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For the complete documentation index, see llms.txt.
Every ground station sits inside a real landscape. Hills, masts, buildings, and the curve of the terrain block the sky unevenly — a station might see a spacecraft just a couple of degrees above the horizon to the north, and not until well into double digits to the south-east. An elevation mask is how you tell VALAR the actual shape of that skyline: the lowest elevation angle your station can use at each compass bearing, surveyed once and uploaded as a file. This is different from a station’s minimum elevation, which is a single policy floor — a link-budget or regulatory limit you’d apply the same way in every direction, regardless of what is actually on the horizon.

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Why the Shape of the Horizon Matters

A minimum elevation alone assumes a station has the same clear view in every direction. Real sites rarely do. If a ridge to the south blocks everything below 12 degrees but your station’s minimum elevation is set to 5 degrees, a flat-minimum calculation reports contacts your antenna physically cannot make — the spacecraft is above the configured floor and behind the ridge at the same time. An elevation mask corrects this. Once your station has a surveyed horizon on file, passes are computed against the shape you actually have, not an idealized flat one. If this means a station reports fewer passes than it used to, that is the correction working as intended, not a loss of capability — those passes were never really there; the platform was simply not accounting for the terrain that always blocked them.

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How the Mask and the Minimum Elevation Combine

A station’s elevation mask and its minimum elevation are not alternatives where one silently wins. They combine at every compass bearing by taking whichever is higher. This combined value is the station’s applied horizon — the actual threshold pass computation checks a spacecraft’s elevation against. Two things follow from this, and both are deliberate:
  • Your elevation mask can never open up access below your configured minimum elevation. If you intend a low surveyed value to take effect exactly as surveyed, your minimum elevation needs to be set at or below it.
  • Your minimum elevation can never paper over terrain your survey shows is blocking the sky. A ridge your survey says sits at 15 degrees stays at 15 degrees in the applied horizon, even if your minimum elevation is set to 0.
The applied horizon is what every chart, preview, and pass computation on the platform uses — never a value recalculated independently by a different screen. See Ground Stations for where to view a station’s applied horizon and how to upload a survey.

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What Happens When a Pass Disappears

If a pass you were used to seeing no longer appears after you upload a survey, that is expected: your station’s real horizon — not the flat minimum elevation it used before — now governs that window, and the spacecraft never actually cleared your antenna’s real sightline there. If instead a station reports no results at all where you expected some, check the per-station outcomes on the Timeline — that is a different situation from a single blocked pass, and the timeline tells you which one it is.
  • Passes Overview — how the Passes area’s pages fit together.
  • Ground Stations — upload an elevation mask and view a station’s applied horizon.
  • Timeline — what each station’s outcome on the timeline means.