This innovation makes it possible to get automatic observations of the Cloud Cover Factor, CCF 24 hours a day. It consists of a daytime unit that observes the sky in 4 directions in parts of the solar spectrum, a nighttime unit that observes the sky in the thermal infrared spectrum, and a microcomputer for evaluating the signals. The bearing principle at nighttime is not the same as that during daytime.
At nighttime, the difference between the incoming and outgoing thermal infrared radiation is measured using a type of bolometer.
In the daytime, the sky is observed using 4 silicon photodetectors in different parts of the sky. The exact concept is still our secret but we can say that the calculations for calculating the cloud cover factor are made in a microcomputer.
The microcomputer also calculates when the output is taken from the night ( infrared ) information or from the daytime ( shortwave ) information.
The unit should be mounted horizontally at a location with a reasonably free horizon ( no object more than ten degrees above the horizon, or so ). In the lower part of the box (outside the sealing gasket) there are four channels, for M6 screws, on a rectangle 82 * 204 mm that can be used for the mounting.
The grey line above is the output from a PCCD sensor
Passive Cloud Cover Detector, PCCD