User manual

A further difficulty is that most hygrometers sense relative humidity rather than the absolute amount

of water present, but relative humidity is a function of both temperature and absolute moisture content,

so small temperature variations within the air in a test chamber will translate into relative humidity

variations.

All hygrometers are preset at the factory but may require recalibration due to shipping and storage or

electronic drift. There are several ways to calibrate the humidity sensors, including sling

psychrometers (which compare wet and dry bulb temperatures to measure relative humidity), or salt

calibration kits, available at AmbientWeather.com. Different salts, when mixed with water to create

a sludge or slurry, will generate a consistent and predictable humidity.

Comparing the humidity to an unknown source or an official weather station in your area is not a valid

calibration methodology.

5. Glossary of Terms

Term Definition

Accuracy Accuracy is defined as the ability of a measurement to match the actual

value of the quantity being measured.

Calibration The act of checking or adjusting (by comparison with a standard) the

accuracy of a measuring instrument.

Hygrometer A hygrometer is a device that measures relative humidity. Relative

humidity is a term used to describe the amount or percentage of water

vapor that exists in air.

Range Range is defined as the amount or extent a value can be measured.

6. Specifications

6.1 Wireless Specifications

• Line of sight wireless transmission (in open air): 300 feet. 100 feet under most conditions.

• Frequency: 433 MHz

• Update Rate: 48 seconds

6.2 Measurement Specifications

The following table provides specifications for the measured parameters.

Measurement Range Accuracy Resolution

Indoor Temperature 32 to 140 °F ± 2 °F 0.1 °F

Outdoor Temperature -40 to 149 °F ± 2 °F 0.1 °F

Outdoor Humidity 1 to 99% ± 5% (accuracy is only

guaranteed between 20

to 95%).

1 %

6.3 Power Consumption

• Base station : 2 x AA 1.5V Alkaline batteries

• Remote sensor : 2 x AAA 1.5V Alkaline batteries

• Battery life: Minimum 24 months for base station