How are the individual parameters of the WXT510 calibrated?

1. Rain
The calibration is based on generation of elastic waves into the RAINCAP^® Sensor plate due to thermal expansion by pulsed laser irradiation. The generated output voltage signal of the RAINCAP^® Sensor is measured and compared to reference values in order to calculate calibration coefficients. The optical pulse energy is measured with a NIST -traceable laser energy meter. Learn more about the RAINCAP^® Sensor.
 
2. Wind
The WINDCAP^® sensor measures the time required for sonic impulses to move from one transducer to the other. The only two parameters that affect the sensor's accuracy are time and distance. The distance is the physical separation between transducers. The time-of-flight for a sonic impulse to travel between transducers is measured and stored during factory calibration procedure. Reverse validation of distance can be done in a zero-wind chamber. Learn more about Vaisala Ultrasonic Wind Measurement Technology.

3. PTU Module
The barometric pressure, temperature and relative humidity module is calibrated conventionally by comparison to appropriate standards which are traceable to various standards organizations. More information on calibration traceability.