Determination of coverage by infra-red tracking instrument - with measurement of visual range and water content of air

摘要

The optical visual range and the water content of the air are measured and these results, together with the assumed target data and sensitivity of the infra-red instrument, are used by an electronic computer to determine the coverage of the infra-red instrument. To determine the absolute water content of the air the relative water content and the air temperature are measured. An electrical resistance dependent on humidity can be used to determine the water content of the air. The coverage of the infra-red instrument is determined by atmospheric absorption and atmospheric dispersion.