Javad TRIUMPH-LS Quick Start Manual - page 24
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Collect
Collect
RTK Verification and Validation
It is very important that you read and understand the
information about RTK Verification and Validation
contained in this manual.
Verify Settings Screen - Recommended Settings for Multipath
Environments
When located in difficult environments and under tree
canopy, all GNSS receivers are prone to give bad fixed
solutions that may appear to be acceptable if they are not
verified. Existing methods to verify GNSS solutions include
“dumping” the receiver, turning it upside down to cause the
RTK engines to reset, and re-observing the point at a later
time.
J-Field automates these processes with its built-in software
features of Verify and Validate. Verify automatically resets
the RTK engines after every fixed epoch is collected in
Phase-1 of its process. Epochs are placed into Groups or
buckets during Phase-1. Once a Group has met the required
Confidence Level and Minimum Phase-1 Duration (time
between the first and last epoch in that group), Phase-1 is
complete.
The Confidence Guard (CG) determines the size of the Group
or bucket. Each Group contains all the epochs located
within a specified radius (the CG value) from its center and
new Groups are created as necessary so that all epochs
fall into at least one Group. Each Group has its own Epoch
Counter, Confidence Level and Elapsed Time. A point may
fall into more than one group. The groups are sorted from
best to last by the sum of their Time and Confidence with the
current best group being shown within [ ] and others within
( ). Show on the Screen specifies how many groups will be
displayed on the plots on the screen. There is no limit to the
number of groups that will be stored internally but only up
to the best 6 will be displayed on the screen.
During Phase-2 the engines are not reset and solutions
which are located inside the CG of the selected Group are
added to that Group for the remaining number of epochs
that user has requested (Epoch Number, EN) in the How to
Stop screen. Epochs which are outside the CG of the selected
Group will be stored in a new (or previously created) group;
the RTK engines are reset if the epoch falls outside a sphere
with a radius twice that of the CG. If the number of epochs
falling outside of the current group reaches 30% of epochs
collected so far, the process will revert back to Phase-1 and
the Confidence Level of the current group will be reset to
0. Previously created groups will remain intact and once
an existing or previously created group meets the Phase-1
criteria, it will pass to Phase-2.
Validation is the final phase of the process. With this
feature enabled the RTK engines will reset one final time
at the end of the observation and collect 10 additional
epochs. Allowing sufficient time between Phase-1 and
the final Validation step will guarantee a bad solution is
not allowed to be accepted. From extensive testing in the
worst of multipath environments, a bad solution has yet
to be accepted when Verify and Validate are enabled with
a Minimum Duration of least 180 seconds. This will ensure
that at least two separate fixed initiations are acquired at
least 3 minutes apart.
Having at least 2 fixed initiations in
agreement and acquired at least 2 to 3 minutes apart has
been found to be the critical requirement to ensure that
bad fixed initiations are not accepted. In high multipath
environments the Boundary Action Profile should be used
to meet this requirement and guarantee a good initiation.
You must let entire collection process complete.
Confidence Level and Consistency Level are counters; the
Confidence Level of a group increments each time an epoch
with a new RTK initiation (Fix) is collected. It increments by
values of 1, 1.25, 1.5, 1.75, 2.0, or 2.5 for 1 to 6 fixed engines,
respectively. The Consistency Level of a group increments
with every epoch collected by values of 0, 0.1, 0.25, 0.5, 1.0,
and 1.5 for 1 to 6 fixed engines. The set Consistency Level
must be met before Phase-2 is allowed to end.
If high accuracy is needed in areas of high multipath and
areas with limited views of open sky (under full tree canopy
and urban canyon environments), longer observations
will improve accuracy. Repeated observation can also
be performed later (1 hour or more is recommended) to
improve accuracy. These repeated points can then be
averaged together with the Average function found in Cogo
Tools or with the Cluster Averaging function.
Recommended Collection Settings &
Default Action Profiles
Boundary Action Profile - To be used for control and
boundary shots and in high multipath environments (under
tree canopy, next to buildings, etc.)
Start with Start Button
Stop After: 100 epochs
Minimum Duration: 120 seconds (increasing this
to 180 is preferred in bad locations for additional
protection from accepting points with bad fixed
initiations and for better post-processing results)
Minimum Phase-1 Duration: 30 seconds
Verify with V6 Reset
Confidence Level: 10
Consistency Level: 10
Min RTK Engines: At least 2
Validate Result: with at least 2 engines
Correct for Tilts: Off (Rover pole must be plumbed)
Precise Topo - To be used for topographic shots where some
multipath may be present. The receiver should still have at
least a 50% clear view of the open sky.
Start with Start Button
Stop After: 10 epochs
Minimum Duration: 10 seconds
Verify with V6 Reset
Confidence Level: 5
Consistency Counter: 10
Min RTK Engines: At least 2
Validate Result: with at least 2 engines
Correct for Tilts: Off
Quick Topo - To be used for rapid topographic shots in open
sky environments. If it is difficult to obtain 5 engine fixed,
the environment may not be well suited for this profile and
the Precise Topo profile should be used.
Start with Start Button or Start When Tilted
Stop After: 2 epochs
Verify without V6 Reset
Consistency Level: 0
Min RTK Engines: At least 5