Hand-held radar device detects breathing, heartbeats

Atlanta, GA--Researchers at Georgia Tech Research Institute (GTRI) have developed a hand-held radar device that records breathing movements from distances of up to 10 ft, even through doors and walls. Called the "Radar Flashlight," it can be used by police, military, and emergency personnel to detect concealed or trapped persons and remotely assess vital signs.

Encased in a housing about the size and shape of a large flashlight, the device features a 24.1 GHz transmitter that emits a 15- to 20-degree beam. A small antenna collects the reflected signal and an external signal processor analyzes the data. Principal research scientist Gene Greneker explains that movement by the target (even the small rise and fall of the chest associated with breathing) causes a Doppler shift in the frequency of the returning signal. The processor essentially subtracts the data that remains constant; data that is not eliminated is defined as the "respiration signature," and is passed to a separate display.

A variation on the flashlight may also be used to detect and analyze a human heartbeat from distances up to 30 ft. The device was developed in part to monitor the heartbeats of archers at the 1996 Olympics. (Skilled athletes reportedly improve their accuracy by sensing their own heartbeats and releasing the arrow between beats.) In this case, the semi-portable unit employs an antenna much larger than that used in the respiration monitor. The antenna incorporates a charge-coupled device which aligns the antenna with the subject's thorax.

Among other applications, the device could be used as a biometric identification tool. If a person's radar heartbeat signature is unique and stable over time, says Greneker, it could serve as a fingerprint of sorts.

Greneker is working on suppression algorithms that may reduce signal clutter, which would in turn reduce the amount of data that needs to be eliminated by the processor. GRTI is also seeking a partner to help produce a commercial prototype that would incorporate the transmitter, signal processor, and display into a lightweight unit that would sell for less than $500. For more information, contact Greneker at (770) 528-7744 or e-mail [email protected].