ZED-F9K - Integration manual
B Reference frames
Real time kinematic (RTK) is a differential system where the rover uses the corrections from a
reference station or a reference station network. The rover receiver will calculate its position in the
reference frame used by the service provider in its correction stream. If the output is required in a
different reference frame, then a (custom) datum transformation is required.
For example, if an application requires the position in the ITRF14 reference frame but the correction
service is using the ETRF14 reference frame - to which the RTK solution will also be referring - then
this reference frame offset needs to be compensated. For example if utilizing a truth system which
is using corrections referring to different reference frame, it is important to compensate for the
reference frame offset to avoid systematic errors in the analysis.
Terrestrial reference system is a coordinate reference system which is rotating in space with the
rotation of the Earth. The reference system is an abstract concept that is realized by obtaining
coordinates for some points on the surface of the Earth. This kind of realization is called a reference
frame. For more details, see for example
. Commonly used reference systems include
Internation Terrestrial Reference System (ITRS) and European Terrestrial Reference System 1989
(ETRS89).
Widely used reference frames include for example International Terrestrial Reference Frame (ITRF)
and European Terrestrial Reference Frame (ETRF). ITRF is a realization of ITRS, done every few years.
Latest realizations of ITRF are ITRF2008 and ITRF2014. ETRF is a realization of ETRS89, done every
few years. Latest realizations are ITRF2005 and ETRF2014.
For example, the EUREF is used to realize the ETRS89. For information, see their homepage:
See the ITRF website for more information and an online transform calculator:
.
Another online tool for transformations is available on the EUREF network page:
Reference frames can have constant offsets between each other but, in addition to that, they can
also drift and rotate with respect to each other. One major reason for this is that the tectonic plates
move constantly and the reference frames that are attached to the tectonic plates move along with
the plates.
The ZED-F9K stores the EGM96 geoid model with limited resolution, leading to degraded
precision of the reported mean sea level height and geoid separation. If the user application
needs higher geoid separation accuracy, it is required to apply its own adjustment to the
ellipsoidal height output from the ZED-F9K.
C RTK configuration procedures with u-center
This section provides some guidance for using u-center to evaluate ZED-F9K RTK operation.
C.1 Receiver configuration with u-center
In this example, UART1 is configured to use a suitable baud rate for communicating with a host
PC running u-center. A set of output messages are enabled so that the receiver status can be
monitored.
Using the UBX-CFG-VALSET configuration window, set the UART1 interface for the correct host
baud rate:
UBX-20046189 - R01
Appendix
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C1-Public
Early production information
