They not only have better receivers than in our phones, they have an entirely separate signal they can use- P-code (https://en.wikipedia.org/wiki/GPS_signals#Pr

They not only have better receivers than in our phones, they have an entirely separate signal they can use- P-code (https://en.wikipedia.org/wiki/GPS_signals#Precision_code https://en.wikipedia.org/wiki/GPS_signals#Precision_code). It's encrypted, so it's not for civilian use, and the ability to look at two signals of different frequency at the same time means that they have been able to have much more robust GPS than civilians for awhile.