Linear shift Feedback registers

As PN codes (Or I suppose techinically pseudo random codes) are the heart of any ranging system it would be a good place to start with how to generate them.

the following wiki is useful as it has a nice animation of a linear shift feedback register working.

http://en.wikipedia.org/wiki/Linear_feedback_shift_register

Don't know what sort of generator galileo is using. hopefully that will be in a later post.