Detect Gunfire Threats for Grid Resilience

ShotSpotter for Perimeters is an acoustic gunshot detection system designed to protect substations and other critical infrastructure facilities from inbound gunfire threats.  The system detects, locates, and verifies gunshots directed at a protected site and delivers alerts within seconds.

Sensors deployed along the facility perimeter detect acoustic signatures generated by firearm discharge, including the muzzle blast (produced by all firearms) and the bullet shockwave (also known as an N-wave), produced by supersonic projectiles. The system measures the arrival time and direction of both N-waves and muzzle blasts and calculates the location of the shooter using the available information.  Classifiers based on machine learning are used to distinguish gunshots from other impulsive noises.  Verified alerts are delivered within seconds.

An N-wave is the characteristic shockwave produced by a projectile traveling faster than the speed of sound (supersonic).  When a supersonic bullet passes near a sensor, it produces a rapid spike in air pressure followed immediately by a sharp drop creating a waveform that resembles the letter “N”.  This distinct acoustic signature allows the system to confidently identify gunfire directed toward the facility.

N-waves are produced by firearms that discharge supersonic ammunition, which includes:

• Most centerfire rifle rounds (e.g., AR-15 style rifles, hunting rifles)
• Many common handgun calibers (e.g., 9mm, .40 S&W, .45 ACP, depending on ammunition type)

Weapons firing subsonic ammunition (such as certain suppressed or specialty rounds) do not produce an N-wave, though they still generate a muzzle blast that may be detectable.

Yes. The presence and direction of the N-wave allows the system to distinguish gunfire directed at the facility from hunters in surrounding rural areas, activity at distant shooting ranges, or other unrelated impulsive noises.  Only verified incidents directed at the protected site generate alerts.

The system calculates shooter location using angle-of-arrival analysis across multiple sensors.  Directional accuracy is highly reliable, with any variance typically occurring in distance from the facility rather than bearing.

Human-verified alerts are typically delivered in less than 60 seconds from the time of the shooting.

Substations and other grid assets are vulnerable to gunfire from outside the fence line. Traditional security measures such as fencing and cameras do not detect inbound ballistic threats that could severely damage equipment, disrupt operations and depending on type of facility, threaten life.  ShotSpotter for Perimeters closes this detection gap by providing early warning of gunfire directed at the facility, enabling faster inspection and response.

Every alert includes the calculated shooter location displayed in relation to the protected facility.  This immediately narrows inspection to the side and zone most likely affected, allowing personnel to concentrate inspection efforts in a defined area rather than searching the entire facility.
The system may also provide additional directional insight that further refines the likely path of fire and potential impact zone.  Together, this information accelerates damage assessment, supports faster stabilization, and reduces overall recovery time.

Yes. ShotSpotter for Perimeters has an API that can integrate with many camera systems, Security Operations Centers (SOC), drone platforms, and other monitoring systems. This allows rapid visual verification of the area identified in the alert.

By closing the gap between attack and awareness, the system enables:

• Faster damage assessment
• Targeted inspection
• Reduced outage duration
• Improved incident documentation
• Better protection of high-value assets

Traditional ShotSpotter deployments focus on detecting and locating gunfire within urban areas to support law enforcement response.
ShotSpotter for Perimeters is purpose-built for critical infrastructure protection, with perimeter-based sensor deployment and threat detection focused specifically on inbound gunfire directed at protected assets.