Line of Sight / Viewshed Tool

Summary: Estimating radio reception from a chosen location, and grading which known transmitter sites you should be able to hear.

The Viewshed Tool calculates estimated radio line-of-sight coverage from a point you choose — either your current location or a pin you drop on the map — taking terrain elevation, Earth curvature, and radio refraction into account.

To run a viewshed:

1. Open the Viewshed Tool.
2. Choose your reference point — your location, or drop a pin.
3. Choose a mode:
   • Ground — pick an antenna height preset: Handheld (2.5m), Bungalow (8m), House (12m), or Mast (25m).
   • Inflight — models coverage against aircraft altitude instead of a fixed antenna height.
4. Run the calculation.

The result is a green/yellow/red coverage overlay on the map, with a legend explaining what each colour means in terms of expected signal reception.

“What Can I Hear?”

From the same panel, use What Can I Hear? to automatically grade every known transmitter site (see Transmitter Sites and Amateur Repeaters) against your chosen location — telling you which ones you should realistically be able to receive, rather than checking each one manually.