The tellurometer was the first successful

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...

electronic distance measurement Length measurement, distance measurement, or range measurement (ranging) refers to the many ways in which length, distance, or range can be measured. The most commonly used approaches are the rulers, followed by transit-time methods and the i ...

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. ...

of the Telecommunications Research Laboratory of the

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

Council for Scientific and Industrial Research The Council for Scientific and Industrial Research (CSIR) is South Africa's central and premier scientific research and development organisation. It was established by an act of parliament in 1945 and is situated on its own campus in the cit ...

(CSIR). He was also responsible for the Wadley Loop receiver, which allowed precision

tuning Tuning can refer to: Common uses * Tuning, the process of tuning a tuned amplifier or other electronic component * Musical tuning, musical systems of tuning, and the act of tuning an instrument or voice ** Guitar tunings ** Piano tuning, adjusti ...

over wide bands, a task that had previously required switching out multiple

crystal oscillator A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable cloc ...

Principle

The tellurometer emits a microwave-frequency

radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...

. 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 word, blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a T ...

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

modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...

. The resulting

phase shift In physics and mathematics, the phase of a 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 denoted \phi(t) and expressed in such a scale that it v ...

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 ( oscilloscope), pictu ...

with circular sweep.

Application

The tellurometer design yields high accuracy distance measurements over

geodetic Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

distances, but it is also useful for second order

survey Survey may refer to: Statistics and human research * Statistical survey, a method for collecting quantitative information about items in a population * Survey (human research), including opinion polls Spatial measurement * Surveying, the techniq ...

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 are a mountain range group of the Transantarctic Mountains System, located in the Ross Dependency region of Antarctica. They border on the western side of the Ross Ice Shelf, between Byrd Glacier and Nimrod Glacier. Seve ...

Cook Mountains The Cook Mountains is a group of mountains bounded by the Mulock and Darwin glaciers in Antarctica. Parts of the group were first viewed from the Ross Ice Shelf by the British National Antarctic Expedition (1901–04). Additional portions of t ...

Jacobsen Glacier Jacobsen Glacier () is a glacier flowing east-northeast from Mount Reid, in the Holland Range, Antarctica, into the Ross Ice Shelf. It was mapped by the United States Geological Survey from Tellurometer surveys (1961–62) and Navy air photos (19 ...

Mount Albright Albright may refer to: *Albright (surname) *Albright, Alberta, Canada *Albright, West Virginia, United States *Albright College, a liberal arts college located in Reading, Pennsylvania, United States *Albright–Knox Art Gallery, Buffalo, New York, ...

Mount Predoehl Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

Mount Summerson Summerson is a surname. Notable people with the surname include: * Hugo Summerson (born 1950), British politician * John Summerson (1904–1992), English architectural historian See also * Mount Summerson, mountain surmounting the northern end ...

, Sherwin Peak and

Vogt Peak During the Middle Ages, an (sometimes given as modern English: advocate; German: ; French: ) was an office-holder who was legally delegated to perform some of the secular responsibilities of a major feudal lord, or for an institution such as ...

. 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 oil exploration/offshore oil drilling and related activities. Strong emphasis is placed ...

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; ; french: Armée de la république du Viêt Nam) composed the ground forces of the Republic of Vietnam Military Forces, South Vietnamese military from its inception in 1955 to the Fall of Saigon in April ...

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. ** Britishness, the British identity and common culture * British English, ...

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 where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...

s for the product.

References

{{reflist Surveying instruments Science and technology in South Africa Length, distance, or range measuring devices South African inventions Microwave technology