Vaisala FD12P - Manual (Page 101)

Chapter 5 _______________________________________________________ Functional Description
VAISALA _______________________________________________________________________ 101
Figure 25 DRD12 Block Diagram
The DRD12 sensing surfaces are heated by heating elements built into
the surfaces. The heating power varies automatically (by built-in
temperature control), but it can be switched off with a digital control
signal. When the heating is off, the surfaces become extremely
sensitive to all moisture in the air.
DTS14B Temperature Sensor
The DTS14B is a PT100 temperature sensor with a special mechanical
construction. The temperature is measured once a minute using the
DRI21 temperature channel.
The DTS14B is attached to the sidewall of the mast to achieve direct
thermal contact with the mast surface. The temperature (TS) is used to
select the default precipitation type and to separate freezing rain from
non-freezing rain.
FDP12 Control Unit
The FDP12 Control Unit consists of the microprocessor,
communication interface, memory, frequency measurement circuitry,
watchdog, monitoring circuitry, and digital-to-analog converter.