Swathi Weapon Locating Radar

The Swathi (Very Beneficent)[4] weapon locating radar is a mobile artillery-locating, phased array radar developed by India.[5] 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.

Swathi Weapon Locating Radar
Swathi Weapon Locating Radar at Republic Day 2018
Country of originIndia
ManufacturerBharat Electronics
DesignerElectronics and Radar Development Establishment, DRDO
No. built46
TypeArtillery Locating Radar
FrequencyC band[1]
RangeArtillery → 2-30 km
Rockets → 4-80 km [2]
Mortars → 2-20 km[3]
Azimuth+/- 45° Electronic scan (Slewable Array)[1]
Elevation-5 to 75°[1]
Power40 kW
Other NamesSwathi

The WLR has been jointly developed by the Electronics and Radar Development Establishment (LRDE), a lab of the Defence Research and Development Organisation (DRDO) and Bharat Electronics Limited (BEL). The sub-systems have been fabricated by BEL based on the DRDO designs and delivered to LRDE for integration.[6]

History

The Indian army projected a requirement for fire-finding radars in the 1980s.[7] As early as 1989, the Indian Army evaluated the American AN/TPQ-36 and AN/TPQ-37 Firefinder radars. However, these radars were not allowed to be sold, and the procurement process was stopped by the Indian Government.[8] 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 meet the General Staff Quality Requirements (GSQRs) of the Indian Army, which were found to be too stringent, and the GSQRs were then relaxed. At the same time, it was decided to consider development of an indigenous WLR by India's primary defence contractor, DRDO.[9]

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 when sanctions were imposed after India's Pokhran-II nuclear weapon tests, and negotiations with the Ukrainian manufacturers came to no conclusion.[10] Additionally, DRDO was not authorised to begin development of a WLR. These lacklustre efforts to obtain a WLR system were severely criticised by the Parliamentary Standing Committee on Defence.[9]

Efforts to acquire such a system intensified after the Kargil War in 1999 where the Indian Army was severely disadvantaged by its lack of radar that could detect artillery fire. 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.[11] Almost 80% of Indian casualties during the war resulted from enemy artillery fire, making such a radar critical.[8][10]

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.[12] In July 2002, India placed a US$ 200 million order for 12 AN/TPQ-37 Firefinder radars.[13][14] Initially, only 8 were ordered for US$140 million, but the order was later increased to 12.[7] The radars were integrated on BEML Limited manufactured Tatra truck platforms.[8] Delivery of all 12 radars was completed in May 2007.[7] 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.[15] The first working prototype was to be ready by April 2004. The final project cost was US$ 49 million. In January 2003, an intent for procurement of 28 WLRs was placed with BEL.[13]

Design

The WLR is similar to the AN/TPQ-37 radar in design and performance[16] but is reportedly more user friendly.[17] It is a passive electronically scanned array radar, derived from the Rajendra Radar (which is the fire control radar for the Akash missile system).[1] 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.[8][18] 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 travelling-wave tube (TWT) based transmitter of the WLR emits 40  kilowatts of power.[1]

Tracking of the target is done with monopulse signals with pulse compression, which improves the radar's low probability of intercept (LPI) ability. 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 maximise 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 a moving target indicator (MTI), Airborne MTI (AMTI) and fast Fourier transform (FFT).[1]

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 overlaid 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.[3] Up to 99 weapon locations can be stored and tracked at any time and can be transmitted to the command centre.[1]

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.[1]

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 radar 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.[1]

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.[1]

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 analyses the track data and then extrapolates the round's point of origin. This calculated point of origin is then reported to the radar operator and can be stored up to 99 target locations with broad digital map displays thus allowing friendly artillery to direct counter-battery fire towards the enemy artillery.[1][19]

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.[1] 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.[8] The WLR is designed to operate in a high-density fire environment and has all weather capability, high mobility and quick reaction time.[20] 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.[1]

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 16,000 feet (4,900 m).[1][3] Shock and vibration performance and resistance to electromagnetic interference (EMI)/electromagnetic compatibility (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.[1]

Status

A basic prototype of the WLR was first unveiled at Aero India-2003.[20] The WLR was showcased at the Republic Day Parade in 2007.[21] 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 defence before an offensive onslaught into hostile territory.[18] By mid-2006, the WLR was in advanced user acceptance trials and the radar was stated to be ready for production.[22][23]

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.[8] 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.[8] The WLR will eventually service the Army's requirement for 40-50 systems.[24] Further improved versions of the WLR are being planned and designed,[8] including longer range versions, as well as more compact variants for better operation and navigation over mountainous terrains. The Defence Research and Development Organisation (DRDO) officially handed over the WLR Swathi to the Indian Army on 2 March 2017 for service induction. Currently, the radar is using a 'passive' array but efforts are going on to upgrade it with an 'active' array to enhance performance and reliability.[25]

Armenia had conducted trials of similar systems offered by Russia and Poland, but they gave the final nod to the Indian system. The deal is for supplying four SWATHI weapon locating radars manufactured by Bharat Electronics Limited (BEL) to Armenia. As per the agreement, India will supply four SWATHI weapon locating radars.[26]Armenia recently arrested an army Captain who was providing sensitive information about the radar to undisclosed foreign agencies for money.[27][28]

On 30 March 2023, MoD signed a contract for WLR Swathi (Plains) with Bharat Electronic Limited (BEL) at a cost of over ₹990 crore (US$120 million). Induction is planned to be completed in 24 months.[29]

Operators
Map of Swathi WLR operators in blue
 India
  • Indian Army :
    • 31 (30 MK.I & 1 MK.ll) in service.
    • 17 more (12[30] MK.l & 5 MK.ll) are on order.
 Armenia

Specifications

[1][3]

Performance
  • Range:
    • > 81 mm mortars: 2–20 km
    • > 105 mm guns: 2–30 km
    • Unguided rockets: 4–48 km [33]
  • Elevation coverage: −5 to 75°
  • Azimuth coverage: ±45° mean settable bearing
  • Slewability: ±135° within 30 seconds.
  • Targets tracking: 7 simultaneously (maximum)
  • Firing angles: Both High & Low
  • Aspect angles: 0–180°

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 × 100 km

Environmental specifications
  • Operating temperature: –20 to +55 °C
  • Storage temperature: –40 to +70 °C
  • Damp heat: 95% RH at 40 °C
  • Operational altitude: Up to 16,000 feet (4,900 m)

See also

References
  1. WLR Infoboard Archived 6 January 2009 at the Wayback Machine from DRDO, at Aero India-2007. Picture from Bharat Rakshak.
  2. "BEL receives order from Army to procure mountain variant of Weapon Locating Radar". The Indian Express. 23 June 2022.
  3. WLR Infoboard #2 Archived 6 January 2009 at the Wayback Machine from DRDO, at Aero India-2007. Picture from Bharat Rakshak.
  4. "BUR List".
  5. "DRDO Hands Over its Developed Products to Indian Army". Press Information Bureau. 2 March 2017. Release ID :158803. Archived from the original on 8 March 2017. Retrieved 7 March 2017.
  6. WLR Page Archived 23 June 2008 at the Wayback Machine on DRDO website.
  7. "India acquires 12 contracted Weapon Locating Radars". Indo-Asian News Service. 2 May 2007. Archived from the original on 5 March 2017. Retrieved 25 July 2008.
  8. Luthra, Gulshan (July 2008). "Indian Army acquiring 28 indigenous Weapon Locating Radars". India Strategic Magazine. New Delhi. Archived from the original on 21 July 2011. Retrieved 28 July 2008.
  9. Third Report of the Parliamentary Standing Committee on Defence Archived 30 November 2005 at the Wayback Machine 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."
  10. Pranab Dhal Samanta (29 September 2001). "India can now procure weapon-locating radars". The Hindu. Archived from the original on 17 November 2004. Retrieved 25 July 2008.{{cite news}}: CS1 maint: unfit URL (link)
  11. Girja Shankar Kaura (18 February 2002). "Weapon-locating radars for India soon". The Tribune. Archived from the original on 11 December 2006. Retrieved 25 July 2008.
  12. Sixteenth Report of the Parliamentary Standing Committee on Defence Archived 18 May 2011 at the Wayback Machine 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."
  13. "Weapon Locating Radar" (Press release). Press Information Bureau, GoI. 30 July 2003. Archived from the original on 5 June 2011. Retrieved 25 July 2008.
  14. Raytheon Press Release (19 April 2002). "India Signs Agreement to Buy Firefinder Weapon Locating Radar". PR Newswire. Retrieved 25 July 2008.
  15. "Manufacturing of Weapon Locating Radar". Sainik Samachar. Ministry of Defence (India). 15 June 2002. Archived from the original on 10 April 2009. Retrieved 25 July 2008..
  16. "India develops weapon-locating radar". PIB Press Release. 13 December 2004. Archived from the original on 29 October 2006. Retrieved 25 July 2008. India has developed a weapon-locating radar (WLR) similar to the AN/TPQ-37 of the US at a cost of ₹.260 million ($49 million), Defence Minister Pranab Mukherjee told the Lok Sabha 9 Dec.
  17. "Once we Partner with World Class Companies, we May have to Upgrade our Capabilities" Archived 3 August 2008 at the Wayback Machine, An Interview with H.S. Bhadoria, Director, Bangalore Complex, Bharat Electronics Ltd., Force Magazine. Retrieved 28 July 2008
  18. "BEL Weapon Locating Radars". What Is India News Service. December 2006. Archived from the original on 4 September 2008. Retrieved 25 July 2008. 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.
  19. Strakes, Jason E. "Armenia's New Swathi Radar and Defense Imports from India: Eurasian Geostrategy or Technology Interface? - PONARS Eurasia". ponarseurasia.org. Retrieved 15 March 2022.
  20. Picture of the WLR Archived 10 October 2014 at the Wayback Machine from Aero India-2003.
  21. "Republic Day 2007 - A curtain raiser" (Press release). Press Information Bureau, GoI. 25 January 2007. Archived from the original on 5 June 2011. Retrieved 25 July 2008.
  22. "India developing weapon locating radar". Bangalore: Defence India. 20 December 2005. Archived from the original on 19 March 2008. Retrieved 23 January 2008. "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.
  23. "Weapon locating radar in final evaluation stage". The Hindu. 21 December 2005. Archived from the original on 10 February 2009. Retrieved 25 July 2008. 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, customised for airborne and ground defence systems.
  24. "India to test long-range Agni missile next year". India Digest. Embassy of India in Washington. 15 January 2004. Archived from the original on 15 December 2004. Retrieved 23 January 2008. DRDO's weapon-locating radar would be in competition to fill the Indian Army's need for 40-50 such systems.
  25. "DRDO radar handed over to Army; to bring down LoC artillery fire: Parrikar". One India. 2 March 2017. Archived from the original on 10 February 2019. Retrieved 2 March 2017.
  26. "India pips Russia, Poland to secure $40 million defence deal with Armenia". businesstoday.in. March 2020. Retrieved 29 May 2020.
  27. "Armenia National Security Service exposes new case of high treason".
  28. "Armenia arrests Army captain for passing on info to foreign agency about India's radars". February 2023.
  29. "Aatmanirbhar Bharat: MoD inks over Rs 9,100 crore contracts for improved Akash Weapon System & 12 Weapon Locating Radars Swathi (Plains) for Indian Army". www.pib.gov.in. Retrieved 31 March 2023.
  30. "Aatmanirbhar Bharat: MoD inks over Rs 9,100 crore contracts for improved Akash Weapon System & 12 Weapon Locating Radars Swathi (Plains) for Indian Army". PIB India. 30 March 2023.
  31. "India pips Russia, Poland to secure $40 million defence deal to Armenia". businesstoday.in. March 2020. Retrieved 1 March 2020.
  32. "India beats Russia, Poland to bag $40 million defence deal in Europe". aninews.in. Retrieved 1 March 2020.
  33. "BEL receives order from Army to procure mountain variant of Weapon Locating Radar". The Indian Express. 23 June 2022.
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