Without much calculations, it seems two 24 bit values would also fit longitude and latitude, when limiting to 4 decimals in decimal degrees. That would only give one an accuracy of 11 meters, but in my above quote someone claims (emphasis mine):
- The fourth decimal place is worth up to 11 m: it can identify a parcel of land. It is comparable to the typical accuracy of an uncorrected GPS unit with no interference.
- The fifth decimal place is worth up to 1.1 m: it distinguish trees from each other. Accuracy to this level with commercial GPS units can only be achieved with differential correction.
Are you using a more precise GPS, or do GPS units actually give more accurate results than assumed above? (Or is the above quote wrong? Wikipedia gives the same numbers, but without any claims.)
(Note that I am no expert; just trying to help documenting this.)