rmhurt

I have three units that all fall within the professional grade Thales MobileMapper Pro Thales ProMark3 Thales MobileMapperCE w/ArcPad.

Most GPS units, if they are not receiving some sort of differential correction are accurate to the 10 meter range. Today, even with many commercial grade units you can acquie the WAAS differential correction signal which should put you in the 2-3 meter range. There are professional grade units that will achieve sub meter results with the WAAS or BEACON signal. A 2-3 meter professional grade unit with the ability to receive the WAAS signal is $ 1,750.00. You must also be aware that if you are receiving the WAAS signal, it is being broadcast in ITRF coordinates and most probably if you are looking for MONUMENTS OR BENCHMARKS, those values are published in NAD83/WGS84. I have been to only 2 caches and found one to be within the 2-3 meter range but the other position was off +-35 feet. When obtaining a position for a cache, make sure you have clear visibility to the sky as you can loose lock on some SV's (space vehicles) thus fruther degrading your positional accuracy. If you try to get a position under a tree, not only can you loose lock on the SV's but you can also experience high multi path when working next to a wall or building. The most important thing is to have fun!