to detect and counter the raids.

The Transmitter of a radar system sends a radio (or microwave) pulse into the air, and part of this pulse is reflected by the objects. The reflected radio waves are captured by the receiver of the radar system. The time duration from transmission to reception of the signal is used to calculate the range (or distance), and the angle of reflected waves gives the altitude of the object. Additionally the speed of the object is calculated using the Doppler Effect. A typical radar system consists of the following components.

• A transmitter, which is used to generate radio pulses with an oscillator such as a klystron or a magnetron and a modulator to control the pulse duration.

• A wave guide that connects the transmitter and the antenna.

• A receiver to capture the returning signal. And at times when the task of the transmitter and the receiver is performed by the same antennae (or component), a duplexer is used to switch from one to the other.

Radar has a large range of applications. All the aerial and naval navigation system uses radar to obtain critical data required to determine safe route. Air traffic controllers use radar to locate the aircraft in their controlled airspace. Military uses it in the air defense systems. Marine radars are used to locate other ships and ground to avoid collisions. Meteorologists use radars to detect weather patterns in the atmosphere, such as hurricanes, tornadoes and certain gas distributions. Geologists use ground penetrating radar (a specialized variant) to map the interior of the earth and astronomers use it to determine the surface and the geometry of the nearby astronomical objects.

More about SONAR

Unlike radar, sonar is a natural method used by some animals (such as bats and sharks) for navigation. Sonar was developed before the radar and was used in WWI, to locate the submarines and mines in the sea. Acoustic location in the air was used even before radar.

Sonar uses acoustic waves (sound waves) for detection. The frequencies used for this purpose can vary from very high (ultrasonic) to very low (infrasonic). The components of a sonar system are the same as a radar system but operate in relation to sound waves.

Sonar has application in a wide variety of fields. Mainly in marine related navigation and detection, sonar is used for underwater surveillance and communication. Also, it is used for mapping underwater terrains and to observe the activity of underwater water current. In fisheries, it is used for detection of shoals of fish. It is also used by scientists, to determine the biomass of the hydro ecosystems.

What is the difference between Radar and Sonar?

• The radar uses radio waves for detection, while sonar uses sound waves (or acoustic) for detection.

• Radar usually is used in the atmosphere, while sonar is usually used underwater. However, these are not strict conditions.

• Radar has a greater range than the sonar (preferably in air).

• Radar has faster response (radio waves travel at the speed of light), while sonar is slower in response (speed of sound is low, and it depends on the properties of the medium, such as temperature, pressure and if its sea water, its salinity).