Magellan ProMark 3 Spezifikationen PDF herunterladen (Seite 134)

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5. Accuracy

Autonomous GPS, SBAS & DGPS Modes

ProMark3 provides autonomous 3-meter accuracy all around

the globe assuming the receiver is tracking five GPS satellites

and the PDOP < 4 (which is almost all the time).

ProMark3 is also capable of providing 50- to 70-cm horizontal

accuracy using real-time differential corrections from its built-

in SBAS receiver. You must be in North America to make use

of the free WAAS signals broadcast by the US Federal Aviation

Administration. You must be in Europe to make use of the free

EGNOS signal broadcast by the European Union. If you are us

ing the Mobile Mapping function and SBAS signals are re-

ceived, a “W” will appear on all logging screens (after the

number of received satellites; see page 125).

In addition to SBAS, ProMark3 can apply real-time differen-

tial corrections (DGPS) from land-based systems such as

Coast Guards beacons or your own privately broadcast RTCM

Type 1 or Type 9 corrections. Just use the serial cable to con

nect your ProMark3 to a differential correction receiver. A

"DGPS.." will appear on the ProMark3's Position screen when

the receiver detects RTCM input.

The accuracy with land-based systems is approximately the

same as with SBAS. However, it is possible to improve accu

racy by one or two decimeters if you broadcast your own RTCM

corrections while keeping the distance between the broad-

casting 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 accu-

racy, it is important to hold

the receiver at an angle of

45 degrees from horizon-

tal. 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-pro-

cessing.

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Magellan ProMark 3 Spezifikationen Seite 134