Version 1.0
©Copyright 2017, Ambient LLC. All Rights Reserved.
Page 10
5.8 Adjustment or Calibration
Note:
The calibrated value can only be adjusted on the console. The remote sensor(s) always
displays the un-calibrated or measured value.
Note:
The measured humidity range is between 10 and 99%. Humidity cannot be accurately
measured outside of this range. Thus, the humidity cannot be calibrated below 10% or above 99%.
The purpose of calibration is to fine tune or correct for any sensor error associated with the devices
margin of error. The measurement can be adjusted from the console to calibrate to a known source.
Calibration is only useful if you have a known calibrated source you can compare it against, and is
optional. This section discusses practices, procedures and sources for sensor calibration to reduce
manufacturing and degradation errors. Do not compare your readings obtained from sources such as
the internet, radio, television or newspapers. They are in a different location and typically update once
per hour.
The purpose of your weather station is to measure conditions of your surroundings, which vary
significantly from location to location.
5.8.1
Humidity Calibration
Prior to entering the calibration mode, press the
CH/+
button to select the humidity sensor you wish to
adjust.
To enter the humidity calibration mode, press and hold the
SET
and
MIN/MAX
buttons at the same
time for 5 seconds and the humidity value will begin flashing. Press the
CH/+
button to increase the
humidity and the
MIN/MAX/-
button to decrease the humidity reading in 1% increments. To rapidly
increase (or decrease) the humidity reading, press and hold the
CH/+
or
MIN/MAX/-
button.
To return the humidity to the actual or uncalibrated measurement, press the
SET
button.
will be displayed when the humidity calibrated measurement.
Once the displayed humidity equals the calibrated source, press and hold the
SET
button for three
seconds, or wait 15 seconds for timeout, and the humidity value will stop flashing.
Discussion
: Humidity is a difficult parameter to measure electronically and drifts over time due to
contamination. In addition, location has an adverse effect on humidity readings (installation over dirt
vs. lawn for example).
Official stations recalibrate or replace humidity sensors on a yearly basis. Due to manufacturing
tolerances, the humidity is accurate to ± 5%. To improve this accuracy, the indoor and outdoor
humidity can be calibrated using an accurate source, such as a sling psychrometer:
http://www.ambientweather.com/mafaredspslp.html
or one step humidpak calibration kits (reference Section 9). You can also use common table salt,
water and a plastic bag:
