It should be the same as with GPS. I can't remember the exact details since my study is quite some time ago. But in principal GPS (and most likely also Galileo)

It should be the same as with GPS. I can't remember the exact details since my study is quite some time ago. But in principal GPS (and most likely also Galileo) works by correlating in the incoming signal with a locally generated one. The transmitted sequences and basically look like noise in the spectrum. You can only decode them with their counterparts. For professional (and military use) other sequences are generated and transmitted in parallel (could be on other frequencies). These are longer and therefore allow decoding with a higher precision. But you have to be aware of the code to be able to use those signals. There some info written on the web, but for details you need to be aware of lots of signal theory: https://en.wikipedia.org/wiki/GPS_signals https://en.wikipedia.org/wiki/GPS_signals http://www.navipedia.net/index.php/Correlators http://www.navipedia.net/index.php/Correlators