ALEXANDRIA, Va., March 19 -- United States Patent no. 12,253,252, issued on March 18, was assigned to SWARM HOLDINGS LLC (Salt Lake City).
"Power filtering device" was invented by Jonathan Neil Hart (Salt Lake City), Paul Mark Michalczuk (Bainbridge Island, Wash.) and Jesse Alden Smith (Ogden, Utah).
According to the abstract* released by the U.S. Patent & Trademark Office: "An audio filtering and power extraction apparatus for filtering out audio signal and extracting power from a combined signal and direct-current power line, with an input configured to couple to a combined signal and direct-current power line, a filtering extractor system functionally coupled to the input, a DC sensing switch circuit, and a second order low-pass filter...