By Atul Chandra
The Indian Air Force is charged with the responsibility of defending the countries airspace and is now in the process of modernising and upgrading its Air Defence (AD) network. Providing a capable and responsive AD network has lead to the creation of the ‘Integrated Air Command & Control System’ (IACCS), which when completed will link various airborne platforms, ground-and space-based sensors, Surface to Air Missile (SAM) systems, air bases and enable them to exchange secure voice, data and real-time pictures through an ‘Operational Data Link’ (ODL). The IAF is expected to have the IACCS operational in a few years’ time. At present, the IAF has a host of modern radar systems being inducted or due for induction in the near future, quite a few have been upgraded and possess a useful residual life while many of the older radars are due to be phased out. The challenge for the IAF is to integrate the older generation equipment with the newer ones coming in, training of manpower and maintenance crews.
Bharat Electronics Limited (BEL) has played a crucial role in the delivery and maintenance of air surveillance radars to the Indian armed forces and these include the older THD 1955, PSM-33, TRS 2215, TC Reporter radars and later INDRA MK-I & INDRA MK-II and Tactical Surveillance Radar supplied for AD applications. At present BEL supplies the Low Level Transportable Radar (LLTR), Rohini, Surveillance Radar Equipment (SRE) and 3D Tactical Control Radar (3D CAR). A new addition is the Arudhra radar (OEM Elta Systems), being inducted to replace the ageing TRS-2215 and PSM-33 radars. It offers detection ranges in excess of 300 kilometers and will be an important cog of the IACCS. Apart from this, the IAF has already placed orders for 19 LLTR from Thales with a range of 180 km to augment its low level coverage. Thales and Bharat Electronics Ltd (BEL) will supply 19 Ground Smarter GS-100 LLTR’s to the IAF. Under the TOT deal, Thales will build the initial six radars at its Limours facility, southwest of Paris and BEL will build the remaining radars in India.
The design challenges faced for AD Radars are adaptive signal processing, beam switching, Real-time Radar Data Processing, threat evaluation, ballistic algorithms for fire control, weapon assignment, state-of-the-art Electronically Steerable Array Antenna for 3D target detection, multi-sensor tracking, solid state transmitters, Digital Receivers, state-of-art MW components & super components, Transmit Receive Modules (TRM), IFF MK-XII with S mode, etc. While some of these technologies have been realised through BEL’s in-house development efforts, quite a few have been realised in association with Defence Research Development Organisation (DRDO) labs. The critical factors in radar for AD applications are reaction times, state-of-the-art Electronic Counter-Countermeasures (ECCM) features, low altitude target detection, tracking accuracy, multi-target tracking, Electro Optic options for passive tracking, mobility and deployment in-action time.
Some of the features used in AD Radars to counter electronic counter measures are frequency agility, waveform agility, pulse compression, staggered PRFs, side lobe blanking, analysis of home on jammers, omni directional jamming & directional jamming and least jammed frequency selection. Also, providing passive tracking facility using electro-optic systems is common while designing AD radars. The current generation Radars from BEL have been developed to cue in on targets based on information received from interfaces like target data receivers or equivalents. Also, BEL is supporting the armed forces with indigenously developed C4I systems for net-centric operations. The company has set up state-of-the-art facilities for R&D and manufacturing of microwaves super-components like TR modules, phase shifters, power devices, etc at two locations: one at its Bangalore Unit and the other at its Ghaziabad Unit. The Microwave Component Facility at Bangalore Unit is now being upgraded for future load and technologies.
ADS RADARS IN SERVICE
Indian Doppler Radar
INDRA MK-I & INDRA MK-II: INDRA MK-I has an L-Band, 2D radar capable of target acquisition with a range of 40 km and was delivered by BEL from 1992-1995. The radar is housed in two wheeled vehicles. Some of the main features are automated Track While Scan (TWS), integrated IFF and high scan rate for high speed target detection. INDRA MK-II, is a variant of the INDRA radar for ground controlled interception of targets by the IAF with 90 km range and was manufactured by BEL from 1997-2001. The radar uses pulse compression for detection of low flying aircrafts in heavy ground clutter with high range resolution and has good ECCM capabilities. The INDRA radar was developed by Electronics and Radar Development Establishment (LRDE) Bangalore.
3D Medium Range
Rohini: is a ground-based mechanically scanning S-Band pulse Doppler medium range (185 km) surveillance radar to detect and track air targets even under hostile EW operational environment. The radar scans the air space 360° in Azimuth and 30° in elevation up to 18 km height. The flexible architecture is a reliable and adaptable technology for multiple applications early warning for air defence weapon system, air defence sensor at airbases. The radar has advanced technologies like digital receiver, programmable signal processor providing high resolution, accuracy, response and information availability. The software controlled high-speed digital technologies offer real time configuration to the operational crew. The advanced software algorithms, multiple high speed processors, and state-of-the-art digital technologies have made the radar an effective and user friendly sensor providing 24x7 airspace awareness to the Commanders during peace and war time. The radar is packaged on two high mobility TATRA vehicles to meet operational and battlefield mobility requirements. 2x125 kVA generators are housed on a third TATRA vehicle. The radar, which is easy to operate, mobile, transportable by air, rail and road, can be deployed and decamped in less than 30 minutes. The first radars entered service in 2008 and the IAF has total orders for 37 radars with deliveries are underway and a final number of 100 expected to be built for the IAF.
Rajendra Radar: The Rajendra, multifunction phased array radar, is the primary sensor at battery level for Akash SAM system — The radar has the capability to perform extensive search, track multiple targets and missiles, and to command and guide own multiple missile concurrently. The radar system, mounted on two tracked vehicles — Battery Level Radar (BLR) and Battery Control Center (BCC), for all types of operations with matching mobility. The radar has the flexibility to work in Group or Autonomous mode, and it has UHF communication facility to support Group mode of operation.
3D-CAR: 3-Dimensional Central Acquisition Radar, is a medium range surveillance radar for Akash at Group level, with high mobility and excellent high and low level coverage. The radar provides range, azimuth and height information of the targets, enabling better designation of targets for follow up actions. This radar was designed to function in multiple roles with a potential to meet the surveillance needs of all the three Services. The radar is packaged in a KOLOS TATRA two-vehicle configuration with a vehicle carrying diesel generator sets. The vehicle housing the antenna and most of the sensor subsystems is called the Radar Sensor Vehicle (RSV). The second vehicle called the Data Center Vehicle (DCV) houses the radar consoles, data processor unit and communication unit. Variants of the radar have been developed for Army Air Defence, air force and navy for air space surveillance applications.
3D TCR: 3D Tactical Control Radar is a Tatra VVL mounted, mobile stand-alone medium range, all weather 3D surveillance Radar for detection and identification of aerial targets. Pertinent data can be collected at Target Data Receiver (TDR), 20 kms away from the Radar. The radar operates in S-band and is capable of Track-While-Scan (TWS) of airborne targets up to 90 km for fighter aircrafts and 65 km for UAVs, subject to radar horizon. The antenna is mechanically rotated in azimuth to provide 360 degree and 50 degree elevation coverage up to 10 km height.
Apart from these some of the older radars still in service are, the THD-1955 which is 3D long range (450 km) S Band radar, manufactured by BEL from 1974-1992. The radar has been upgraded by Thales and continues to see service. The PSM-33 Mk 1 is a 3D, S band, mobile medium range (250 km) radar and supplied by BEL from 1983-1988. The upgraded PSM-33 Mk 2 for long range (440-510 km) air surveillance was delivered from 1985-1991. BEL has also been instrumental in the upgrading, maintenance and obsolescence management of many legacy radars in service with the Indian armed forces with some having been in service for more than four decades. This Unit (Ghaziabad) in collaboration with Thomson CSF, started manufacture of S-Band 3-D Radar with a range of 230 nautical miles for air surveillance in 1974 and the PSM 33, a 3-D Mobile Radar, was manufactured in 1983. The Flycatcher Radar, air defence weapon control radar, was manufactured in collaboration with HSA and supplied to the army in 1987. Legacy Radars that are being given product support services are USFM Radar, Flycatcher Radar, THD 1955, TRS 2215 and PSM Radar. Product support services such as spares supply, upgrade kits, form & fit replacements, repairs and overhauling support, automatic test facilities, training and stocking critical components to provide end-of-life support are being offered to ensure the reliability and continued performance of these radars in the field. There have been quite a few interests expressed for AD Radars from countries like Malaysia, Indonesia and others and BEL is closely following up with potential customers.
In December 2007 SELEX Sistemi Integrati was awarded a 52 million Euro contract for the delivery of 13 air traffic control radar systems to the IAF consisting of 13 ATCR33 S primary radars, 13 SIR S secondary radars, and 52 consoles CDS 2000 for the equipment of the respective control centres. Previously the company won a tender for the delivery of 12 Air Traffic Control systems to the Indian Air Force, in accordance to a new Surveillance Radar Element (SRE) programme. The supply consisted of eight turn-key systems and additional equipment. The contract with the Indian Air Force has included a cooperation for the industrial know how transfer towards Bharat Electronics Ltd. to assemble other five fixed systems and three transportable systems.