Once a project has opted to use recreational GPS technology, which receiver is used doesn’t matter, right? Wrong!! Older, cheaper receivers get confused as the transmissions from the GPS satellites are blocked by obstructions and then reappear. When doing mapping work in tree cover, only receivers with “high sensitivity” technology should be used. The term refers to a set of circuit design and firmware improvements that allow the receiver to deal with signal disruptions encountered in tree cover. At one time, the “high sensitivity” technology added about $100 to the price of a receiver. We are most familiar with the Garmin brand and it appears that the high sensitivity features are included in all their current products. There aren’t many of the old klunkers around, but it’s definitely something to watch out for.