THE GPS NAVIGATION MESSAGE |
By mixing a locally generated sine wave at the same frequency as the received carrier after the ranging codes have been removed, the binary Navigation Message can be obtained -- see Figure 1 below. The extraction of the Navigation Message can therefore only be carried out in a code-correlating receiver, and not one that employs carrier wave "squaring" technique.
Figure 1. Recovery of the Navigation Message.
The contents of the Navigation Message, and the manner in which the data
"blocks" or "frames" are arranged is illustrated in
Figure 2 below.
Figure 2. The GPS message format and content.
Back To Chapter 3 Contents
/ Next Topic / Previous Topic
© Chris Rizos, SNAP-UNSW, 1999