equipment was obviously intended to meet the need for a mobile and quickly
to assemble unit. The parts of the equipment were transported on a two wheeled
trailer, to be drawn by a motor vehicle to the observation location, where
it was built up on the trailer in a very short time. The light and compact
assembly formed a striking contrast with the heavy foreign equipments.
Additionally the manufacturing costs were considerably less. Supplementary to these equipments field glasses and transmission systems were delivered. This system comprised the electrical transport of the chart angle and elevation from the listening equipment to the field glasses and from the field glasses to a search light.
The delivery of this equipment to the Netherlands East Indies defence in 1936 amounted to six complete installations.
It had become evident in the thirties that the acoustic determination of direction could no longer cope with the increasing speed of airplanes due to the low speed of sound. The discovery in the Measurements Building of radio reflection by airplanes was therefore applied to remove this limitation. The result was the then called "electric" listening equipment (later called Radar) of which the first preproduction models were ready in the first months of 1940.