They are referring to integer ambiguity resolution, which is the final step in getting a dual-frequency differential GPS position down to centimeter accuracy.
This [1] is a good explanation. It does require a GPS receiver capable of carrier phase tracking, which your cell phone isn't capable of. The cheapest I've seen is this uBlox [2].
This [1] is a good explanation. It does require a GPS receiver capable of carrier phase tracking, which your cell phone isn't capable of. The cheapest I've seen is this uBlox [2].
[1] http://www.navipedia.net/index.php/Carrier_Phase_Ambiguity_F...
[2] https://shop-america.u-blox.com/en/usd/3~130~AMERICAS/Positi...