Tellurometer

The Tellurometer was the first successful microwave electronic distance measurement equipment (EDM).

History
The original Tellurometer, known as the Micro-Distancer M/RA 1, was introduced in 1959. It was invented by Dr. Trevor Lloyd Wadley of the Telecommunications Research Laboratory of the South African Council for Scientific and Industrial Research (CSIR), also responsible for the Wadley Loop receiver, which allowed precision tuning over wide bands, a task that had previously required switching out multiple crystals.

Methodology
The Tellurometer emits an electronic wave: the remote station reradiates the incoming wave in a similar wave of more complex modulation, and the resulting phase shift was a measure of the distance travelled. The results appear on a cathode ray tube with circular sweep. This instrument penetrates haze and mist in daylight or darkness and has a normal range of 30-50 km but can extend up to 70km.

Application
The Tellurometer design yields high accuracy distance measurements over geodetic distances, but it is also useful for second order survey work, especially in areas where the terrain was rough and/or the temperatures extreme.

Examples of remote locations mapped using Tellurometer surveys are Adams Bluff, Churchill Mountains, Cook Mountains, Jacobsen Glacier, Mount Albright, Mount Predoehl, Mount Summerson, Sherwin Peak and Vogt Peak.

Accuracy
The models available included a 100km position fixing system which was able to measure up to 1km with an accuracy of 0.6mm.

Commercial exploitation
Plessey, the British electronics company, formed a new subsidiary known as Tellurometer (Pty) Limited in the 1960's to manufacture the product and to develop and sell derivatives. The Company subsequently introduced numerical displays, solid state transmitters, integrated circuits and eventually microprocessors for the product.