Military Technology: Gunshot Detectors

Here is the thing. Very few people enjoy being shot at. Sniper fire, especially, is said to be one of the most morale destroying things that soldiers can face. To make it even less fun, it can be very difficult to tell where gunshots are coming from. Difficulty goes up exponentially if the person firing the gun takes any kind of care to avoid detection. Laying down, using camouflage or concealment, firing only one shot from a location, or using a suppressor can make the task of locating a gunman very difficult to impossible. Enter the gunshot detector. They have been in use in the wonderful streets of nice communities like West Baltimore, South Chicago, East Orange, NJ and other third world communities within America for a few years. In combat, they have been mounted on vehicles such as Humvees, MRAPs, and Strykers in Iraq and Afghanistan, and have received pretty good reviews from the troops that have used them.

Boomerang System mounted on a Humvee

The first really effective gunshot detector to be used by US Forces in combat was the Boomerang, manufactured by BBN Technologies. The Boomerang gunshot detection system is a device that looks like a flower arrangement of microphones mounted on a pole. Which is what it is, really. The system uses seven linked microphones and a computer to detect and measure both the muzzle report of the weapon and the supersonic shock wave of a bullet flying through the air. As such, the Boomerang cannot reliably detect subsonic bullets, but it can ignore things that sound like a gunshot, like fireworks or even squib guns designed to imitate the sound of firearms. Each microphone detects the sound a few microseconds apart. The system then uses algorithms to determine a flight path for the bullet and extrapolate from that the origin of the shot. It takes less than one second. The system has a voice identification of the shot, giving the direction, range and distance above ground. The Boomerang also has a visual display that is like a clock surrounded by LED lights. When a shot is detected, the system will state, "Shot, 9 o'clock" and the display lights up the LED at the 9 o'clock position. The computer then visually and vocally states the range, elevation and azimuth to the target. The Boomerang system is powered by the vehicle it is attached to, and can be used while static or driving at speeds up to 50 MPH. False shot declarations are stated to be less than one per thousand hours of operation. The Boomerang system won the 2005 DARPA award for Significant Technical Achievement and the Massachusetts Innovation and Technology Exchange (MITX) "Technology Influencer of the Year Award."

Boomerang Sensor Module

By late 2003, it was clear that their was a growing insurgency in Iraq and that the US forces were in danger from asymmetric warfare. In the urban warfare encountered there, many troops could not tell they were being fired on until the rounds started hitting the vehicles and personnel. Secretary of Defense Donald Rumsfield tasked DARPA to provide a near term solution. The Boomerang program was developed out of a US DoD program. The Army and SOCOM had tested some PILAR gunshot detectors from France in early 2003, but their cost, at more than $65,000 per unit, were far too high for them to be issued in any large numbers. DARPA managers looked at the available technology and selected BBN Technologies based on their previously developed counter sniper system named "Bullet Ears" from 1997.

A new set of requirements was out together, including:

• Shooter localization to plus or minus 15 degree accuracy, and within one second of the shot
• Reliability for shot miss distances of one to 30 meters
• Ability to detect and localize fire from AK-47s and other small arms at ranges from 50 to 150 meters
• Reliable performance in urban environments with low buildings
• Operable when mounted on a vehicle moving up to 60 miles per hour on either rough terrain or highways
• Ability to withstand sand, pebbles, rain, and light foliage impacts
• Ability to deliver alert information in both a voice announcement and on an LED display
• Microphone array and electronics box must be replaceable in the field

The first prototype was developed in 65 days. Field tests in combat led to the improvement of the system into the Boomerang II and III. In 2008, the DoD completed a $73.8 million firm fixed price contract was awarded by the U.S. Army to BBN for 8,131 Boomerang Systems, spares and training services.

Since the Boomerang in particular and the whole idea of gunshot detectors was going pretty well, the Department of Defense has continued to fund and research the technology with the hopes of integrating it into the soldier of the future concepts that they have been working on since the 1980s.

The Soldier-Wearable Acoustic Targeting System (SWATS) can reportedly function as well as its larger, vehicle and building mounted systems.

Produced by QinetiQ, the SWATS is a part of the Ears Gunshot Localization System family. It weighs only 6.4-ounces and is worn on the shoulder of the soldier or Marine. It works in a 360-degree radius, isn't confused by ambient noise and can be used in a moving vehicle. The success of the system has prompted the US Army’s Rapid Equipping Force to place a $9.9 million order for the soldier-wearable model. The deployment in Iraq and Afghanistan is expected to be complete by 2012.

Gunshot detectors are not completely foolproof though, and knowing the direction that the shot(s) came from will not always lead to the enemy being killed or captured. In an ambush the nice computerized female British voice telling you that you are being shot at from multiple areas probably is not particularly helpful either. But the Boomerang and other systems like it are filling a gap that has never been filled and any warning is better than none.

Of course, whether or not the system is truly effective depends on more than if it simply does what it is supposed to. It also needs to be robust enough to continue to function in the dirty and austere battlefield conditions, it needs to be cheap enough to be fielded the right number of troops. But gunshot detectors are another technology that might very well change the way wars are fought over the next 10-25 years as technology matures and use is expanded and modified.