Dr. GRAW Messgeräte, Germany
Atmospheric sonde GRAW M60
Atmospheric balloon soundings, 1945-1950
Royal Meteorological Institute
This type of radiosonde was developed between 1945 and 1950 by the company Dr. Graw Messgeräte in Berlin. It was used by the Royal Meteorological Institute of Belgium (RMI) and the Belgian Army for atmospheric temperature, pressure and air humidity soundings. The embedded sensors are a bimetal strip for measuring temperature, a hair hygrometer and a Vidie capsule for measuring pressure. The movement of the probe in the air during the ascent causes the eight-blade propeller to rotate; this is connected to a transmission tree, which is itself connected to a spiral that produces a rotation in the drum.
The drawing on the drum was designed so that two Morse characters are transmitted one after the other to send the measured data, depending on the groove.