ALEXANDRIA, Va., June 4 -- United States Patent no. 12,320,947, issued on June 3, was assigned to Minelab Electronics Pty Ltd. (Mawson Lakes, Australia).
"Metal detector" was invented by Bruce Halcro Candy (Mawson Lakes, Australia).
According to the abstract* released by the U.S. Patent & Trademark Office: "A method for detecting a target using a metal detector by producing at least two different modulated audio tones, by modulating a first audio tone with a first stereo audio modulator signal and modulating a second audio tone with a second stereo audio modulator signal; and applying at least the first audio tone to a left side of an audio stereo target indicator indicative of the target, and applying at least the second audio tone to a ...