The tellurometer was the first successful microwave electronic distance measurement equipment. The name derives from the Latin tellus, meaning Earth.
The tellurometer was the first successful microwave electronic distance measurement equipment. The name derives from the Latin tellus, meaning Earth.
The original tellurometer, known as the Micro-Distancer MRA 1, was introduced in 1957. [1] It was invented by Trevor Wadley of the Telecommunications Research Laboratory of the South African Council for Scientific and Industrial Research (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 oscillators. [2]
The tellurometer emits a microwave-frequency radio wave. The remote station carries a transponder that reradiates the incoming wave in a similar wave of more complex modulation. The resulting phase shift is a measure of the two-way distance travelled. The results appear on a cathode ray tube with circular sweep. [3]
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 is 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. [4]
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. [5]
The MRB2 or Hydrodist was a marine version that was used in coastal hydrographic surveys and calibrating ships using other survey navigation systems. [5]
They were used by the Army of the Republic of Vietnam in the late 1960s. [6]
Plessey, the British electronics company, formed a new subsidiary known as Tellurometer (Pty) Limited in the 1960s to manufacture the product and to develop and sell derivatives. [5] The company subsequently introduced numerical displays, solid state transmitters, integrated circuits and eventually microprocessors for the product. [5]
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 ranges as microwaves; the above broad definition includes both UHF and EHF bands. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz. In all cases, microwaves include the entire SHF band at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations.
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is called a land surveyor. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designed positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales.
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for amateur radio communications, international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems.
Super high frequency (SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz (GHz). This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres. These frequencies fall within the microwave band, so radio waves with these frequencies are called microwaves. The small wavelength of microwaves allows them to be directed in narrow beams by aperture antennas such as parabolic dishes and horn antennas, so they are used for point-to-point communication and data links and for radar. This frequency range is used for most radar transmitters, wireless LANs, satellite communication, microwave radio relay links, satellite phones, and numerous short range terrestrial data links. They are also used for heating in industrial microwave heating, medical diathermy, microwave hyperthermy to treat cancer, and to cook food in microwave ovens.
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 companies.
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Trevor Lloyd Wadley, 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.
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