differential correction

The correction process used to improve the accuracy (to less than 100 m/~330 ft) of a GPS signal by using a stationary GPS receiver whose location is know. The second known receiver computes the error in signal by comparing the true distance from the satellites to the GPS measured distance. An uncorrected WAAS GPS signal will be accurate to about 50 yards. A corrected signal can be accurate to within 1-5 feet. The corrected signal may be transmitted to the tractor, combine or other equipment that corrects the proper location through differential processing. There are four common ways to transmit a correction signal from the known base station to the farm implement: 1. A dedicated AM transmitter that is located on a U.S Coast Guard tower located near coastal and inland waterways, which has a range of 100-250 miles; 2. A separate, private corporation satellite to send the corrected signal (OmniSTAR, RACAL), which has worldwide coverage; 3. Piggyback the correction signal on a commercial FM radio station frequency (DCI, ACCQPOINT), that has a range of 30-40 miles; or 4. WAAS (Wide Angle Augmentation System) developed for the Federal Aviation Administration (FAA) which has US coverage.

Authorization Path: 2.5.6.4.25.0