New Delhi: Defence Minister Rajnath Singh Tuesday laid the foundation stone of a 2,900-acre Very Low Frequency (VLF) station for the Navy at the Damagundam Reserve Forest site, Pudur Mandal, Vikarabad, Telangana.
The defence minister said the station would help India secure its maritime interests. It will also ensure secure and real-time communication of Navy ships and submarines with the command centres of the forces, he added.
The VLF station will support the underwater operations of India’s submarines, especially nuclear ones, by providing secure communication. VLF stations use wavelengths that penetrate deep into the salt water of oceans, reaching submarines that stay underwater. The need for VLF stations increased after India recently started operating two ballistic nuclear missile submarines (SSBNs), INS Arihant and INS Arighat.
The Navy commissioned INS Arighat last month. Additionally, Aridhaman, a third nuclear submarine launched in 2021, will most likely be commissioned in 2025. India is also now pursuing a programme to build two nuclear powered submarines (SSNs). Eventually, India will operate a total of six SSNs. Nuclear submarines, which stay underwater, communicate differently than ships and conventional submarines.
In January this year, the Telangana government transferred 1.174 hectares of forest land for the project, which has taken approximately Rs 3,200 crore to complete.
How VLF stations help submarines communicate
A conventional submarine periodically comes to the periscope depth to charge batteries and get positional updates and information from the shore through the communication antenna.
However, a submarine is a weapon of stealth and every time it comes to the periscope depth, it becomes vulnerable to detection by enemy radars or helicopters.
Submarines have no option but to come up for oxygen to charge their batteries, or if their navigation safety is damaged, to get a sense of the area. Submarines usually communicate their positions to the shore authorities only when they come up for battery charging.
A nuclear submarine uses nuclear propulsion, whereas a conventional submarine uses diesel. Unlike nuclear submarines, conventional submarines, if not fitted with Air Independent Propulsion (AIP), can be vulnerable since AIP prolongs the stay of conventional submarines underwater.
Communicating with an underwater nuclear submarine is more of a challenge. Unlike conventional submarines, nuclear-propelled submarines need not come up for charging batteries every day. Technically, it can stay underwater indefinitely.
Considering this feature, nuclear submarines are the ultimate weapon of stealth. These stay underwater, cut off from the rest of the world. However, the VLF and ELF (Extremely Low Frequency) technologies become essential for communicating with these underwater submarines. VLF and ELF waves reach a certain depth below water from where the submarine can receive the communication.
Another advantage of ELF and VLF stations is that they travel widely. For instance, a station in India can send a message to submarines in the water near the US.
However, the volume of information sent through ELF and VLF is far less when compared to High Frequency (HF) and Very High Frequency. However, ELF and VLF enable global communication and travel faster than HF/VHF.
ELF is considered far more advanced than the VLF technology, which India currently has. According to Army veterans ThePrint contacted, India’s next step should be constructing ELF stations. Apart from the new station, India has a VLF facility in Tirunelveli.
The VLF stations are specially for communicating with nuclear submarines, but such stations can also communicate with underwater conventional submarines.
A submarine communicates when on the surface, at periscope depth, or underwater. It either has a communication buoy or an antenna trailing it. The trail antenna receives the VLF/ELF communication that penetrates the water. Surface ships can also receive VLF and ELF communication but are more dependent and comfortable using HF/VHF.
(Edited by Madhurita Goswami)