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Wndsn Quadrant Telemeter Tutorials

Making the most out of our graphical telemetry computers.

Like with many complex instruments, there are multiple ways to solve certain problems and to measure the required inputs. Combining the various functions leads to a multitude of advanced uses.


Determining Local Latitude

The local latitude corresponds to the angle between the horizon and the pole star.

Finding local latitude.

Finding local latitude.

To determine latitude (in the Northern hemisphere), we are sighting Polaris. The pole star, or Polaris, is useful because its angle to the horizon does not change with longitude or time. Also, Polaris is almost in line with the Earth's axis and hence can be used to determine North. From latitude 0° on the equator, Polaris is exactly on the horizon, i.e. it has an angle of elevation, or altitude of 0°. Conversely, from the North pole, the angle of elevation, or altitude is 90°. Therefore, the measured altitude of Polaris is equivalent to the local latitude.

Note that a measurement precision of e.g. 0.5° translates to 30' of latitude, or 30 nautical miles.

Example

  1. The latitude is the angle between the plumb line (which extends into the zenith) and the perpendicular to the sighting line; zero on the quadrant.
  2. Polaris, the sighted star, is measured at 30° from the horizon.
  3. The latitude at the location measured is thus 30°.

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