USPTO Grants SRC Patent for Radar That Detects Human Breathing Through Walls

WASHINGTON : In a development that could reshape modern search-and-rescue operations, urban combat tactics, and intelligence gathering, the United States Patent and Trademark Office (USPTO) has granted a new patent to SRC, Inc. for a radar system capable of detecting human breathing and heartbeats through walls, rubble, and other physical barriers.

The patent, titled “Method and Apparatus for Detecting Breathing Radar Targets,” was invented by John Dougherty, SRC’s chief systems engineer. It formally recognizes a technology that can locate stationary people by identifying minute, rhythmic biological motions that persist even when an individual is completely still and hidden from view.

The issuance of the patent provides rare technical clarity around a class of “through-barrier” sensing tools long associated with classified military and intelligence programs, marking a significant step toward broader operational deployment.

A Radar That Sees Life, Not Movement

Traditional radar systems excel at tracking motion — vehicles, aircraft or people walking across open ground. They struggle, however, when a target is stationary, particularly behind solid structures. SRC’s patented system addresses that limitation by focusing not on gross movement, but on life itself.

At the heart of the invention is micro-Doppler processing, a method that analyzes extremely small frequency shifts in reflected radar signals. These shifts are produced by involuntary biological motions such as the expansion and contraction of the chest during breathing or the subtle mechanical vibrations caused by heartbeats.

According to the patent documentation, the radar scans an enclosed space and separates the returned signals into two components: an alternating current (AC) signal representing movement-related energy, and a direct current (DC) signal representing the static background of walls, furniture or debris. By comparing energy spikes between these two signal paths, the system can determine whether a detected object is stationary clutter or a living, breathing human presence.

Targeting the Frequency of Human Life

The patented method is designed to isolate Doppler frequencies in the approximate range of 0.1 to 4 hertz — a band that corresponds closely to normal human respiration and heartbeat patterns. Signals falling within this range are further analyzed against defined thresholds, allowing the radar to classify a return as a “stationary breathing target.”

This approach enables the system to filter out environmental noise and static objects with remarkable precision. Even when a person is unconscious, immobilized, or deliberately motionless, the radar can still detect the involuntary biological rhythms that betray their presence.

Crucially, the technology does not rely on sound, heat, or visible light, making it effective in darkness, smoke-filled environments, and noisy disaster zones where other sensing tools often fail.

Designed for Through-Barrier Detection

SRC’s radar is engineered to transmit signals capable of penetrating common construction materials such as drywall, wood, brick, and certain types of concrete, as well as debris found in collapsed structures. This allows operators to scan rooms, vehicles, or buried voids from a position of safety outside the structure.

Unlike traditional moving target indicator (MTI) systems, this design is specifically optimized for detecting biologically active but physically stationary individuals — a distinction that significantly expands its operational value.

Implications for Rescue, Combat, and Intelligence

Defense analysts say the technology addresses long-standing gaps in situational awareness across both civilian and military domains.

In disaster response scenarios such as earthquakes and building collapses, rescue teams race against time to locate survivors trapped beneath rubble. Acoustic sensors can be overwhelmed by noise, while thermal cameras may struggle in extreme conditions. A radar capable of detecting breathing offers a non-invasive method to locate survivors who cannot call out or move, potentially saving lives in the critical early hours.

In urban combat and hostage rescue operations, the ability to determine whether a room or building is occupied before entry could dramatically reduce risk to soldiers and law enforcement. By revealing the presence and approximate location of individuals behind walls or doors, the system provides tactical intelligence previously unavailable without direct visual contact.

Firefighters operating in smoke-filled or high-heat environments could also benefit, particularly when thermal imaging is degraded. The radar’s focus on biological motion rather than temperature may help locate unconscious victims inside burning structures.

From an intelligence and surveillance perspective, the technology enables covert occupancy detection without placing physical sensors inside a building, offering a powerful tool for reconnaissance and counterterrorism operations.

From Patent to Battlefield  and Beyond

While SRC has not disclosed whether the system is already fielded or integrated into existing platforms, the patent suggests a maturity level suitable for operational use. The formal recognition by the USPTO may also pave the way for civilian adaptations, particularly in emergency services and infrastructure protection.

As conflicts increasingly shift toward dense urban environments and climate-driven disasters grow more frequent, technologies that can detect life where human eyes cannot see are becoming strategically critical.

With this patent, SRC has secured intellectual ownership over a capability that blurs the line between radar sensing and biological detection — a reminder that in modern warfare and disaster response, information about who is present can be as decisive as firepower itself.