The design is inspired by professional cup anemometers, but with two cups instead of three, to make the device pocket friendly and super rugged.
The Mjolnir wind meter uses the magnetic field sensor in the phone, so the device contains no eletronics.
The design of the Vaavud Sleipnir wind meter is inspired partly by professional cup anemometers, and partly by a Danish developed wind turbine with vertical blades. The carefully designed, asymmetrical rotor accelerates slightly when the largest surface is hit by the wind.
The built-in sensor makes 40.000 measurements per second allowing the app to detect even the slightest variations in wind speed. This high frequency signal can be used to derive both wind speed and direction.