Navigation system

摘要

Directional transmitters are used for air navigation in order to determine the position of aircraft, which directional transmitters are operated at different frequencies and are evaluated by on-board receivers. In the case of small aircraft which have wandered off course and have come into turbulence, it is difficult to determine their position using the known systems, particularly if the altitude is less than 3000 ft. In order to avoid these disadvantages, transmitters (2, 3, 4) are installed on the ground, which each produce upwardly directed focused radiation (5, 6, 7) which covers a horizontal rectangular area at a predetermined height (8). These areas abut one another at the predetermined height (8). All the transmitters (2, 3, 4) operate at the same frequency, but with different identifiers. <IMAGE>