Dark current compensation of pixels tracking stars several times

摘要

In an optical sensor arrangement which is for use on a spacecraft in tracking an objective star and comprises an optical sensor comprising pixels for receiving starlight from the star to produce pixel output signals with or without dark currents, such dark currents are compensated for by a device which comprises (A) a projecting unit for projecting a real image of at least one star on a certain number of pixels, nine pixels in the illustrated simple example, to make the optical sensor produce sensor output signals a few times, such as five times, and (B) a processor unit for processing the processor output signals into compensating data for use in compensating for the dark currents. Preferably, the processor unit comprises a pixel address generator (31), a data memory (49), and a digital processor (51).