The new satellites, called Block III, are set to make America's GPS constellation more powerful, more reliable, and more accurate on the ground. Right now, GPS is reliable for a location fix to within ten feet of a person's actual location. Block III satellites should cut that margin of error down to within three feet. Boosted signals should also boost penetration and coverage, making receivers on the ground more accurate when under tree canopies or in so-called urban canyons where coverage is presently spotty. It should even make indoor GPS somewhat better.