Method of correcting errors in horizon sensors caused by radiance variations

摘要

A horizon sensor having a pair of adjacent infrared detectors which view the earth's horizon either statically or by scanning is provided with a second order radiance correction to reduce errors in determining the true position of the horizon due to radiance variations of the earth due to changes in latitude and seasons particularly at lower altitudes. The second order correction is empirically determined from a large number of horizon profiles, and in two illustrative examples for different types of sensors, the correction may be readily obtained from a linear function related to the peak radiance of the horizon profiles.