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Copyright © 2015 Coda Octopus Products Ltd
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F180R MOTION Sensor User and Reference Guide
NOTE: The Position and Velocity accuracies are not inputs to the function that
determines the calibration state but you should expect these to be within
specification once the system is calibrated.
Innovations
The Innovations area displays the innovations for several F180R System parameters.
Innovations are the difference between the INS predicted values for position, speed, attitude
and heading, and the latest values obtained from GNSS data. In general, innovations should be
in the green or orange areas of the display; innovations that remain in the red area for an
extended period may indicate a problem.
Typical causes of higher than expected innovations are:
F180R System unit and GNSS antennas moving independently of each other. Ensure that
the Antennas are securely mounted to the vessel, and that the mounting point is not
itself flexing and moving relative to the vessel hull; check that the F180R System unit is
firmly secured to a structural area of deck (not a hatchway or other moveable structure).
If the F180R System unit is a long way from the antennas, hull flexing may cause higher
than expected innovations to occur.
Poor or interrupted GNSS coverage. Check that the GNSS antennas are located as high as
possible on the vessel, and have an uninterrupted view of the sky. Surveying under
trees, bridges, or other structures which obscure the GNSS antennas' view may cause
higher than expected innovations
There is a coloured bar graph for each variable and can be one of three colours:
Red – innovation is significantly above the level that one would expect
Orange – innovation is above, but within 20%, of the maximum level than one would
expect
Green – innovation is at or better than the level that one would expect
Innovations do not directly affect the calibrated state of the F180R System.
5.5.2 Heading Initialisation
When the F180R System is powered on or restarted it needs to carry out a heading
initialisation process, which allows the system to determine the orientation of the GPS
antenna baseline so that the system can acquire accurate heading data.
The heading initialisation dialog reports the system status with respect to the progress of the
carrier-phase measurement to resolve the integer ambiguity variable. This measurement is a
satellite-to-receiver range measurement that results in an improved GPS accuracy over the
more basic pseudorange measurement.
By defining a fixed Antenna Separation value, you help the F180R System define a constrained
search space model, which allows determination of the required integer ambiguity in a
relatively short time scale. As a result of this measurement, the F180R System is fully
initialised and is then ready to start outputting position, heading and attitude data.
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