August 28, 2005 If there’s one thing worse than having snipers shooting at you, it’s getting shot at and not knowing. That’s the bizarre situation US Forces have encountered in both Iraq and Afghanistan as they travel the vast distances in convoys, unable to tell if a bullet has just flown past amidst the noise, dust, and rumble of up to 100 war machines around them. DARPA and BBN Technologies decided to tackle this increasingly common problem and came up with the device at right. It’s called the Boomerang Mobile Shooter Detection System and alerts soldiers of incoming sniper fire to give them the opportunity to retreat to safety or return fire before they are hit. The Boomerang units attach to a vehicle and use seven small microphones, arranged like the spine of a sea urchin, to detect both the muzzle blast and the shock wave from a speeding bullet. Once a sniper's bullet is detected, Boomerang's display panel, which is located inside the vehicle, alerts soldiers through audio and visual signals that a bullet has been fired, its direction and elevation. Boomerang is currently being trialled on 50 Humvees in Iraq.
BBN is actually a technological trouble-shooter of the highest order in the world’s most technologically adept country – the company has regularly accomplished incredibly difficult technological feats across a wide range of disciplines, and is one of the rare companies on the planet that has touched something almost everyone encounters on a daily basis –the BBN technology we all know best is the current internet email system. Ray Tomlinson, a principal engineer at BBN, won the 2004 IEEE Internet Award for his vital role in the conceptualization, implementation and standardization of network e-mail. While contributing in 1971 to the design of the ARPANET host-host protocol, Mr. Tomlinson developed the first network electronic mail system. This system quickly became the driving force behind the growth of what later became the Internet. Mr. Tomlinson has contributed to the design of several network protocols, including NVT protocol, TCP and IP protocols, packet radio protocols, and multi-media electronic mail protocols. He participated in the design of a secure network communication system, and implemented the first electronic key distribution. Although his accomplishments are numerous, Mr. Tomlinson is perhaps best known as the creator of the @ protocol for addressing electronic mail.
Since its inception in 1948, BBN has been one of the premier acoustics consulting and contract research and development industrial organizations in the United States. BBN’s most notable accomplishments include designing the acoustics for the U.N. General Assembly Hall; designing development and implementing the ARPANET, forerunner of today’s internet; inventing person-to-person network e-mail; providing the acoustical analysis of the Kennedy assassination tapes; and developing the first Internet router and the first packet switch.
The Boomerang System
Okay, enough about BBN - the vehicle-mounted Boomerang sensor system identifies the origination point of hostile gunfire, in open fields and urban environments, whether static or moving, and in all weather conditions. Sensors mounted in an array at the top of a mast attached to the rear of a vehicle detect both supersonic shock waves and sound waves from the muzzle blast to accurately identify the location from which a shot is fired. Users receive simultaneous visual and auditory information on the point of fire from an LED 12-hour clock image display panel and speaker mounted inside the vehicle.
Boomerang II detects supersonic small arms fire travelling toward the vehicle for bullet trajectories that pass within close proximity to the vehicle and at maximum effective weapon ranges. Incoming fire detection and shooter position are determined and reported in less than 2 seconds. The system resets for subsequent shot detection.
False shot detections are less that one per thousand hours of system operation at vehicle speeds under 50 miles per hour. Missed shots are less than one per 500 shots at vehicle speeds under 50 miles per hour. The system is calibrated to detect the 7.62x39 mm round, which is the round fired by the AK-47 and similar small arms. This round belongs to the family of .30-caliber rifle rounds and travels supersonically when fired from a rifle. However, this calibration does not preclude the system from detecting larger and smaller rounds. In fact, the system has been tested and proven to perform successfully with 5.56 NATO and .50 caliber machine gun rounds.
The following paper is available for download at BBN and gives a full technical rundown of the Boomerang System.
The abstract for the paper reads as follows:
Boomerang is an acoustic system installed on military vehicles that is designed to detect relative shooter azimuth/range/elevation from incoming small arms fire. It performs passive acoustic detection and computer-based signal processing. Aural and visual alerts are used to 1) inform vehicle occupants that a bullet has passed within close proximity to the vehicle and 2) indicate the position of the shooter relative to the vehicle’s direction of travel. Boomerang operates when the vehicle is stationary or moving (no motion compensation) using a single, compact, mastmounted array of microphones.
The system is calibrated to detect infantry small arms. This calibration, however, does not preclude the system from detecting larger and smaller supersonic rounds. In this paper, we discuss the design, development, testing and production of 50 Boomerang I systems over a 65-day period in late 2003/early 2004. These systems were deployed during Operation Iraqi Freedom II with Marine and Army units. Feedback from operational units identified specific deficiencies and desired improvements that were incorporated into a system re-design effort, Boomerang II. The Boomerang II system has been extensively tested for performance and environmental fitness regarding RF compatibility with tactical radios (SINCGARS), heat, cold, shock and vibration.
The US Army Aberdeen Proving Grounds conducted successful RF compatibility tests, road tests and ‘live fire’ testing. Summary results of open field ‘live fire’ static tests are presented as well as performance results on a remote-controlled HMMWV operating at 45 MPH.