Vaisala WXT510 - Manual (Page 26)

User’s Guide ______________________________________________________________________
24 __________________________________________________________________ M210470EN-D
- Time mode:
Transmitter sends automatically a precipitation message in the
update intervals defined by the user.
- Polled mode:
Transmitter sends a precipitation message whenever requested by
the user.
More information about the precipitation sensor operation modes can be
found in section
Precipitation Sensor on page 103 .
PTU Measurement Principle
The PTU module contains separate sensors for pressure, temperature,
and humidity measurement.
The measurement principle of the pressure, temperature, and humidity
sensors is based on an advanced RC oscillator and two reference
capacitors against which the capacitance of the sensors is continuously
measured. The microprocessor of the transmitter performs
compensation for the temperature dependency of the pressure and
humidity sensors.
The PTU module includes
- capacitive silicon BAROCAP
®
sensor for pressure measurement,
- capacitive ceramic THERMOCAP
®
sensor for air temperature
measurement, and
- capacitive thin film polymer HUMICAP
®
180 sensor for humidity
measurement.
Heating (Optional)
Heating elements located below the precipitation sensor and inside the
wind transducers keeps the precipitation and wind sensors clean from
snow and ice. A heating temperature sensor (Th) underneath the
precipitation sensor controls the heating.