Projects:
Definition & Development
of Galileo
Signal Structure
Galileo
Test Bed GATE
ESA Galileo Test
Bed GSTB_V1
GNSS Software
Simulation
C-Nav
Study |
National Galileo Test Bed GATE
Predictability of User
Trajectories
For
some functions of GATE, it may be necessary to predict the position of a
moving vehicle into the near future. Predictions may be relevant for the
following cases:
-
Feedback of user position to solve the
near-far-problem. The current user position is fed back to
the control segment where it is used to steer the signal generators of
GATE’s space segment (adjustment of transmit power). Since it may take
some time for the control segment to receive, analyze and process the required
data, it may be useful to predict the path. This could be of importance
especially for fast vehicles (e.g. aircrafts).
-
Generation
of a navigation message for moving transmission
platforms.
In order to enable real-time operation, non-static transmission platforms
have to transmit their current position continuously in the form of a navigation
message. Again, it will take some time to process and broadcast the message.
Within that period of time, the sender and the user receiver (in case of
kinematic applications) have moved along their paths
The
following sample data has been analyzed:
-
Flight
data (recorded with GPS, RTK solution, WGS84 coordinates X,Y,Z)
-
Auto
car data (recorded with GPS,RTK solution, WGS84 coordinates
X,Y,Z)
To
analyze the flight and auto car data, a simple MATLAB graphical user interface
has been programmed. The tool is able to visualize the trajectory and to
extract any desired part of the path for further analysis. The prediction
of the trajectory can be done by means of two interpolation methods, namely
the polynomial fit and by use of cubic splines. MATLAB offers functions for
both approaches.
By means of this GUI, the user trajectory can
be extrapolated at any point in time by defining a specific amount of supporting
points, a specific amount of extrapolated points and a specific extrapolation
method. The program calculates the coordinate offsets dx,dy and dz with respect
to the actual trajectory and uses the spatial deviation
D=sqrt(dx²+dy²+dz²) for further analysis.
 GATE start page
Positioning of pseudolites
Tropospheric path delay
Predictability of user trajectories |
