SX BLUE GPS iSXblue II+ GNSSTM, User Manual

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SXblue Series User Manual 42
1.4.5.2 General Guidelines for Sub meter GIS Field Data Collection
•
Proper antenna location is critical for sub-meter positioning. The best
location for a GPS antenna is above the head with no obstruction of the sky.
A soft hat for the precision antenna is supplied with the SXblue receiver
standard packages. In the case where the use of a security hardhat is a
must, the antenna can be mounted inside or outside the hat with Velcro type
material. For applications requiring a survey or backpack range pole, refer
to the previous subsections for mounting the Precision Antenna and the
receiver on a range pole. When less accuracy is needed, the antenna can
be shoulder-mounted (ex. on a cruising vest for some forestry work).
•
When the SXblue is first powered in a data collection session, it is preferable
to allow it to track GPS and SBAS satellites for a minimum of 5 minutes
(ideally 10 minutes) before recording any data. Here are a few reasons for
doing this:
o
A GPS receiver, with a freshly downloaded GPS almanac, will track
better under obstructed conditions like in forestry applications
o
It can take up to 5 minutes for a GPS receiver to download a
complete Ionospheric Grid from an SBAS satellite. A special feature
of the SXblue Series is its ability to extrapolate the downloaded grid
(see chapter 2)
o
With the GNSS models, SureTrack technologies enable the use of
GLONASS satellites in the code DGPS and phase RTK solution
respectively, without receiving GLONASS corrections from the
differential source (SBAS, RTK, GPS-only base station, etc). This
unique feature requires 3 to 5 minutes of tracking constant GPS
differential corrections signal.
o
For forestry applications, if SBAS visibility is marginal, it is preferable
to activate the receiver outside of forest canopy condition, let the
receiver track the SBAS signal for at least 5 minutes, then the data
collection can start
o
It takes about 2 minutes of GPS tracking for carrier phase smoothing
to be effective
o
If doing sub meter work, it is preferable to let the receiver settle (for
about 15 to 30 seconds) after a loss of position fix, prior to resume
data collection.
1.4.5.3 Basic Knowledge for RTK Field Work
•
When used in RTK applications, the Precision Antenna supplied with the
Standard package will provide with reliable cm accuracy but might present
some limitations. For base/rover configuration (rover receiving corrections
via radios or IP connection from a reference station, called a single baseline
solution) it is preferable to remain within 15 km of the reference station. As
the baseline increases, it might take a bit longer to fix the ambiguities of the
carrier phase. For typical surveying work and/or longer baseline length the