SNIPER DETECTION

“Shot. Two o’clock. Three-hundred meters.”

These or similar words are familiar to generations of warfighters. In the past, it may have taken a few seconds, or even a few gunshots, before a shooter’s position could be ascertained.

These days, this information is communicated to warfighters almost instantaneously, sometimes by voice through an earpiece attached to a dismounted soldier or through a graphic display on a vehicle-mounted system. These kinds of capabilities are being provided by a number of sniper detection systems that have been designed and developed for use by ground forces.

The current conflicts in Afghanistan and Iraq have made personnel particularly vulnerable to sniper fire. U.S. forces face small bands of hit-and-run insurgents with endless places to hide in rural mountainous terrain or densely populated urban environments. Vehicle and environmental noise often prevent personnel from hearing the report of sniper fire or from localizing its source. They might not be aware they are under attack until they hear the ding of a round bouncing off a vehicle—or worse.

The prevalent sniper detection system used by the U.S. military, called Boomerang, was developed by Raytheon BBN Technologies in 2004 in response to an urgent request from the Defense Advanced Research Projects Agency, better known as DARPA. Boomerang is acoustic-based, meaning that it is equipped to listen through an array of microphones for the bang and crack of sniper gunfire.

The U.S. military is currently evaluating other acoustic systems, all of which process signals collected from sensors, alert users to the presence of incoming fire, and provide an indication of the direction and distance of that fire. Warfighters also are testing infrared-based systems that detect the heat signature of a weapon’s muzzle flash, systems that claim to offer a more accurate indication of the location of a shooter. These assets range from vehicle-mounted systems to soldier-worn gadgets and are increasingly being used for fixed-site perimeter protection at observation posts and forward operating bases.

Boomerang is a passive acoustic system that activates on the shock wave of a supersonic round and, if available, the muzzle blast to pinpoint the location of a hostile shooter. “Because the system focuses on the shock wave, there are no false alarms caused by extraneous noises such as door slams or backfires, and line of sight is not required,” said Mark Sherman, Raytheon BBN’s Boomerang chief.

The system has been deployed in both mobile and static environments. It has been successfully deployed on HMMWVs, mine resistant ambush protected (MRAP) vehicles, Stryker vehicles, light armored vehicles, as well as various other types of military and commercial vehicles.

The system’s sensors consist of an array of microphones mounted on a mast at one corner of a vehicle. The system has proved to work effectively on vehicles moving at speeds up to 60 mph. BBN has sold over 10,000 Boomerang systems to the U.S. military, according to Sherman.

“There has been a shift in the use of Boomerang to protect fixed-site locations,” Sherman added. “The ability to locate a shooter in an urban environment or mountainous terrain is important for self-preservation.”

Earlier this year BBN was awarded a $54 million contract to provide security against gunshots at sites in Afghanistan. The technology associated with the fixed-site system provides the location of the shooter with greater accuracy than the vehicle-mounted system, Sherman explained.

“The system installed in vehicles provides a relative ‘o’clock’ positioning of the shooter,” he said. “The fixed-site system provides precise grid coordinates. Multiple systems can be networked together and information provided to a central command location.” The fixed-site system provides an alert to users by pinpointing the location of hostile sharpshooters on a map display.

PDCue, another acoustic-based gunshot detection system developed and marketed by AAI Corp., identifies the two signatures associated with a round moving at supersonic speed: the initial muzzle blast, or bang, and the crack as the round pierces the sound barrier. Most sniper weapons fire supersonic rounds such as the 7.62 mm or .50 caliber.

“We delivered 50 PDCue systems to the U.S. Army that were deployed to Iraq,” said Michael Paturzo, managing director, business development, for AAI Test & Training. “We understand they were since moved to Afghanistan and that the Army is still evaluating the systems. We haven’t heard much more than that and we have not heard any negative feedback.”

PDCue differs from Boomerang in that it utilizes a distributed array of sensors at four separate points of a vehicle as opposed to the collocated Boomerang sensors mounted on a single corner mast. PDCue’s groups of six sensors are arrayed in four small cubes that are mounted at or below the roof line at multiple locations on a vehicle. The system uses the length and width of the vehicle as the aperture to generate target information. The system determines where the shot is coming from by measuring the different timing of the sensors in detecting the shot.

The sensors feed data to a processing unit inside the vehicle. The targeting output of PDCue is displayed graphically in the form of a bulls-eye on the vehicle-mounted tablet computer equipped with the proper software. PDCue systems have been mounted on Strykers, HMMWVs, and MRAPs, as well as on helicopters and small boats.

PDCue was recently updated so that it can be run on a vehicle-mounted Windows-based computer. “We did this to meet the Army’s preference for open architecture systems,” said Paturzo. “If you already have a PC in a vehicle running Windows for another application, you can use the same PC and don’t need a unique screen to display PDCue data. This also increases processing speed.”

Sniper detection systems also come in soldier-wearable variations. QinetiQ set out to develop a miniaturized version of a sniper detection system that was designed from the beginning to be soldier wearable. The system, called SWATS, for Soldier Wearable Acoustic Targeting System, is part of the company’s Ears family of products, which now also includes vehiclemounted systems, Ears-VMS, as well as systems for fixed locations, Ears-FSS.

SWATS is an acoustic system that uses four microphones contained in a small package measuring 20 cubic inches, including the graphic display of the shooter location. The microphones detect the bang and crack of incoming rounds.

Ears is the smallest, lightest, lowest power and lowest profile gunshot localization system available, according to Mike Halas, business development manager for the technology solutions group at QinetiQ North America, with the shoulder-worn system, SWATS, weighing less than one pound.

“SWATS has become the Army’s system of choice for soldier-wearable gunshot detection,” he said. “The military has ordered several thousand of these systems. Before long, 20,000 will be deployed in theater.”

SWATS has been integrated with the Land Warrior Program, an integrated fighting system for infantry soldiers that includes weapons systems, helmet, computer, digital and voice communications, positional and navigation systems, protective clothing, and individual equipment.

The vehicle mounted and fixed location variations of Ears were developed in collaboration with QinetiQ customers, who realized that the soldier-worn technology could be adapted to other situations. The advantage of mounting a small Ears system on a vehicle, Halas noted, is that it saves space and power, both of which are at a premium.

The Ears family of systems is built in a modular fashion so that the same sensor mounted on a soldier’s shoulder on a dismounted patrol can then be placed in the vehicle and later in a fixed location when the patrol returns to a forward operating base. “The same kit provides gunshot detection for all of these operational phases,” said Halas. “I’m pretty sure no other system moves from the body to the vehicle to the FOB as seamlessly as ours.”

Boomerang Warrior is a soldier-worn version from Raytheon BBN that provides the same shooter location technology provided by the conventional Boomerang system to individual dismounted soldiers. Boomerang Warrior is integrated into tactical vests and situational awareness systems. The user wears a small ear bud and a small display is attached to the vest. The system provides the “o’clock” position of the shooter and can work with the earpiece, the visual display, or both.

“Within one second of detection, the soldier hears an immediate alert through an ear piece and can get additional details such as azimuth, elevation and range from the wrist display,” said Sherman. “It utilizes the same technology as Boomerang to locate and announce shooter locations but is dramatically scaled down in size and weight.”

The 11-ounce Boomerang Warrior fits on a soldier’s shoulder. “It presents a very small footprint,” said Sherman. “When you do that you give up a little on performance, but it meets or exceeds all government requirements for soldier-borne systems.” Boomerang Warrior is currently undergoing U.S. military evaluations.

A system that boasts a robotic element, as well as a few more bells and whistles than its cohorts, comes from BioMimetic Systems (BMS). Dubbed RedOwl, the system was originally incorporated into an iRobot android but has since also been adapted as a soldier-wearable system. The system has been acquired by the U.S. Navy for specialized missions, but has yet to be deployed.

The robotic version listens autonomously for sniper fire. When incoming fire is detected, the robot turns toward the source and aims zoom optics and thermal optics laser illuminators on the target. “The shooter is put in light that can be seen only through night vision equipment,” said Socrates Deligeorges, chief technology officer at BMS. “That way we can light up the shooter without him actually knowing it.”

The system relies on research originally conducted at Boston University that allows the signal processors to mimic the functionality of human hearing. “The difference between our system and other acoustic systems is that our specialized processing is based on the human neural system,” said Deligeorges. “It processes the signals the same way as the brain. This nontraditional method of processing allows our system to do things other systems can’t do, particularly in noisy environments.”

Within the last year, research on the soldier-worn RedOwl system has advanced so that sensors are networked and warfighters become nodes in a network. Shooter data can be processed centrally to gain more accurate information. The system has also been integrated with command and control and situational awareness systems such as Blue Force Tracker. RedOwl will be undergoing live fire demonstrations later this year.

Another system currently being evaluated by the U.S. military in Afghanistan uses infrared technology, and not acoustic sensors, to detect, characterize and locate enemy snipers. Pete Weiland, chief engineer at Radiance Technologies, which makes the WeaponWatch system, noted that acoustic systems typically provide a direction and a distance for a shooter; the infrared sensor, which detects the heat signature of the muzzle blast, he said, is able to pinpoint the exact location of a sniper.

“An acoustic system will tell you which side of the street the shooter is located on,” said Weiland. “Infrared sensors will tell you which window he is perched at.”

One advantage of IR technology is that the sensor does not have to see a flash from a weapon nor hear the discharge of the round. It just has to pass through the sensor’s field of view. “The technology consists of a sensor camera and processor,” said Weiland. “The sensor picks up the signature of the gunfire and distinguishes that from possible false alarms. We are also able to classify the type of round such as small arms fire, RPG, or mortar.”

WeaponWatch has been tested on ground vehicles with good results, according to Weiland. U.S. special operations forces in Afghanistan have acquired dozens of WeaponWatch units for outpost perimeter protection.

“They have mounted the system on towers,” said Weiland. “WeaponWatch is good for base protection because the sensor can stare out over a wide area to pick up the flash of a weapon.” Weiland also suggested that WeaponWatch could be integrated with Boomerang, with the latter providing a warning and the former pinpointing the location of the shooter. 

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