What’s Your Signature!

Signature information is extremely sensitive. Therefore, we need an all Indian team. The aims must be to develop enabling technologies to reduce the signature of ships

Indian Navy, Indian Navy Day Feature

By Abhishek Jain

Why This Article?

We love cliches and as an author of articles in defence I wish I could create one in my name – don’t discuss Policy but Physics. Since, we cannot become a superpower by buying our wayout; we will need design capabilities that are contemporary. One such field that is now becoming important is detection of enemy ships, making mines capable of differentiating friend and foe (or target and innocent), and designing our ship with lesser signature. What I wish to emphasize today is the management of signature. Radar signature is quite well known but there are many other types of signature and unfortunately, they are coupled with one affecting the other in some way.

How Many?

When designing a ship, we need to take care of signatures that are (a) Radar (b) Infrared (c) Electromagnetic/ Magnetic (d) Pressure (e) Acoustic. When not trained properly, I did not know that earth magnetic field can cause a low frequency signature in ships and there were methods like degaussing to nullify its effects as far back as WW-II. Other signature considerations like pure visibility to naked eye are not a concern for this article.

Design Principle


Another cliché – at the base of any science is mathematics. From the literature survey I saw that major ship designers have national programmes for development of mathematical models for ship signature. Consider this sample equation below for the calculation of Green function for estimation of pressure signature of ship in 3D domain. The scary looking equation is actually solved using panel methods – considered a simpler method for the very few people who create such software.

The management of signature is very important. Radar signature is quite well known but there are many other types of signature and unfortunately, they are coupled with one affecting the other in some way

Not only mathematics, but we will also need many experimental facilities to find out if our maths is good enough. This will be a major investment and can be followed up once we have made our Math perfect.
There is, however, a question – can we not just buy the Math to cut short the time for development of our ships. In my opinion three reasons prevent this (a) It may not be available for sale or usually prohibitively expensive (b) Buying is never equal to absorbing (c) It may not fit our needs. Even if initially it looks like reinventing the wheel, we need to invest in these mathematical technologies. Can we create a state of the art without developing the base?

Efforts Worldwide?

Most countries have their own efforts in signature management where they own the IP and know-why. I wish to particularly point out about a Canadian programme for signature management RIMPASSE (Radar, Infrared, Electro Magnetic, Pressure and Acoustics Ship Signature Experiments). A programme that started with a technical international workshop. It concluded that there was no advanced signature management system in existence, and one was needed.

What follows is worth emulating. A system level approach was identified where all the signatures were to be treated as interdisciplinary subjects with one having bearing on the other. Every year workshops were done to identify gaps and plan further action or projects.


Radar Cross Section (RCS) is most important due to multiple radars and passive electro-optic sensors. Huge resources have been invested in superstructure shaping, invention of radar absorbing materials or making ship out of composite to avoid magnetic signature. Shaping is decided in collaboration with hydrodynamics (hull resistance) and helideck operations department (air wake issues). French are developing MOCEM software that directly gives SAR images of ship with known shape. This means we know how ship is seen from patrol aircraft or satellite even before it is made! One area that needs focus is corrosion signature management that is extremely low frequency electromagnetics – not the same as RCS but underlying simulation technology as similar.

The By-product?

What follows is worth emulating. A system level approach was identified where all the signatures were to be treated as interdisciplinary subjects with one having bearing on the other

These will not be stand-alone technologies and will help in other programmes. Captor mines differentiate between targets using acoustic signature technologies and not explode on useless targets. Mines like Stonefish have computerised fuse for pressure, magnetic and acoustic signatures detection. The possibilities are endless, I will not be surprised if tomorrow we see an AI based mine that can positively identify targets, communicate with parent ship and effectively destroy targets.

Where are We?

One area that needs focus is corrosion signature management that is extremely low frequency electromagnetic – not the same as RCS but underlying simulation technology as similar

I believe we are not far behind. RIMPASSE just ended in 2017, MOCEM is under development for newer features and USA has their own programmes. We have iDEX challenge for reduction of RCS of ship. Effort is going on to reduce acoustic signature using raft mounting. This is one area where I personally feel we can catch up at least in the math. Making facilities will take some more time but can be started right now. Defence Testing Infrastructure Scheme (DTIS) can take measurement of signatures as a priority item like it has taken for the UAVs.

What to do?

Again a cliché – we need a systems approach. Like Germany-Netherland we need an agency like Centre for Ship Signature Management (CSSM). This agency can be crafted out of naval officers as leaders, DRDO scientists, PSU and Private Shipyards, MSMEs and academic institutes. Signature information is extremely sensitive, so we need an all Indian team. The aims must be to develop enabling technologies to reduce the signature of ships. Since nothing works without mission mode, one ship on the drawing board can be used as a test case where these technologies will be tested and validated. Indian CSSM must work with other ship design teams to realise working ships. Let’s get to technical work.

-The author is Vice President, Strategic Partnership, Zeus Numerix Pvt Ltd. He was one of the 10 innovators to meet US Defense Secretary, and is also a Winner of Lockheed Martin Innovation Award and various other awards. The views expressed are personal and do not necessarily reflect the views of Raksha Anirveda

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