Reutech staring array radar takes LEDS to new level
Written by Leon Engelbrecht -
Reutech Radar Systems (RRS) says its new frequency modulated continuous wave (FMCW) staring array radar can detect a rocket propelled grenade (RPG) launch within 5.2 milliseconds (ms) and can provide an accurate track within 14.3ms. A millisecond is 1000th of a second and a RPG, fired at 20 metres, takes roughly 187 to impact.
Similar staring array technology forms the core of the radar systems supporting the US Navy’s Aegis and the US Army’s Patriot air defence complexes.
Pic: The CV90 sporting LEDS 150. Note the staring array radars at the front corners and the two high speed directed launchers containing multispectrals smoke and Mongoose missiles to the rear of the remote weapon station.
The cost of developing this technology in South Africa is not known, but RRS was awarded a R643 970 contract in July “to demonstrate a frequency modulated continuous wave ranging radar concept.” RRS last month said it has been working on staring arrays for the “past three years.”
Colonel Cobus van der Merwe (Retired), SAAB Electronic Defense Systems’ Product Manager for Land Self-Protection Systems told a recent precision weapons solutions conference that with the radar his company’s Land Electronic Defense Systems (LEDS) can detect a RPG within 5ms and calculate whether the RPG will hit or miss the carrier vehicle within a further 10ms. The active defence controller then determines the validity of the threat within a further 10ms before taking less than 50ms to compute an intercept. It then takes 10ms to launch and a further 50ms for the “effects deployment”.
RRS’ Peter Bradshaw in a separate presentation at the South African Precision Weapon Solutions Conference held at the Africa Aerospace and Defence (AAD) exhibition in Cape Town two weeks ago, added that 5.2ms for first detection amounted to a “worst-case scenario” for the radar. He added that once detected and confirmed, track updates were given every 1.3ms.
Van der Merwe avered that intercepts require precise calculation in four dimensions. The Denel Dynamics Mongoose munition “has a defined kill basket determined by fuzing, the effective radius of the warhead and the time to self-destruct.” Angular accuracy has to be within .25 of a degree, range accuracy within 50mm, X and Y axis positional accuracy within 500mm and launch timing accuracy within 10ms. On-target timing accuracy is even more acute if the basket is to be placed over the projectile in space and time: a result better than 125 microseconds (125 millionths of one second) is required.
The basic LEDS 50 warns the crew of a vehicle fitted with the system that they are in the beam of a laser. The system can deal with up to eight threats simultaneously, while providing analysis on the nature of the threat based on the spectral band used. LEDS 100 adds jammers and decoys, while LEDS 150 adds the Mongoose 1 counter-munition. LEDS 100 confuses enemy weapons operators and incoming rounds by deploying multispectral smoke in their line of sight or flight, hiding the target vehicle. The smoke and an optional infrared jammer interfere with the acquisition and/or tracking, ranging, launching or guidance of a hostile weapon. LEDS 150 destroys incoming RPG rounds or launched as close as 20m from the carrier vehicle with the Mongoose projectiles, allowing it to intercept rounds fired “from across the street”.
Van der Merwe showed his audience further evolutions of LEDS and Mongoose are on the way. LEDS 200 will be able to defeat multi-band seekers and LEDS 300 kinetic energy and “stand-off attack” weapons. LEDS 200 will rapidly deploy a multispectral coating that provides effective signature management against tri-band (CCD, IR, millimetre-wave radar) threats – and – also extinguishes fires. The latter will be a very useful feature against attacks from “petrol bombs” (“Molotov cocktails)”. Janes in June 2008 reported from he Eurosatory exhibition in Paris that LEDS 300 would expand the system’s capability to counter kinetic energy “long rod” and smart standoff threats. The concept was “tested successfully … in South Africa [in 2007] and is scheduled to be ready for operations in 2012.”
The current ballistic Mongoose 1 typically defeats an RPG-7 within roughly 6m of the carrier vehicle as the about 135ms required for the intercept process translates into 14m of range for a RPG-7 fired at 20m. While comforting to the specific vehicle’s crew this is disconcerting and likely fatal to own dismounted infantry accompanying the vehicle. A proposed guided Mongoose 2 and -3 will take the intercept envelope to 50m and a Mongoose 4 to beyond 300m.
Pic: The Mongoose detonates a PG-7 durig trials. Note the ring detonation.
To further limit friendly casualties, the Mongoose’s warhead is designed to detonate in a flat ring pattern. To limit the firing of the incoming RPG’s warhead, which would create the very armour penetrating “jet” the system is seeking to prevent, the Mongoose detonates a shaped charge in the immediate proximity of the incoming round, striking it in the side, resulting in a blast pattern that is parallel to the line of flight and leaving the detonator unfired.
RRS says the FMCW 3-dimensional radar that makes the intercepts possible was developed “over the past three years” and contains no moving parts. It combines “simple antennas” and “simple hardware” to provide the means for highly accurate detection and tracking of small, fast moving projectiles against complex clutter backgrounds. “The ability to discriminate between targets of varying velocities is achieved by the inherent high Doppler resolution of staring array systems,” RRS said in a media statement released separate from the conference. “A prototype sensor was recently integrated within a point defence system in field trials, where exceptional short-range performance against test projectiles was proven.”
The RRS release was somewhat coy, however. The AAD show daily reported the system – featuring the radar – “was selected as the baseline protection system for the Piranha V” from General Dynamics European Land Systems (formerly MOWAG). The BAE Systems Global Combat Systems (formerly Hägglunds) CV90 Armadillo was also depicted fitted with the LEDS with staring array radars fitted to the corners of the vehicle.
Van der Merwe added that the staring array radar can also be used for missile warning in the naval environment, tracking and detecting “flying targets for gun fire control”, mortar baseplate location, measuring the fall of shot and for instrumentation. Staring array radars can also be used as gapfillers in the surveillance environment.