| CPC G01S 19/08 (2013.01) [H04L 67/12 (2013.01); G08G 1/0968 (2013.01)] | 20 Claims |
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1. A method of determining visible GNSS satellite positions in a satellite orbit by a ray-based model, the method comprising:
possessing an orbital segment representing the transit of a satellite in orbit over time;
possessing a coarse ray angle interval;
possessing a fine ray angle interval;
possessing a Digital Surface Model (DSM);
performing a first pass, for each coarse ray angle interval in the orbital segment, by:
propagating a coarse ray between a Valid Observable Point (VOP) and points on the orbital segment at a respective coarse ray angle to determine whether the coarse ray is obstructed by features of the DSM, and
recording a status of the coarse ray with LOS visibility or NLOS visibility based on whether the coarse ray was obstructed;
for each pair of successive coarse rays in the first pass,
if the successive coarse rays have different status,
then designating the coarse ray with NLOS visibility; and
performing a second pass, by:
propagating, with respect to each designated coarse ray, fine rays between the VOP and points on the orbital segment at fine ray angle intervals, and
saving results from the second pass, including an indication of a time at which the LOS to the satellite becomes obstructed.
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