Campbell Scientific WXT520 Weather Transmitter - Manual (Page 7)

WXT520 Weather Transmitter
1. Introduction
The WXT520 Weather Transmitter, manufactured by Vaisala, measures wind
speed and direction, precipitation, barometric pressure, temperature, and
relative humidity—all in a single device that has no moving parts. The
WXT520’s SDI-12 signal can be measured by any of our SDI-12 equipped
dataloggers. The WXT520 is about the size of our larger Gill radiation shield,
making it ideal for use with our CR200(X)-series dataloggers in applications
requiring quick, short-term deployment. However, the WXT520 is not
intended for weather stations that require research-grade performance.
Before installing the sensor, please study
• Section 2, Cautionary Statements
• Section 3, Initial Inspection
2. Cautionary Statements
• Although the WXT20 is rugged, it should be handled as precision
scientific instrument.
3. Initial Inspection
• Upon receipt of the WXT20, inspect the packaging and contents for
damage. File damage claims with the shipping company.
4. Overview
4.1 Wind Speed and Direction
The WXT520's wind sensor consists of three equally spaced transducers that
produce ultrasonic signals. Wind speed and direction are determined by
measuring the time it takes for the ultrasonic signal of one transducer to travel
to the other transducers. Wind direction is not calculated when the wind speed
drops below 0.05 m/s. In this case, the last calculated direction output remains
until wind speed increases. The computed wind speeds are independent of
altitude, temperature, and humidity. The WXT520 is preconfigured to provide
the minimum, average, and maximum values for both wind speed and
direction. Default wind speed units are m/s.
4.2 Precipitation
The WXT520 uses the RAINCAP® Sensor to measure accumulated rainfall,
rain intensity, and rain duration. Precipitation is measured one raindrop at a
time. Whenever a raindrop hits the precipitation sensor, an electrical signal is
produced that is proportional to the volume of the drop.
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