... a study in kinematic GNSS

S-plan

This java applet was developed in 2000 during my master thesis project about GPS for Road Pricing.

The applet uses various input parameters to describe a user environment and then calculates standard deviations on the pseudorange and HDOP values. The results are presented in a percentage interval. The calculations are based on a 28 SV GPS constellation and a 28 SV Galileo constellation.


Position of the car in geographic coordinates

The position shall be inputted in degrees, minutes and seconds in WGS84.
The inputted height is the ellipsiodal height and not the orthometric height.


The user environment: (see figure)

The azimuth angle:(Azv) This parameter state in which angle postive from true north, that the road is heading.
Breadth of the road:(b) This parameter state the breadth of the road from the front of the left building to the front of the right building.
Front height:(F) This parameter state the height of the front of the left and the right buildings.
Distance to the right of the central line:(M) This parameter state the distance to the right of the center line that the car is positioned.
The user environment

Elevationsask: This parameter state the angle (from horizon and up), where satellites above will be considered visible and satellites below will be considered invisible.
Galileo-simulation: The simulated Galileo constellation is extended with the GPS constellation. Please be aware that the Galileo constellation is based on knowledge from 2000, where the orbits from Galileo was not determined yet.
Interval between satellitpositions: This parameter state the interval between the satellite positioning update. Are you working on a slow computer, 30 minutes update is recommended. The most precise results will be with 5 minute update.

Output

The calculated values are stated in percentages.
3 * standard deviation: This output state the horizontal standard deviation with a 99.7 % significance.
Satellitees: This output state the number of visible satellites.

Impossible to determine a position: This outut state in how many percent of the time where the number of visible satellites will be 2 or less. This means in situations where it is impossible to determine a position based on the GPS/GNSS signals alone.

If the program for some reasons fail to work, please try the following, before mailing me:
Control that the numbers are written as integers.
Control, that the distance to the right of the central line is not bigger than the half breadth of the road.


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