Edison may have been an asshole but was no idiot. He also said when he was very old that the biggest mistake he had made was in not respecting Tesla or his work.

The German Christian Huelsmeyer was the first to use radio waves to detect "the presence of distant metallic objects". In 1904 he demonstrated the feasibility of detecting a ship in dense fog but not its distance. He obtained a patent for his detection device in April 1904 and later a patent for a related amendment for determining the distance to the ship. He also got a British patent on September 23, 1904 for the first full radar application, which he called telemobiloscope.