Satellite Visibility / Elevation Mask Calculator
Estimate the elevation angle blocked by an obstacle and recommend the GNSS cutoff angle for your site.
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About satellite visibility and elevation masks
GNSS receivers use satellites above a minimum elevation angle called the "cutoff" or "elevation mask". Low-elevation satellites provide weaker signals (longer atmospheric path), higher multipath risk, and more ionospheric delay. Typical cutoff is 10° for open sites, 15° for moderate obstructions, and 20°+ for urban areas.
This calculator translates a physical obstacle (a building, tree line, or terrain) into an elevation angle from the receiver. If a 10-meter building is 20 meters away, it blocks everything below 26.57°, so satellites below that angle are lost.
Elevation mask formula
This is a simplified two-dimensional formula. For complete site analysis use a panoramic photograph with an azimuth-based skyplot, which shows exactly which sectors of the sky are obstructed.
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- sat_visibility.factor_7
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- sat_visibility.dop_1 \u2014
- sat_visibility.dop_2 \u2014
- sat_visibility.dop_3 \u2014
- sat_visibility.dop_4 \u2014
- sat_visibility.dop_5 \u2014
Practical use cases
Pre-survey site reconnaissance: before setting up a base station, check whether obstructions will limit satellite visibility below acceptable thresholds.
Urban surveys: map buildings around your planned observation points to predict the worst-case elevation mask.
Continuous reference stations: an elevation mask over 20° in any azimuth direction can bias solutions long-term.
Mission planning: combined with satellite orbit predictions, elevation masks determine whether enough satellites will be visible at your preferred observation time.
Frequently asked questions
What is a good cutoff elevation angle?
10° is standard for open-sky conditions. Raise to 15° if multipath is a concern, but do not go above 15° unless necessary because it reduces satellite count.
Why not set the cutoff high to avoid multipath?
Higher cutoffs lose more satellites, degrading DOP and positioning accuracy. 10-15° is the optimal compromise for most applications.
How do trees affect GNSS signals?
Leaves attenuate GNSS signals by 2-20 dB depending on species and density. A line of mature trees at 10-meter height and 20-meter distance creates an effective 26° mask for all azimuths they cover.
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Related topics
See our glossary entries for multipath, PDOP, and cutoff elevation angle.