Navigation system

Abstract

Abstract PURPOSE:To improve position measurement precision by controlling the output of an antenna which have directivity independently in >=4 directions covering all horizontal directions. CONSTITUTION:An antenna which is so constituted that beams of antennas 1 and 3 are set in the moving direction of a moving body and beams from antennas 2 and 4 are set at right angles to the moving direction is installed on the moving body. Then, RF-IF conversion, frequency reverse spreading, and demodulation are carried out by a GPS receiver 6 by using outputs of the antennas 1-4 and the position and time of the moving body are calculated by a device 7 which calculates the position and moving direction of the moving body. When the position and moving direction of the moving body are known, satellites which can be seen from the moving body and their directions are found by a controller 9 on the basis of information obtained by a GPS satellite track computer 8. For example, when a satellite 31 is seen in the beam direction of the antenna 2, a multipath is reflected by a building and enters the beam of the antenna 4. For the purpose, when an antenna switch 5 is controlled by the controller 9 to acquire a satellite 3, the beam output of the antenna 2 is led out and inputted to a receiver 6. Thus, the signal of the multipath is removed.

Inventors

• 👤 Hisao Iwasaki
• 👤 久雄 岩崎

Bibliographic Details