Main Office
Via Zago, 2
BOLOGNA
ITALY - 40128

Laboratories
Via Gobetti 52,
BOLOGNA
ITALY - 40128

 
     

PLUDIX is made of a two main parts; the sensor is located in a waterproof Fiberglass container to be placed outside, and is connected by a cable to the power supply/signal processing unit.

 

The sensor

The sensor is an X band continuous wave, low power (10 mW) Doppler Radar (9.5 GHz frequency of operation). The radar electronics are hosted in a custom made microwave module tuned to the proper sensitivity to detect the weakest precipitation. The upper part of the container (dome) is shaped in order to minimize dry deposition and snowcover, and can be heated.

The length of the cable connecting the sensor with the power supply/signal processing unit can be extended to several tens of meters.

 

The signal processing unit

The signal processing unit receives, elaborates and stores the signal coming from the sensor. The signal processing unit can communicate to the user in three different ways: serial port RS232C, ethernet and modem.

 

Functioning principle

The MW beam emitted by an upward oriented antenna is backscattered by hydrometeors in free fall. Near the ground each hydrometeor has reached an aerodynamic equilibrium and falls at a constant terminal velocity only as a function of its size. The backscattered signal at the receiving antenna is comprised of many components that are shifted in frequency from the transmitted signal depending on the hydrometeors' terminal velocities (Doppler effect). The amplitude of these components is a function of the reflectivity of the hydrometeors and their concentrations in the volume seen by the sensor.

Since a given drop at terminal velocity is not generating a constant but rather a variable doppler echo depending on its position in space, a special algorithm has been developed which obtains the hydrometeor size distribution from the signal spectrum and hence the parameters characterizing the precipitation.