BEL Weapon Locating Radar The BEL Weapon Locating Radar ( WLR ) is a mobile artillery locating Phased array radar developed by India . This counter - battery radar is designed to detect and track incoming artillery and rocket fire to determine the point of origin for Counter - battery fire . The WLR has been jointly developed by DRDO ' s Bangalore based laboratory , LRDE and the Government owned Bharat Electronics Limited ( BEL ) . The sub - systems have been fabricated by BEL based on the DRDO designs and delivered to LRDE for integration . History . The Indian army projected a requirement for fire - finding radars in the 1980s . As early as 1989 , the Indian Army evaluated the American AN / TPQ - 36 / 37 radars . However , these radars were not allowed to be sold , and the procurement process was stopped by the Government . In February 1995 , a Request for Proposal ( RFP ) was issued to five companies for procurement of 4 WLRs . Only Hughes ( now Raytheon ) responded to the RFP . After trials , the radar was found to not be meeting the General Staff Quality Requirements ( GSQRs ) of the Indian Army , which were found to be too stringent , and were relaxed . At the same time , it was decided to consider development of an indigenous WLR by India ' s primary defense contractor , DRDO . In September 1998 , an RFP was issued for the urgent purchase of WLRs - An / TPQ - 36 / 37 from Hughes ( USA ) , Thomson CSF ( France ) and ISKARA of ( Ukraine ) . However , the American and French radars were withheld after sanctions were imposed after the Pokhran - II Nuclear tests , and negotiations with the Ukrainian manufacturers came to no conclusion . Additionally , DRDO was not authorized to begin development of a WLR . These lacklustre efforts to obtain a WLR system were severely criticized by the Parliamentary Standing Committee on Defence . Efforts to acquire such a system intensified after the Kargil War , where the Indian Army was severely disadvantaged by its lack of firefinding radars . While the Pakistani forces were equipped with American AN / TPQ - 36 Firefinder radar s , India only had British Cymbeline mortar detecting radars , which were not suitable . Almost 80 % of Indian casualties during the war resulted from enemy artillery fire , making such a radar critical . To correct this weakness , in 2002 , the Ministry of Defence issued an RFP to five manufacturers . With the lifting of sanctions in late - 2001 , the US Government offered to sell the AN / TPQ - 37 radar to India under their Foreign Military Sales ( FMS ) programme for . 680 million each . In July 2002 , India placed a $ 200 million USD order for 12 AN / TPQ - 37 Firefinder radar s . Initially , only 8 were ordered for $ 140 million USD , but the order was later increased to 12 . The radars were integrated on BEML - manufactured Tatra truck platforms . Delivery of all 12 radars was completed in May 2007 . Concept design work on the WLR also accelerated in the aftermath of the Kargil War . The WLR project was officially sanctioned in April 2002 , with a sanctioned amount of 200 million and an estimated completion time of 40 months . The first working prototype was to be ready by April 2004 . The final project cost was $ 49 million USD . In January 2003 , an intent for procurement of 28 WLRs was placed with BEL . Design . The WLR is similar to the AN / TPQ - 37 radar in design and performance but is reportedly more user friendly . It is a passive phased array radar , derived from the Rajendra Radar ( which is the fire control radar for the Akash missile system ) . During tests of the Akash missile at Chandipur , engineers noticed the Rajendra radar was able to detect and track artillery shells being test fired at a nearby range . Based on this observation , LRDE scientists were able to adapt the Rajendra Array into the WLR . The WLR Array is an electronically - steered radar , meaning the radar antenna does not move while in operation . The radar can electronically scan a + / - 45° range of azimuths for incoming rocket , artillery and mortar fire . The radar antenna is slewable up to + / - 135° within 30 seconds , which gives the WLR the ability to quickly change its scanning sector , and provides it 360° scan capability . The Coherent TWT based transmitter of the WLR emits 40 kW of power . Tracking of the target is done with monopulse signals with Pulse compression , which improves the radar ' s LPI . The radar processors conduct real time signal processing of the received signals . The weapon locating algorithm is an adaptive algorithm based on a modified version of the Runge - Kutta method , and uses Constant false alarm rate ( CFAR ) techniques to detect the target accurately . The operator can choose the CFAR technique to be used to maximize the accuracy of information . The data is processed on a programmable digital signal processor using a modified extended Kalman filter , with two filters - one with 6 states , and another with 7 states . Clutter rejection is achieved through Moving target indication ( MTI ) , Airborne MTI ( AMTI ) and Fast Fourier Transform ( FFT ) . Information is displayed on ruggedised power PCs on a high resolution multi - mode colour display . The data is displayed in real - time and can be overlayed on a 3D digital map . The WLR can store a 100 km x 100 km size digital map for display at any time . Other modes include Plan position indicator ( PPI ) display , RHI displays , etc . Up to 99 weapon locations can be stored and tracked at any time and can be transmitted to the command centre . Operation . The WLR is designed to detect and track incoming artillery rounds , mortar and rockets and locate their launchers . In its secondary role , it can also track and observe the fall of shot from friendly guns and provide fire corrections to counter - battery fire . The detection range for large caliber artillery rounds is up to 30 km , and increases to 40 km for unguided rockets . The robust design of the radar array and algorithms allows the WLR to effectively operate even in a high density fire environment , in severe clutter and interference ( jamming ) conditions . Up to 7 targets can be tracked simultaneously . The radar can track rounds fired at both low and high angles , and at all aspect angles - from behind or towards the radar , or at an oblique angle to the array . The WLR features adaptive radar resource scheduling to increase efficiency and reliability . At a given position , the radar can scan for targets in one quadrant , encompassing a 90° sector . The array can electronically scan up to + / - 45° from its mean bearing . Additionally , for 360° coverage from a given position , the whole array can be rotated by 135° on either side within 30 seconds to quickly change the scanning sector in response to threats . Upon detecting an incoming round , the automatically acquires and classifies the threat and initiates a track sequence , while continuing to search for new targets . The incoming round ' s trajectory is tracked , and a computer program analyzes the track data and then extrapolates the round ' s point of origin . This calculated point of origin is then reported to the radar operator , thus allowing friendly artillery to direct counter - battery fire towards the enemy artillery . The WLR also allows for remote operation , and data - linking for better situational awareness at higher echelons of the command hierarchy . The data can be automatically transmitted to a command center , and can communicate with higher echelons . The radar data can also be displayed on a remote screen to protect operators from any targeted attacks on the radar . The operators can also remotely change the scanning sector . Many radars can be networked together to work in tandem and increase the accuracy and provide more information . Platform . The WLR is configured on a wheeled Tatra 8x8 truck platform . The trucks are manufactured by BEML in India under license . The WLR is designed to operate in a high - density fire environment and has all weather capability , high mobility and quick reaction time . The system is a two vehicle configuration , with the primary sensor , processors , displays and control unit on a single vehicle , and a separate power vehicle to power the radar . The radar data can also be displayed remotely . The Radar is designed to operate in harsh environments ranging from - 20 to + 55 °C , in hot and humid conditions , and can be safely stored from - 40 to + 70 °C . It can operate at high altitudes up to . Shock & vibration performance and resistance to EMI / EMC are according to international military standards . The WLR is designed for quick deployment and decamp , and can be ready for action within 30 minutes . In case of any incoming threats , the radar can be quickly moved out of the threat area . Status . A basic prototype of the WLR was first unveiled at Aero India - 2003 . The WLR was showcased at the Republic Day Parade in 2007 . User trials of the WLR began in 2005 . The Army also used WLRs to further their " shoot and scoot " doctrine using self - propelled guns and artillery to loosen up defense before an offensive onslaught into hostile territory . By mid - 2006 , the WLR was in advanced user acceptance trials and the radar was stated to be ready for production . After user trials by the Indian Army in severe electronic clutter and “ high density fire environment ” , in June 2008 , the WLR was accepted by the Indian Army . 28 units are on order , and are being manufactured by BEL . A large number of components will be sourced from the private sector , including some Commercial off - the - shelf ( COTS ) components from the international market . The WLR will eventually service the Army ' s requirement for 40 - 50 systems . Further improved versions of the WLR are being planned and designed , including longer range versions , as well as more compact variants for better operation and navigation over mountainous terrains .