Select the right GPS signal

摘要

What you want to do should affect your choice of receiver. When you're ready to produce yield maps or vary seeding rates on the go, your first question is: Which GPS (global positioning system) signal should I use? "Ask yourself about your needs," emphasizes Dan Ess, a Purdue University extension ag engineer. "If you just want to monitor crop yields, that's one thing. But if you want to vary inputs or use GPS for guidance, those applications demand more accuracy." Technically, you're choosing a DGPS(differentially-corrected) signal, Ess notes. In the beginning, GPS signals were scrambled by the U.S. government. The government has since unscrambled signals, but most experts contend the raw signal is still not accurate enough for precision farming.Today, most GPS ag users rely on either U.S. Coast Guard beacon signals, commercial satellite services or the new WAAS (wide-area augmentation system).