The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 19, 1987
Filed:
Jun. 13, 1985
Dieter Sodeikat, Baierbrunn, DE;
Abstract
A method and apparatus for deriving an off-course signal for an orbiting th satellite, preferably a geostationary satellite, by an earth-horizon sensor. The earth-horizon sensor operates in the infrared range and comprises, in the focal plane of an input lens, a chopper disk, which is periodically reciprocated with a determined chopper frequency (f) and which has a diameter corresponding to the image of the earth, and a detector (1) receiving the periodically interrupted radiation of opposite earth rims. The output signal of the detector is demodulated synchronously with the chopper frequency (f) and corrected with a correction signal corresponding to different temperatures of opposite earth rims (earth anomaly). In order to be able to use the earth-horizon sensor not only as a ZERO-seeking sensor, but also as an angle-measuring sensor the amplified detector output signal is additionally demodulated synchronously with the second harmonic wave of the chopper frequency (2f) thereby producing a presence signal (U.sub.p). This presence signal, or a reference signal produced from the presence signal and the amount of the corrected off-course signal (.vertline.U.sub.DO .vertline.), respectively, are used in order to draw the characteristic line of the earth-horizon sensor into the desired characteristic line of the earth-horizon sensor, also during a 'off-pointing', by controlling the amplification factor for the detector output signal, which is applicable for the instance when the line of sight of the earth-horizon sensor, which line of sight is fixed with respect to the satellite, is aligned with the earth central point.