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Once the displayed humidity equals the calibrated source, press and hold the ADJUST 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 affect 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:

http://ambientweather.wikispaces.com/ws07

5.6.2 Temperature Calibration

Prior to entering the calibration mode, press the CHANNEL/+ button to select the temperature you

wish to adjust.

To enter the temperature calibration mode, press and hold the ADJUST button for 5 seconds and the

temperature value will begin flashing. Press the CHANNEL/+ button to increase the temperature and

the MIN/MAX/- button to decrease the temperature reading in 0.1° increments. To rapidly increase

(or decrease) the temperature reading, press and hold the CHANNEL/+ or MIN/MAX/- button.

To return the temperature to the actual or uncalibrated measurement, press the ADJUST button.

Once the displayed temperature equals the calibrated source, press and hold the ADJUST button for

three seconds, or wait 15 seconds for timeout, and the temperature value will stop flashing.

Discussion: Temperature errors can occur when a sensor is placed too close to a heat source (such

as a building structure, the ground or trees).

To calibrate temperature, we recommend a mercury or red spirit (fluid) thermometer. Bi-metal (dial)

and other digital thermometers are not a good source and have their own margin of error. Using a local

weather station in your area is also a poor source due to changes in location, timing (airport weather

stations are only updated once per hour) and possible calibration errors (many official weather stations

are not properly installed and calibrated).

Place the sensor in a shaded, controlled environment next to the fluid thermometer, and allow the

sensor to stabilize for 48 hours. Compare this temperature to the fluid thermometer and adjust the

console to match the fluid thermometer.

Ambient Weather WS-07 User Manual

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