Version 1.3
©Copyright 2013, Ambient LLC. All Rights Reserved.
Page 21
5.5.2
Calibration Procedure
To enter the calibration mode from the normal mode, press and hold the
HISTORY
button for eight
seconds. The backlight turns on and the console beeps. The first calibration factor will being
flashing. To exit the calibration mode, press the
HISTORY
button again.
The following section outlines setting the calibration values.
The calibration mode can be exited at any time by either pressing the
HISTORY
button or waiting for
the 30-second time-out to take effect. You can skip over any setting by pressing the
SET
button
again.
Holding the
+
button or
MIN/MAX
button for two seconds will change the calibration values rapidly.
1.
Wind Speed (Gust) Calibration
. After entering the Calibration Mode, the Wind Speed
Calibration value will begin flashing (the default is 1.0). Press the
+
button or
MIN/MAX
button to adjust the wind speed calibration factor from -0.75 to 1.25, where:
Calibrated Wind Speed = Calibration factor x Measured Wind Speed
Note:
The wind gust is also affected by the wind speed calibration factor.
Discussion
: Wind speed and wind gust are adversely affected by installation constraints.
The rule of thumb is to install the weather station four times the distance of the height of the
tallest obstruction (for example, a 20’ house would require an installation 80’ away).
In many instances, due to trees and other obstructions, this is not possible. The wind speed
calibration allows you to correct for these obstructions.
In addition to installation challenges, wind speed bearings (any moving part) wears over time.
To correct for wear, the correction value can be increased until the wind cups must be
replaced.
Without a calibrated source, wind speed is a difficult parameter to measure. We recommend
using a calibrated wind meter and constant, high speed fan.
2.
Rainfall Calibration (1 Hour, 24 Hour, Daily, Monthly, Total)
. Press the
SET
button again
and the Rain Calibration value will begin flashing (the default is 1.0). Press the
+
button or
MIN/MAX
button to adjust the rain calibration factor from -0.75 to 1.25, where:
Calibrated Rain = Calibration factor x Measured Rain
Discussion
: The rain collector is calibrated at the factory based on the funnel diameter.
The bucket tips every 0.01” of rain (referred to as resolution). The accumulated rainfall can
be compared to a sight glass rain gauge with an aperture of at least 4”. The following is a link
to an accurate sight glass rain gauge:
http://www.ambientweather.com/stprraga.html
Note that debris and insects can collect inside the tipping mechanism (they make a good
spiders nest). Carefully remove the funnel and inspect the tipping mechanism for debris prior
