Frequencies measurements and DF or direction finder azimuths. Instead, Aebi had a sextant for celestial navigation and a radio direction finder. When closer may we avail ourselves of your direction finder. Did not have a direction finder capability or a Y control interface. The ship also received a HF/DF radio direction finder mounted on a pole mainmast. But the base's radio direction finder only had a single loop antenna. There are variants, among the classes, of a radar antenna, interferometric direction finder, COMINT receiver. For example, Francis Hubbard's sonar direction finder patent filed in 1921. Like a conventional compass, a luopan is a direction finder. Some ships also received a Huff-Duff radio direction finder on a short mainmast. The first system of radio navigation was the "Radio Direction Finder", or RDF. Automatic direction finder; an asterisk by the name means there is no DME module present. "Radio direction finding", "radio direction finder", or "RDF", was once the primary aviation navigational aid.