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ASDIC: What Is It, How It Works And How It Is Used

ASDIC stands for Anti-Submarine Detection Investigation Committee. It is an underwater detecting system developed during World War I and was used in underwater detection of large submarines and U boats. The ASDIC is also known as the Sonar in the modern world. The development and advancement in underwater detection systems is crucial in both wartime and peacetime operations. 

What is ASDIC Sonar?

ASDIC, which stands for Anti-Submarine Detection Investigation Committee, specializes in sonar technology used for underwater acoustic detection. ASDIC was initially set up during World War 1, first used in late 1918 and improved its efficiency during World War 2 times. The primary purpose of ASDIC is to detect and track submarines, which used to be a significant threat to naval troops during both World Wars. 

Unlike traditional Sonar, which is a generic term for  various types of underwater sound based detection systems. Whereas, ASDIC was specifically designed for Anti-Submarine WarFare. The development of ASDIC during World Wars played a crucial role in safeguarding the naval units.

ASDIC vs Sonar

Full FormAnti-Submarine Detection Investigation CommitteeSound Navigation and Ranging
UsagePrimarily used in World War II by the British Navy to detect submarines.Used for various purposes, including submarine detection, depth measurement, and underwater mapping.
TechnologyInitially used passive listening to detect underwater objects by listening to the echoes of sound waves.Utilizes active and passive techniques, emitting sound waves and analyzing the returning echoes.
Sound SourcePassive system, relying on ambient noise and ship noise.Active system, emits sound pulses (ping) and listens for their reflections.
FrequencyPrimarily operated at low frequencies (around 18-20 kHz).Can operate at various frequencies depending on the application, ranging from very low to high frequencies.
RangeShorter detection range compared to modern sonar systems.Can have longer detection ranges, depending on the frequency and equipment used.
AdvantagesSimple technology, difficult for submarines to detect.More versatile and adaptable for various underwater tasks.
DisadvantagesLimited range and accuracy compared to modern sonar.Can be easily detected by submarines due to active transmissions.
ASDIC vs Sonar

The Difference Between ASDIC and Sonar

To understand ASDIC better, it is important to differentiate the concept of Sonar from it. Sonar, is short for Sound Navigation and Ranging, which is a technology that uses the sound waves to detect and locate objects inside the sea water. 

ASDIC on the other hand is a specialized form of Sonar optimized to track and target submarines. It is incorporated with unique features and design elements to detect and target the submarines and U-boats. While conventional sonar systems can be used for various underwater purposes, ASDIC is designed solefully for Anti Submarine Warfare. 

How Does ASDIC work?

The Core principle of the ASDIC is really simple. It relies on the Transmission of the Sound waves into the water and the reception of the echoes on encountering any obstacle. Thats the basic overview on how ASDIC works. 

Sound Transmission

Underwater Transmitter,  often called the Transducer, which emits a burst of high frequency sound waves into the water that surrounds the device. Then these waves travel through the water medium at a known speed which is 1,481 m/s. 

Echo Reception 

When these sound waves that were emitted by the transducer encountered any object such as the submarine in the water, some of the sound waves bounces off of the object and the bounced wave was returned to the ASDIC system. 

Data Analysis

The ASDIC system analyzes the time taken for the sound waves to return and the characteristics of the returned sound wave echoes. Based on the characteristic of the returned echo, the distance of the object, its size and its speed and direction is calculated. 

Display and Interpretation

The processed data from the above step is then displayed on a screen, allowing the operators to visualize the underwater environment and any potential threats, such as the submarines. 

Applications of ASDIC

ASDIC’s primary application as mentioned before was in Anti-Submarine Warfare. During World War 2, it played an important role in the battle of the Atlantic, where the Allied forces used ASDIC-equipped ships to locate German submarines and U-Boats. This tech was important in protecting the vital supplies and ultimately leading to winning the war. 

After the war, ASDIC tech found its application in various sectors including marine research, underwater explorations and commercial shipping. The ability to map the ocean floor and locate underwater Geological features made it invaluable in many more scientific discoveries. 

In modern times, the advancements in sonar technology have made ASDIC less efficient. But the ASDIC’s legacy is that it is the primary system that laid the foundation for Underwater Detection Systems. 

Advantages of ASDIC Sonar

One of the main advantages of ASDIC sonar is its effectiveness in detecting the submarines. Even in uncontrollable harsh underwater conditions. Unlike some other SONAR systems that might struggle in the shallow or cluttered water waves, ASDIC can perform well in various conditions. 

Moreover, ASDIC’s importance in world war times cannot be undermined. Its importance during World War 2 was a critical factor in the Allied Forces Victory. It showcased the power of technology in fighting the war against submarines and its legacy lead to the further developments of the Sonar technology.

Limitations and Challenges

While ASDIC is impressive, it has its own limitations. One of the significant limitations is its depth range. ASDIC is most effective in relatively shallow water, making it less suitable for deep-sea applications. Additionally, like all sonar systems, ASDIC can be susceptible to False Positives and False Negatives, especially in places with complex acoustic properties such as canyons. 

Moreover, there are environmental concerns with the use of High Intensity sound waves used in the ASDIC sonar. These sound waves can potentially impact marine life and whales and dolphins, causing disorientation or even harm.


In conclusion,  ASDIC or Anti-Submarine Detection Investigation Committee is a specialized form of sonar tech developed during world war times for the purpose of detecting and tracking submarines. Unlike generic sonar systems, ASDIC is optimized exclusively for anti-submarine warfare, making it highly effective in detecting submarines even in challenging conditions.

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