The original PCAS technology was developed in 1999 by Zane Hovey, a pilot and flight instructor, who also patented a portable ADS-b version as well. Through this technology, transponder-equipped aircraft are detected and ranged, and the altitude is decoded. PCAS G4 technology has advanced to the point that highly accurate range, relative altitude, and 45 degree direction can be accurately detected in a portable cockpit device. PCAS gained notoriety with the growing popular TV series The Aviators (TV series) as a sponsor, and specifically in episode 6 airing on both PBS and the Discovery Channel Network.