The tellurometer was the first successful

microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...

electronic distance measurement equipment. The name derives from the Latin ''tellus'', meaning Earth.

History

The original tellurometer, known as the Micro-Distancer MRA 1, was introduced in 1957. It was invented by

Trevor Wadley Trevor Lloyd Wadley, (1920 – 21 May 1981) was a South African electrical engineer, best known for his development of the Wadley Loop circuit for greater stability in communications receivers and the Tellurometer, a land surveying device. Lif ...

of the Telecommunications Research Laboratory of the

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

Council for Scientific and Industrial Research A council is a group of people who come together to consult, deliberate, or make decisions. A council may function as a legislature, especially at a town, city or county/shire level, but most legislative bodies at the state/provincial or nati ...

(CSIR). He was also responsible for the Wadley Loop receiver, which allowed precision tuning over wide bands, a task that had previously required switching out multiple

crystal oscillator A crystal oscillator is an electronic oscillator Electrical circuit, circuit that uses a piezoelectricity, piezoelectric crystal as a frequency selective surface, frequency-selective element. The oscillator frequency is often used to keep trac ...

Principle

The tellurometer emits a microwave-frequency

radio wave Radio waves (formerly called Hertzian waves) are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths g ...

. The remote station carries a

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight trans ...

that reradiates the incoming wave in a similar wave of more complex

modulation Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message ...

. The resulting

phase shift In physics and mathematics, the phase (symbol φ or ϕ) of a wave or other periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is expressed in such a s ...

is a measure of the two-way distance travelled. The results appear on a

cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a ...

with circular sweep.

Application

The tellurometer design yields high accuracy distance measurements over

geodetic Geodesy or geodetics is the science of measuring and representing the geometry, gravity, and spatial orientation of the Earth in temporally varying 3D. It is called planetary geodesy when studying other astronomical bodies, such as planets ...

distances, but it is also useful for second order survey work, especially in areas where the terrain is rough and/or the temperatures extreme. Examples of remote locations mapped using Tellurometer surveys are Adams Bluff,

Churchill Mountains The Churchill Mountains is a major range of mountains and associated elevations bordering the western side of the Ross Ice Shelf, between Byrd Glacier and Nimrod Glacier. They are south of the Britannia Range and north of the Geologists Range, ...

, Cook Mountains, Jacobsen Glacier, Mount Albright, Mount Predoehl, Mount Summerson, Sherwin Peak and Vogt Peak. The instrument penetrates haze and mist in daylight or darkness and has a normal range of 30–50 km but can extend up to 70 km. The MRB2 or Hydrodist was a marine version that was used in coastal

hydrographic survey Hydrographic survey is the science of measurement and description of features which affect maritime navigation, marine construction, dredging, offshore wind farms, offshore oil exploration and drilling and related activities. Surveys may als ...

s and calibrating ships using other survey navigation systems. They were used by the

Army of the Republic of Vietnam The Army of the Republic of Vietnam (ARVN; ; ) composed the ground forces of the Republic of Vietnam Military Forces, South Vietnamese military from its inception in 1955 to the Fall of Saigon on 30 April 1975. Its predecessor was the ground forc ...

in the late 1960s.

Commercial exploitation

Plessey The Plessey Company plc was a British electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after World War II by acquisition of companies and formed overseas compani ...

, the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

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

microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...

s for the product.

Gallery

File:Tellurometer somewhere cold and miserable cropped.jpg, Tellurometer being set up on a mountaintop in Alaska by the US Geodetic Survey File:Mountaintop tellurometer triangulation station Africa or Ethiopia 2.jpg, Tellurometer being set up by the US National Geodetic Survey in Ethiopia File:Mountaintop tellurometer triangulation station Africa or Ethiopia 1.jpg, Another tellurometer being set up in Ethiopia File:Tellurometer from National Geodetic Survey at Columbia Glacier.jpg, Another tellurometer from the US National Geodetic Survey at Columbia Glacier

References