Magellan GPS PROMARK X, User Manual

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Differential
ProMARK X
7-6
To give you an indication of the quality of your data collection session in
the field, the ProMARK X and ProMARK X-CM feature quality indicators.
These quality indicators represent the effective number of standard
observations that will affect how the data will process (centimeter,
submeter, and pseudorange). These
quality indicators display in the differ-
ential collection screen and increment
with each valid data observation. You
can scroll through the different quality
indicators by pressing the RIGHT AR-
ROW in the differential data collection
screen. Also, the bottom line of the
differential collection screen displays
ENTER TO STOP
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the effective number of satellites that apply for the particular session
(centimeter, submeter, and pseudorange).
Here is the criteria that the ProMARK X uses:
Centimeter— each credit represents a valid standard observation that
contains at least 5 satellites with elevation angles at more than 15
°
.
Submeter — each credit represents a valid standard observation that
contains 4 satellites with elevation angles at more than 25
°
.
Pseudorange — exch credit represents a pseudorange solution with a
PDOP of at least 2.0.
In general, with each quality indicator, any observations that are less than
the ideal as set forth above, only receive partial credit.
If you have the option, you will generally get better results by locating the
control point in an area that is similar to that of the remote. In other
words, if the remote antenna is collecting data on a flat, asphalt surface
you can obtain better results by choosing a nearby control point that is
on a similar flat, asphalt surface. This way, both points will be affected
by similar multi-path conditions.
Before collecting your centimeter or submeter differential session, be
sure to position (turn) the multi-path resistant antenna so its embedded
marker points North. This ensures that the phase centers of both
antennas at the remote and control positions are consistant. This is
important when you are collecting data for centimeter accuracy.