Visual range and the amount of precipitation, device null wavelength in order to execute the manner which decides the type of precipitation and the aforementioned manner which combines with the visual range measurement equipment and

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus wherein various phenomena such as fog, rain, snow and the like can be discriminated satisfactorily. ;SOLUTION: A first receiver (2) is arranged so as to face a light transmitter (1). A second receiver (3) is arranged in a range at a forward scattering angle of 20 to 40°, a third receiver (4) is arranged in a range at a forward scattering angle of 70 to 120°, and a fourth receiver (5) is arranged in a range at a forward scattering angle of 140 to 150°. A modulation oscillator (15) is installed on the upstream side of the light transmitter (1). The respective receivers (2, 3, 4, 5) are connected to an electronic evaluation device (33) through postamplifiers (6, 7, 8, 9) and synchronous rectifiers (10, 11, 12, 13).;COPYRIGHT: (C)2003,JPO