BEL Weapon Locating Radar

BEL Weapon Locating Radar

Infobox Radar
name = Weapon Locating Radar

caption = A scale model of the WLR. The array is at its maximum slew setting of 125o.
country = IND
introdate =
number = 28 on order
type = Artillery Locating Radar
frequency = C band
range = Artillery = 2 - 30 km
Rockets = 4 - 40 km
Mortars = 2 - 20 km
altitude =
diameter =
azimuth = +/- 45º Electronic scan (Slewable Array)
elevation = -5 to 75º
precision =
power = 40 kW

The Weapon Locating Radar (WLR) is a mobile artillery locating Phased array radar developed by India. The 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. [ [ WLR Page] on DRDO website.]


The Indian army projected a requirement for fire-finding radars in the 1980s.cite news | title = India acquires 12 contracted Weapon Locating Radars | url = | publisher = Indo-Asian News Service | date = 2 May 2007 | accessdate = 2008-07-25 ] 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 Ukranian manufacturers came to no conclusion.cite news | author = Pranab Dhal Samanta | title = India can now procure weapon-locating radars | url = | publisher = The Hindu | date = 29 September 2001 | accessdate = 2008-07-25 ] 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. [ Third Report of the Parliamentary Standing Committee on Defence] of the 13th Lok Sabha for the year 1999-2000 (PDF). pp 18-19. The Committee commented, "The Committee is seriously concerned by the degree of seeming casualness shown by the Defence Ministry in this regard. The Committee desires that the Government should take immediate steps to equip the Army with this Radar."]

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 radars, India only had British Cymbeline mortar detecting radars, which were not suitable. [cite news | author = Girja Shankar Kaura | title = Weapon-locating radars for India soon | url = | publisher = The Tribune | date = 18 February 2002 | accessdate = 2008-07-25 ] 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 Rs. 68 Crores each. [ Sixteenth Report of the Parliamentary Standing Committee on Defence] of the 13th Lok Sabha for the year 2002-03 (PDF). pp 23-24. The Committee commented, "The Committee are not satisfied with the reply of the Ministry of Defence that acquisition of Weapon Locating Radar(WLR) will take three years. Three years is a long period. In view of the grave security threat emanating from across the borders, immediate steps should be taken to procure WLR."] In July 2002, India placed a $200 million USD order for 12 AN/TPQ-37 Firefinder radars.cite press release | title = Weapon Locating Radar | publisher = Press Information Bureau, GoI | date = 30 July 2003 | url = | accessdate = 2008-07-25 ] [cite news | authorlink = Raytheon | author = Raytheon Press Release | title = India Signs Agreement to Buy Firefinder Weapon Locating Radar | url =,+200 | publisher = PRNewswire | date = 19 April 2002 | accessdate = 2008-07-25 ] 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 Rs. 20 Crores and an estimated completion time of 40 months. [cite news | title = Manufacturing of Weapon Locating Radar | url = | work = Sainik Samachar | publisher = Ministry of Defence (India) | date = 15 June 2002 | accessdate = 2008-07-25 .] The first working prototype was to be ready by April 2004. The final project cost was $49 million USD.Fact|date=July 2008 In January 2003, an intent for procurement of 28 WLRs was placed with BEL.


The WLR is similar to the AN/TPQ-37 radar in design and performance [cite news | title = India develops weapon-locating radar | url = | publisher = PIB Press Release | date = December 13 2004 | accessdate = 2008-07-25 | quote = India has developed a weapon-locating radar (WLR) similar to the AN/TPQ-37 of the US at a cost of Rs.260 million ($49 million), Defence Minister Pranab Mukherjee told the Lok Sabha Dec 9. ] but is reportedly more user friendly. [ [ "Once we Partner with World Class Companies, we May have to Upgrade our Capabilities"] , An Interview with H.S. Bhadoria, Director, Bangalore Complex, Bharat Electronics Ltd., "Force Magazine". Retrieved 28 July 2008] 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.cite news | first = Gulshan | last = Luthra | title = Indian Army acquiring 28 indigenous Weapon Locating Radars | url = | work = India Strategic Magazine | publisher = | location = New Delhi | date = July 2008 | accessdate = 2008-07-28 | quote = ] cite news | title = BEL Weapon Locating Radars | url = | publisher = What Is India News Service | date = December 2006 | accessdate = 2008-07-25 | quote = The new radar is based on the Rajendra-phased radar system that is already deployed in the Indian armed forces after engineers accidentally noticed during an anti-missile Akash missile test, that the Rajendra system could detect and track artillery shells. ] 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 +/-45º range of azimuths for incoming rocket, artillery and mortar fire. The radar antenna is slewable up to +/-135º within 30 seconds, which gives the WLR the ability to quickly change its scanning sector, and provides it 360o 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.


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. [ WLR Infoboard] from DRDO, at Aero India-2007. Picture from Bharat Rakshak.]

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 90o sector. The array can electronically scan upto +/-45o from its mean bearing. Additionally, for 360o coverage from a given position, the whole array can be rotated by 135o 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.


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 +55oC, in hot and humid conditions, and can be safely stored from -40 to +70oC. It can operate at high altitudes up to ft to m|16000|addr=yes. [ WLR Infoboard #2] from DRDO, at Aero India-2007. Picture from Bharat Rakshak.] Shock & vibration performance and resistance to EMI/EMC are according to international MIL 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.


A basic prototype of the WLR was first unveiled at Aero India-2003. [ Picture of the WLR] from Aero India-2003.] The WLR was showcased at the Republic Day Parade in 2007. [cite press release | title = Republic Day 2007 - A curtain raiser | publisher = Press Information Bureau, GoI | date = 25 January 2007 | url = | accessdate = 2008-07-25 ] 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. [cite news | title = India developing weapon locating radar | url = | publisher = Defence India | location = Bangalore | date = 20 December 2005 | accessdate = 2008-01-23 | quote = "It (weapon locating radar) is in the final stage of evaluation. Once evaluation is complete, we will deliver it to armed forces," chairman and managing director of BEL, Y Gopala Rao, told reporters. ] [cite news | author = Staff Reporter | title = Weapon locating radar in final evaluation stage | url = | publisher = The Hindu | date = 21 December 2005 | accessdate = 2008-07-25 | quote = Electronics and Radar Development Establishment (LRDE) and Bharat Electronics Limited are in the process of developing a weapon-locating radar, similar to the phased array Rajendra radar system, customized for airborne and ground defence systems. ]

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. [cite news | title = India to test long-range Agni missile next year | url = | work = India Digest | publisher = Embassy of India in Washington | date = 15 January 2004 | accessdate = 2008-01-23 | quote = DRDO's weapon-locating radar would be in competition to fill the Indian Army's need for 40-50 such 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.



* Range:
** >81 mm Mortars: 2-20 km
** >105 mm Guns: 2-30 km
** Unguided Rockets: 4-40 km
* Elevation Coverage: -5 to 75o
* Azimuth Coverage: +/- 45o mean settable bearing
* Slewability: +/- 135o within 30 seconds.
* Targets Tracking: 7 simultaneously (maximum)
* Firing angles: Both High & Low
* Aspect Angles: 0-180o

Technical Specifications

* Instrumented Range: 50 km
* Frequency Band: C band
* Probability of:
** Detection: 0.9
** False Alarm: 10-6
* Weapon Locations: 99 stored (maximum)
* Digital Map Storage: 100 x 100 km

Environmental Specifications

* Operating Temperature: -20 to +55oC
* Storage Temperature: -40 to +70oC
* Damp Heat: 95% RH at 40oC
* Operational Altitude: Up to ft to m|16000|addr=yes


External links

* [ Weapon Locating Radar] on DRDO website.
* [ WLR Poster from DRDO]
* [ Picture of the WLR] from Aero India-2003.
* cite news
author = Bharat Verma
title = How DRDO failed India's military
url =
publisher = Rediff News India
date = January 15 2008
accessdate = 2008-01-23
quote = DRDO scuttled a contract that was on the verge of being signed by India in 1997 for the import of a Weapon Locating Radar as the latter promised to produce it indigenously within two years.

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