There are many hand-held GPS receivers you can use to acquire GPS locations. The Magellan SporTrak Pro ® delivers the convenience of a compact, lightweight design without compromising superior performance and robust functionality (Figure IIa-1). Whatever GPS unit is chosen, it is important that it be WAAS-enabled for positioning accuracy. WAAS stands for Wide Area Augmentation System and is a system of satellites and ground stations that provide GPS signal corrections. Manufacturers claim that a WAAS-capable receiver can give you a position accuracy of “better than 3 meters, 95 percent of the time.”

We compared the Sportrak® unit to the Trimble Pathfinder Pro XRV and found it quite acceptable. On average, there was a 4m difference between the same locations identified by the two receivers. The cost of the SporTrak® unit is about $250. We recommend that farmers acquire this type of GPS receiver, but if you already own a WAAS-enabled GPS unit, it will work. If we all used similar units, it would standardize our techniques and reduce learning and calibration time.