I have been using a Garmin 16a 5 hz and Garmin 17 in Western Ohio for several years for yield mapping. Both operate WAAS. I am within sight of 5 dofferent cell tower arrays and have not had any problem. I do loose the differential sometimes late afternoon for short periods. By the way, I have used the 16a 5 hz for sight bar work on my sprayer, and although not perfect, very acceptable. That gps with shipping was under $400. I will by another low end with the money I saved when the next generation comes out.