Placing PWD - AWS810

AWS810 Installation Guide

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User guide

Place the present weather detector in a suitable site to ensure representative ambient measurements.


Avoid obstacles in the line-of-sight of the transmitter and receiver units.

  • Minimum clearance of 100 m (328 ft) from all large buildings and other structures that generate heat and obstruct precipitation droplets.
  • Avoid the shade of trees because the trees may cause changes in the microclimate.

Reflective surfaces

Make sure that the site is free of reflective surfaces disturbing the optical measurement.

  • If obstacles reflect the transmitter beam back to the receiver unit, the sensor indicates too low MOR values because the reflected signal cannot be distinguished from the scatter signal.
  • Rotate the sensor cross arm and check the visibility readings.

    If there are reflections, the corresponding visibility reading changes depending on the cross arm orientation.

  • On the roadside:

    • Do not aim the receiver against the traffic flow. Possible reflections from the passing cars can generate false snow detections in the winter.
    • Ensure that the rising or setting sun does not cause reflections from the road surface to the receiver.


Make sure that the site is free of obvious sources of contamination, especially when placing the sensor next to a road.

  • Face the transmitter and receiver away from contamination sources, such as spray from passing vehicles.
  • Dirty lenses cause the sensor to report too high visibility values.
  • The sensor automatically detects excessive contamination.

Bright lights

Do not point the receiver or transmitter toward powerful light sources. The receiver circuit may become saturated in bright light, in which case the built-in diagnostics indicate a warning.

  • Bright daylight increases the noise level in the receiver. Vaisala recommends pointing the receiver North in the Northern Hemisphere, and South in the Southern Hemisphere.
  • Park stationary maintenance vehicles with flashing lights outside the sensor's measurement area.

Powering and heating

Make sure power supply and communication lines are available, as this influences the amount of work and accessories needed, and installation cost.

For very harsh winter conditions, use the optional hood heaters to prevent ice and snow accumulation.