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GPS Accuracy
MobileMapper Pro provides 5- to 10-m autonomous accuracy
around the globe assuming the receiver is tracking five GPS
satellites 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 from
its built-in WAAS/EGNOS receiver. You must be in North
American to make use of the free WAAS signals broadcast by
the US Federal Aviation Administration. You must be in Eu-
rope to make use of the free EGNOS signal broadcast by the
European 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-based
systems such as Coast Guard beacons or your own privately
broadcast RTCM Type 1 or Type 9 corrections. Just use the se-
rial cable to connect your MobileMapper Pro to a differential
correction receiver. A "D" will appear on the MobileMapper
Pro's logging screen when the receiver detects RTCM input.
The accuracy with land-based systems is approximately the
same as with WAAS/EGNOS. However, it is possible to im-
prove accuracy by one or two decimeters if you broadcast your
own RTCM corrections while keeping the distance between
the broadcasting reference receiver and the rover receiver less
than 10 km (3 miles).
If you average positions for a point feature for a few minutes,
even better accuracy is possible.
To achieve the best
accuracy, it is impor-
tant to hold the
receiver vertical and at
eye level. This allows
the internal antenna to
pick up signals from
the GPS, WAAS and
EGNOS satellites. This
is especially true when
recording data for post-
processing.
