Magellan MobileMapper - GPS Software User Manual

Contents

27GPS AccuracyMobileMapper Pro provides 5- to 10-m autonomous accuracyaround the globe assuming the receiver is tracking five GPSsatellites and the PDOP < 4 (which is almost all the time).MobileMapper Pro is also capable of providing 2- to 3-m hor-izontal accuracy using real-time differential corrections fromits built-in WAAS/EGNOS receiver. You must be in NorthAmerican to make use of the free WAAS signals broadcast bythe US Federal Aviation Administration. You must be in Eu-rope to make use of the free EGNOS signal broadcast by theEuropean Union. If you are receiving a WAAS or EGNOS sig-nal, a “W” appears on all logging screens.In addition to WAAS/EGNOS, MobileMapper Pro will automat-ically apply real-time differential corrections from land-basedsystems such as Coast Guard beacons or your own privatelybroadcast RTCM Type 1 or Type 9 corrections. Just use the se-rial cable to connect your MobileMapper Pro to a differentialcorrection receiver. A "D" will appear on the MobileMapperPro's logging screen when the receiver detects RTCM input.The accuracy with land-based systems is approximately thesame as with WAAS/EGNOS. However, it is possible to im-prove accuracy by one or two decimeters if you broadcast yourown RTCM corrections while keeping the distance betweenthe broadcasting reference receiver and the rover receiver lessthan 10 km (3 miles).If you average positions for a point feature for a few minutes,even better accuracy is possible.To achieve the bestaccuracy, it is impor-tant to hold thereceiver vertical and ateye level. This allowsthe internal antenna topick up signals fromthe GPS, WAAS andEGNOS satellites. Thisis especially true whenrecording data for post-processing.