11. Instead, Aebi had a sextant for celestial navigation and a radio direction finder . 12. The radio direction finder is the earliest form of radio navigation. 13. The boat also supports the Simrad TD-L1550 VHF-FM radio direction finder . 14. Some ships also received a Huff-Duff radio direction finder on a short mainmast. 15. Lear developed radio direction finders , autopilots, and the first fully automatic aircraft landing system. 16. There are variants, among the classes, of a radar antenna, interferometric direction finder , COMINT receiver. 17. Two distinguishing external features of the UC-43 are the circular automatic direction finder R-985 engine. 18. This consisted of a set of tracking stations using HF / DF radio direction finders . 19. Anything but the crudest direction finders , however, were expensive luxuries for small-boat handlers until quite recently. 20. He invented a series of naval instruments, including the direction finder called " Ullrings peileskive ".
