Are you seriously using some mathematical example (formula) created by teachers from Penn state university? Its a formula example how to solve mathematical problem not how GPS actually works. Time signal is send by EVERY GPS satellite (its actually precise ATOMIC clock time)
here is a real source Operation Guide for DAGR: 
http://webcache.googleusercontent.com/search?q=cache:WPAfxtkXAOsJ:www.i-mef.usmc.mil/external/wss/deployable_virtual_trianing_environment/dvte_handouts/gensim/tech_manuals/dagr/DAGR%2520Pocket%2520Guide.pdf+&cd;=3&hl;=en&ct;=clnk&gl;=us#47
72.185.61.209