User:216.232.18.59/stellar sensor

Stellar sensors take images of the sky and by comparing the relative positions of the stars determine its own positions based on a star catalog. The advantage of a stellar sensor is that even at medium resolution it can provide accuracy of ~10-20 arcseconds, and unlike inertial navigation it requires no initial reference point or known orientation.

Initially pioneered in the early 1970s, advancement in CCD and computing power has made star trackers very attractive for space navigation of satellites.

Star tracker consists of three major parts: Optical Head (OH), Frame Grabber (FG), and Processor Unit (PU). OH provides FG with an analog video signal. FG converts it to the digital form and stores the frame in a buffer memory accessible to PU. Apart from A/D conversion, FG carries out some other kinds of data preprocessing synchronously with the image readout.

PU implements deep imagery processing, including separation of star images, star pattern recognition, catalog handling operations, filtering, and attitude evaluation.