Using The ProMark 3 for Centimeter Accuracy
by: Jon Aschenbach
The ProMark 3 (PM3) survey receiver is Magellan s biggest seller. When you
compare price, ease of use, and functionality, it s easy to see why. The PM3 s can
provide centimeter accuracy with regular consistency.
We are seeing more and more people using the PM3 s because they want something better than sub-meter GPS accuracy. This is especially true in situations where elevation
accuracy is important. A sub-meter GPS unit only provides
1 to 2 meters of vertical accuracy. The PM3 can provide
vertical accuracy in the range of 1 to 3 centimeters.
The general procedure to use a set of PM3 s is to place one
over a known position in an open sky setting. The other
PM3 acts as the rover, collecting static points or stop and
go collection.
The base PM3 unit is always set up first on a tripod set preTwo ProMark 3 s with Antennas on the
cisely over a known point. If a known point is not available, the Initialization bar
user place the PM3 anywhere and it will compute a position accurate to a meter or less. The rover data would be centimeter accurate relative to the base position.
To start a data collection operation, the user initialize with both
the base station unit and the rover next to each other. The two antennas are placed on an initialization bar with both receivers running for 5 minutes. At this point in time, the rover antenna is removed from the initialization bar and put on the range pole. The
rover can now rove around collecting static shots or it can do a
stop and go data collection. Static points only take about 15 secTribrach with optical plummet for use
onds to achieve centimeter accuracy.
with the ProMark 3 Base Unit.
Magellan s unique BLADE technology allows the PM3 to
take advantage of WAAS satellites to speed up initialization and make for a more robust solution.
Baseline distance between the rover and the base unit is limited to about six miles (10km). Beyond
that distance the accuracy potential drops off to decimeter levels (10 centimeters).
With these units there is no quicker way to bring control to your project whether the baseline
is 1/2 mile or 6 miles. No line of sight is needed between the two units. Simply have
the two receivers collect data at the same time, and then post process the data on your computer.
In well under a half day, you can set several control points on your project from up to six
miles away.
(Continued on the next page)
The base station s data and the rover data is downloaded to the GNSS Solutions software for post
processing. This process is very easy and involves simply telling the software which unit was the
base station and what coordinates to use for the base station position. Then simply click on process
and adjust and let it do its thing.
The GNSS Solutions software is very robust. In addition to doing a
post processing on your data, it provides a map, allows exporting
data to a variety of formats.
Specifications of the ProMark 3:
GNSS Characteristics:
14 parallel channels
Integrated real-time (WAAS, EGNOS)
Protocol: NMEA0183
Update rate: 1 Hz
Accuracy Specifications
Static Survey Performance:
Horizontal: 0.005 m + 1 ppm
Vertical: 0.01 m + 2 ppm
Azimuth: < 1 arc second
Kinematic Survey Performance
Horizontal: 0.012 m + 2.50 ppm
Vertical: 0.015 m + 2.50 ppm
Recommended Initializer Bar Occupation: 5 minutes
Real Time Performance
SBAS (WAAS,EGNOS) (rms)
Accuracy: Horizontal: <1 m
Size and Weight:
Receiver Dimensions: 7.7 x 4.6 x 1.8
Unit: 1.05 pounds
Antenna: 1.00 pounds
GNSS Solutions Software
Jon Aschenbach collecting data using a ProMark 3 rover unit.
Contact Jon Aschenbach at 503-707-6236 for more information.
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Resource Supply, LLC
11607 SW Winter Lake Drive
Tigard, OR 97223
503-521-0888
Jon s cell: 503-707-6236
Fax: 503-536-6869
www.resourcesupplyllc.com
Email: [email protected]
(Copyright 2009 by Resource Supply, LLC)