In 2015 I was contacted by a former teacher of the Internationale Agrarische Hogeschool (International Agricultural University) Larenstein as he had two Geodimeter total stations that were about to end up in the skip.

According to the manufacturer "The Geodimeter System 400 is the first surveying system where hardware and software have been integrated in an intelligent and powerful unit."¹ The Geodimeter System 400 was launched in 1986 as a modular system. Several models were launched in three groups: the 'conventional' total station, the alphanumerical total station, and the servo operated 'surveying computer'. The two Geodimeters shown here are a conventional one (the 420) and an alphanumerical one (the 424).

Before the Geodimeter System 400, total stations like the Kern E1 could already measure vertical and horizontal angles, and distances, but at the most they were only able to reduce slope distances to vertical and horizontal distances. The Geodimeter System 400 had onboard software for traversing with "... automatic corrections for any plumb error, collimation error and trunnion axis tilt..." allowing to "... measure angles in one face only with full accuracy...", while one could "...also make two face angle measurements with automatic arithmetic mean value."²

In addition to that it had onboard software to assist in setting out, where one could choose between angular or positional differences. It had the advantage of an electronic dual axis vial which allowed to level the instrument without having to turn it 90 degrees several times. Another advantage was data transmission via telemetry, making it possible to use it as a positioning system like the 1992 Krupp Atlas PolarTrack, albeit without automatic tracking.²

The specifications of the two Geodimeter System 400 shown here do not differ much. The conventional one is a model 420 with a distance measuring accuracy of 5mm+3ppm and an angular accuracy of 0.6mgon (2").³ The alphanumerical one is a model 424 with a distance measuring accuracy of 3mm+3ppm and an angular accuracy of 0.6mgon (2").⁴ The main difference is thus that the conventional one cannot enter alphanumerical characters using the keyboard.

Although more accurate than the Wild TC1 and Kern E1, the Geodimeter 420 and 424 were not the most accurate total stations Geotronics produced. With 2mm+3ppm distance accuracy and 0.3mgon angular accuracy their model 444 was roughly twice as accurate.⁵

When they were launched the models 420 and 424 were not only more accurate, but with a price of around fl.40,000.- also cheaper than the Wild TC1 and Kern E1. The above mentioned model 444 would have cost roughly the same as the Wild TC1.

Both instruments came with their original cases, spare batteries, a charger and prism target. As is not unusual with electronic instruments both instruments are no longer operational and are thus relics of times past.

[1]: Geotronics AB, Geodimeter System 400: Advanced Field Intelligence, (Danderyd, 1986), p.1.

[2]: Geotronics AB, Geodimeter System 400: Advanced Field Intelligence, (Danderyd, 1986), p.2. Geotronics AB, Hydrographic positioning: A System Presentation from Geotronics AB, (Danderyd, 1987), pp.5-6.

[3]: Geotronics AB, Geodimeter System 400: Geodimeter 420LR, (Oberursel, 1988), p.2.

[4]: Geotronics AB, Geodimeter System 400: Technische Spezifikationen, (Oberursel, 1988), p.6.

[5]: Geotronics AB, Geodimeter System 400: Technische Spezifikationen, (Oberursel, 1988), p.7.