Wednesday, July 28, 2021

AIRCRAFT SELF-PROTECTION THROUGH SELF-RELIANCE

by Air Marshal SBP Sinha (r.)

Air Marshal SBP Sinha (r.), DRDO – Chair

Today’s aerial combat largely encompasses Beyond Visual Range (BVR) Air-to-Air Missiles (AAM), Surface-to-Air Missiles (SAM) and Air-to-Surface weapons that rely on Electro-Magnetic (EM) sensors and seekers for detection, acquisition, identification and tracking of targets and also for guidance of missiles and weapons. Reliance on EM spectrum makes such sensors, seekers, missiles and weapons vulnerable to Electronic Warfare (EW). EW helps in the attempt to ensure unrestricted use of EM spectrum by friendly forces while denying its use to the adversary. EW includes detection, interception, analysis, manipulation and suppression of EM signals through jamming, disruption and deception.

BVR AAM and SAM pose very serious threat to military aircraft and, therefore, their survivability in such contested combat environment assumes paramount importance. Aircraft can only be safeguarded by providing them requisite EW armour consisting of cutting-edge Self-Protection Suite (SPS). EW incorporates very complex and niche technologies that are shrouded in secrecy and denial regimes. Airborne EW systems face greater design challenges brought about due to space and volume constraints within an aircraft coupled with limitations of electrical power and cooling capacities available on-board an aircraft. Further, each EW systems on-board an aircraft has to be appropriately designed and integrated with the aircraft avionics and other on-board EW systems to prevent electronic fratricide within the aircraft. To make India Atmanirbhar (self-reliant) in the very complex and secretive EW field, Defence Research &Development Organisation (DRDO)along with Indian Air Force (IAF) has developed a range of state-of-the-art EW systems that not only protect aircraft but also ensure higher mission success rate. 

Most aircraft and helicopters operated by Indian Armed Forces are imported with some of them also being licence manufactured by HAL through Transfer of Technology (ToT). Mirage 2000, C-17, C-130, Chinook, Apache and Rafale were inducted with fully integrated SPS. Most other aircraft were later equipped with imported and/or indigenous EW systems after their induction. Pilots need to be provided real-time tactical situational awareness about likely and emerging threats, both from the surface and in the air. Most SAM systems and fighters use radar to detect, acquire, identify and track airborne targets and for guiding missiles to the target; therefore, Radar Warning Receiver (RWR) is the most crucial asset on-board an aircraft to warn pilots of evolving and emerging threats. RWR intercepts and identifies airborne and surface-based search, acquisition, tracking and missile guidance radars and provides audio warnings and visual display of threats to the pilot along with the operating mode of each radar viz search mode, track mode or missile launched through easy to interpret coloured alpha-numeric symbols. 

Modern aircraft are also equipped with Missile Approach Warning System (MAWS) that warn the pilots about missile(s) launched on them, missile’s direction of approach and the time left for the missile to impact the aircraft. Both RWR and MAWS help pilots to assess threats in real-time and initiate timely and appropriate tactical action and manoeuvre to defeat the threatening radar or missile. Most aircraft are also equipped with Counter Measures Dispensing System (CMDS) to dispense Chaff for passive deception of radars and Infra-Red (IR) flares to lure away heat seeking missiles. DRDO is developing Chaff and Infra-Red Flare cartridges in the effort towards import substitution. To counter missile guidance and fighter radars, aircraft are equipped with Self-Protection Jammer (SPJ) that could either be installed internally or carried externally in a pod.  

In the beginning of 21st century, DRDO had developed Tempest EW suite consisting of Tranquil RWR and SPJ for the MiG-27 fighters, which retired in December 2019. Tarang the next version of DRDO developed RWR is installed on MiG-21 BISON fighters and many other aircraft of IAF and Indian Navy. DRDO has further improved capabilities of the indigenous RWR installed on Su-30 MKI by employing advanced technologies, signal processor and algorithms for achieving higher frequency coverage and much higher pulse handling capacity. The RWR of Su-30 MKI is also designed to cue CMDS and SPJ for self-protection and cue Anti-Radiation Missiles (ARM) for attack against surface radars. Tejas LCA is equipped with indigenous EW systems. DRDO developed internal Radar Warning Jammer (RWJ), a smart combination of RWR and SPJ, has been installed on MiG-29 fighters during their recent upgrade and the same is being installed on Jaguar fighters during their ongoing upgrade.

Technological advances have led to more sophisticated radars that use complex intra-pulse characteristics with increased duty-cycle and reduced transmission power, which makes them difficult to detect and are, therefore, called Low Probability of Intercept (LPI) radars. To cope up with the threat posed by LPI radars, DRDO has developed state-of-the-art Digital RWR having digital receivers that leverage advances in  analog-to-digital converters and digital signal processing techniques to provide excellent sensitivity, selectivity and wideband instantaneous bandwidth at the same time making the detection process more versatile, flexible and powerful, which enables the RWR to detect even the most complex LPI radars.

A compact state-of-the-art Unified EW Systems (UEWS), a smart combination of internally mounted RWR and SPJ, has been successfully developed by DRDO for fighter aircraft. It consists of a core processor supported by advanced digital receiver, Digital Radio Frequency Memory (DRFM) in conjunction with advanced solid state trans-receive unit, active phased array and microwave power modules to provide all round azimuth coverage and high accuracy direction-finding capability for detection, acquisition, identification, jamming, cueing of ARM and CMDS. The core processor of the system uses state-of-the-art technologies to meet simultaneous requirement of instantaneous wide-band reception for 100 % probability of intercept for the RWR as well as narrow band capability with very high accuracies along with digital Electronic Counter Measure (ECM) technique generators for the SPJ to suppress all types of guidance and fighter radars. UEWS will be installed on Tejas Mk-2, a 4.5 generation fighter, and Advanced Medium Combat Aircraft (AMCA), the Indian Fifth Generation Fighter Aircraft (FGFA). DRDO is also developing state-of-the-art podded jammers for fighters, both for self-protection and offensive jamming. These powerful jammers will incorporate ultra-wide band digital receiver, DRFM, active phased arrays for reception and jamming with accurate direction estimation.

Dual-Colour IR MAWS, indigenously developed by DRDO will be installed on Tejas Mk-2 and AMCA to provide spherical coverage around the fighters for autonomous detection and tracking of multiple missile threats and display of real-time threat scenario in the cockpit to help the pilot initiate tactical action to defeat missile(s). Advanced dual-colour IR sensors of the MAWS help in better threat detection even against background clutter with minimal false alarm. The MAWS will be integrated with the CMDS for dispensing chaff and IR flares appropriately as per detected threat(s). 

Targeting enemy radars is vital component of Destruction/Suppression of Enemy’s Air Defence (D/SEAD) campaign executed to weaken adversary’s air defence capability. DRDO and IAF are flight-testing a state-of-the-art Passive Homing Head (PHH) seeker for ARM capable of locking-on to enemy emitter’s transmission and accurately guiding the ARM to the emitter. PHH uses fast scanning receivers in both wide-open and narrow bands to provide very high sensitivity, wide frequency coverage with accurate direction-finding capability both in azimuth and elevation. PHH is designed to interface with RWR and mission computer of the fighter carrying the ARM, before its launch.  

Electronic Surveillance, a crucial intelligence gathering activity, is conducted on 24×7 basis to create and monitor adversary’s Electronic Order of Battle, which helps confirm the combat potential and capabilities of the adversary while simultaneously collating intercepted radar signals in the emitter database and analysing them to help programme EW systems. Electronic Surveillance Measures (ESM) includes Electronic Intelligence (Elint) activities carried out to gather information on electronic emitters while Communication Intelligence (Comint) activities carried out to intercept and monitor communication and gather real-time vital information. ESM also provides critical inputs for planning route, EW tactics and force packaging for offensive fighter missions. 

IAF currently operates indigenous DRDO developed Ground Based Mobile Electronic Systems (GBMES) for ESM on 24 x 7 basis. Highly sensitive Elint receivers of GBMES detect, intercept, identify, analyse and locate all types of surface and airborne radars across the entire radar operating bandwidth. GBMES is capable of finger printing and locating radars with accuracy better than 500 m. Comint receivers of GBMES search, monitor record and identify direction of communication over a very broad frequency range. DRDO is also developing light-weight Elint system for MALE UAV with wide frequency coverage and accurate direction-finding capability along with light-weight Comint system with both search and monitoring capabilities with accurate direction-finding. 

An integrated RWR-ESM-SPS system comprising of ultra-wideband RWR-ESM, MAWS and CMDS is indigenously developed by DRDO specifically for the Airborne Early Warning & Control (AEW&C) aircraft. RWR and ESM functions are carried out simultaneously wherein RWR retains its very high probability of intercept across its entire operational band through wideband multi-bit digital receivers while the ESM is gathered through highly sensitive narrowband multi-bit digital receivers. The RWR-ESM combine provides good directional accuracy. The ESM system on-board Netra AEW&C aircraft enables airborne ESM and a case is in process to obtain approval for converting two Airbus 320 aircraft into ESM platforms. MAWS provide spherical coverage around the entire AEW&C aircraft for autonomous detection and tracking of missile threats and displaying real-time threat scenario in the cockpit. RWR-ESM and MAWS are integrated with the CMDS for dispensing chaff and IR flares appropriately as per the detected threat. 

With very humble beginnings in the field of EW starting with 2nd generation RWR and SPJ at the beginning of the century, DRDO today has developed technologies to provide state-of-the-art EW systems for all types of aircraft and has successfully developed EW systems capable of equipping and protecting 4th and 5th generation fighters.IAF has wholeheartedly supported the development programme for indigenous EW technologies and has been part of the team throughout this long period of hard work and iterative design evolution. Success of the indigenous EW programme is a collaborative effort of Defence Electronic Research Laboratory (DLRL) and Combat Aircraft Systems Development &Integration Centre (CASDIC),erstwhile Defence Avionics Research Establishment (DARE), of DRDO as Design Agencies and Aircraft & System Testing Establishment (ASTE), Software Development Institute (SDI) and Electronic Warfare Range (EWR) of IAF who have been part of the design process of all EW systems, their integration on aircraft, testing and performance validation both on the ground and in the air. 

India is taking major strides towards design, development and manufacture of increasing number of indigenous fighters and military helicopters. State-of-the-art EW Self Protection Suites developed by DRDO will provide the requisite EW armour to these indigenous fighters and helicopters. Most importantly, India will develop its own set of Original Equipment Manufacturers (OEM) in the very competitive and secretive EW field manufacturing state-of-the-art RWR, MAWS, SPJ, ground based and airborne ESM systems and a variety of chaff and infra-red flare cartridges. The dedicated and joint efforts of DRDO and IAF has helped India building indigenous technological capabilities in the very complex EW field, which will contribute immensely towards the Atmanirbhar Bharat and the Make in India campaigns of the government of India.

About the author: Air Marshal SBP Sinha (r.) is former Deputy Chief of Air Staff & Air Officer Commanding-in Chief of Central Air Command. He currently holds the DRDO Chair (Prof MGK Menon Chair)

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