Recording Data For Post-Processing - Magellan MobileMapper CX Getting Started Manual

Recording Data for Post-Processing

There is one additional rule for optimizing MobileMapper CX
accuracy when recording rover data that will be differentially
corrected by MobileMapper Office in post-processed mode:
All features must be logged while the receiver is continuously
tracking at least 5 satellites with a PDOP less than 4 for at
least 20 minutes.
You need to record only a single "epoch" of GPS data to get a
position, but you need to record at least 20 minutes of data to
post-process it for sub-meter accuracy. All features recorded
within a 20-minute portion of a job file will be correctable to
submeter accuracy.
For example, if you record a job over a one-hour period and
lose lock on (i.e. fail to continuously track) the available GPS
satellites at Minute 20 and Minute 40, all of the features in
this job were recorded during a 20-minute period of continu-
ous GPS signal lock, and so all can potentially be post-pro-
cessed for submeter accuracy.
But if you record a 60-minute job and lose lock at Minute 20,
Minute 30 and Minute 40, any feature recorded between
Minute 20 and Minute 40 may not be sub-meter because they
were recorded during 10-minute periods of continuous satel-
lite tracking.
Without knowing a lot of other factors, it is hard to say how ac-
curate a feature recorded during a 10-minute period of con-
tinuous lock will be, but it will be more accurate than a real-
time corrected position.
IMPORTANT! Only the SBAS mode can be used while record-
ing raw data to let MobileMapper CX deliver real-time DGPS
positioning.
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