If the gyro theodolite is used, the azimuth datum with absolute high accuracy can be obtained, and it can reduce the expensive testing operation (the least. Gyro-theodolites are primarily used in the absence of astronomical star sights and GPS. For example, where a conduit must pass under a river, a vertical shaft on. This thesis comprises a study of the gyroscope and the gyrotheodolite, tunnel control networks and a case study of geodetic reference networks and survey.
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In surveyinga gyrotheodolite also: It is used to determine the orientation of true north. It is the main instrument for orientation in mine surveying  and thheodolite tunnel engineering, where astronomical star sights are not visible and GPS does not work.
This principle was adapted by Max Schuler in to build the first surveying gyro. Inthe gyro-theodolite — at that time called a “meridian pointer” or “meridian indicator”  — was first used by the Clausthal Mining Academy underground. Several years later it was improved with the addition of autocollimation telescopes. Inthe Fennel Kassel company produced the first of the KT1 series of gyro-theodolites. A gyroscope is mounted in a sphere, lined with Mu-metal to reduce magnetic influence, connected by a spindle to the vertical axis of theodolire theodolite.
The battery-powered gyro wheel is rotated at 20, rpm or more, until it acts as a north-seeking gyroscope. By tracking the spin axis as it oscillates about the meridian, a record of the azimuth of a series of the extreme stationary points of that oscillation may be determined by reading the theodolite azimuth circle.
A midpoint can later be computed from these records that represents a refined estimate of the meridian.
Careful setup and repeated theodolitte can give an estimate that is within about 10 arc seconds of the true meridian. These errors can be moderated by refining the initial estimate of the meridian to within a few arc minutes and correctly aligning the zero torque of the suspension.
This is because the daily rotation of the Earth is in effect continuously tilting the east-west axis of the station. The spinner axis then theoddolite towards and overshoots the meridian, it then slows to a halt at an extreme point before similarly swinging back towards the initial point of release. This oscillation in azimuth of the spinner axis about the meridian repeats with a period of a few minutes.
In practice the amplitude of oscillation will only gradually reduce as energy is lost due to the minimal theoxolite present. When not in operation, the gyroscope assembly is anchored within the instrument. The electrically powered gyroscope is started while restrained and then released for operation.
During operation the gyroscope is supported within the instrument assembly, typically on a thin vertical tape that constrains the gyroscope spinner axis to remain horizontal.
The alignment of the spin axis is permitted to rotate in azimuth by only the small amount required during gyto. An initial approximate estimate of the meridian is needed.
Gyrotheodolite – WikiVisually
This might be determined with a magnetic compassfrom an existing survey network or by the use of theodolte gyro-theodolite in an extended tracking mode. Gyro-theodolites are primarily used in the absence of astronomical star sights and GPS. For example, where a conduit must theoxolite under a river, a vertical shaft on each side of the river might be connected by a horizontal tunnel. A gyro-theodolite can be operated at the surface and then again at the foot of the shafts to identify the directions needed to tunnel between the base of the two shafts.
Although a gyro-theodolite functions at the equator and in both the northern and southern hemispheres, it cannot be used at either the North Pole or South Polewhere ttheodolite Earth’s axis is precisely perpendicular to the horizontal axis of the spinner and the meridian is undefined.
Unlike an artificial horizon or inertial navigation system, a gyro-theodolite cannot be relocated while it is operating. It must be restarted again at each site.
When available, astronomical star sights are ttheodolite to give the meridian bearing to better than one hundred times the accuracy of the gyro-theodolite. Where this extra precision is not required, the gyro-theodolite is able to produce a result quickly without the need for night observations.
Surveying — Surveying or land surveying is the technique, profession, and science of determining the terrestrial or three-dimensional position of points and the distances and angles between them. A land surveying professional is tehodolite a land surveyor, Surveyors work with elements of geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages and the law.
Surveying has been an element in the development of the environment since the beginning of recorded history. The planning and execution of most forms of construction require it and it is also used in transport, communications, mapping, and the definition of legal boundaries for land ownership. It is an important tool for research in other scientific disciplines. Basic surveyance has occurred since humans built the first large structures, the prehistoric monument at Stonehenge was set out by prehistoric surveyors using peg and rope geometry.
In ancient Egypt, a rope stretcher would use simple geometry to re-establish boundaries after the floods of the Nile River. The almost perfect squareness and north-south orientation of the Great Pyramid of Giza, built c. The mathematician Liu Hui described ways of measuring distant objects in his work Haidao Suanjing or The Sea Island Mathematical Manual, the Romans recognized land surveyors as a profession.
They established the basic measurements under which the Roman Empire was divided, Roman surveyors were known as Gromatici. In medieval Europe, beating the bounds maintained the boundaries of a village or parish and this was the practice of gathering a group of residents and walking around the parish or village to establish a communal memory of the boundaries.
Young boys were included to ensure the memory lasted as long as possible, in England, William the Conqueror commissioned the Domesday Book in Theodollte recorded the names of all the owners, the area of land they owned, the quality of the land. It did not include maps showing exact locations, abel Foullon described a plane table inbut it is thought that the instrument was in use earlier as his description is of a developed instrument.
Gunters chain was introduced in by English mathematician Edmund Theoodolite and it enabled plots of land to be accurately surveyed and plotted for legal and commercial purposes. Leonard Digges described a Theodolite that measured horizontal angles in his book A geometric practice named Pantometria, joshua Habermel created a theodolite with a compass and tripod in Johnathon Sission was the first to incorporate a telescope on a theodolite inin the 18th century, modern techniques and instruments for surveying began to be used.
Jesse Ramsden introduced the first precision theodolite in and it was an instrument for measuring angles in the horizontal and vertical planes. Theodolites are used mainly for surveying applications, and have adapted for specialized purposes such as meteorology.
A modern theodolite consists gro a telescope mounted within two perpendicular axes, the horizontal or trunnion axis and the zenith axis. A theodolite measures vertical angles as angles between the zenith, forwards or plunged—typically approximately 90 and degrees, when the telescope is pointed at a target object, the angle of each of these axes can be measured with great precision, typically to seconds of arc.
A theodolite may be either transit or non-transit, in a transit theodolite, the telescope can be inverted in the vertical plane, whereas the rotation in the same plane is restricted to a semi-circle in a non-transit theodolite. Some types of transit theodolites gyroo not allow the measurement of vertical angles, the builders level is sometimes mistaken for a transit theodolite, but it measures neither horizontal nor vertical angles.
It uses a gyto to set theodoolite telescope level to define a line of sight along a horizontal plane. A theodolite is mounted on its head by means of a forced centering plate or tribrach containing four thumbscrews, or in modern theodolites. Before use, a theodolite must be placed vertically above the point to be measured using a plumb bob. The instrument is then set level using leveling footscrews and circular, both axes of a theodolite are equipped with graduated circles that can be read through magnifying lenses.
Half of the difference between the two positions is called the index error, the horizontal and vertical axes of a theodolite must be perpendicular, if not then a horizontal axis error exists.
This can be tested by aligning the tubular spirit bubble parallel to a line between two footscrews and setting the bubble central, a horizontal axis error is present theofolite the bubble runs off central when the tubular spirit bubble is reversed. If not, then a collimation error exists, index error, horizontal axis error and hheodolite error are thheodolite determined by calibration and are removed by mechanical adjustment.
Their existence is taken account in the choice of measurement procedure in order to eliminate their effect on the measurement results of the theodolite. The term diopter was used in old texts as a synonym for theodolite. This derives from an astronomical instrument called a dioptra. The GPS system operates independently of any telephonic or internet reception, the GPS system provides gyor positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, however, the US government can selectively deny access to the system, as theodolitf to the Indian military in during the Kargil War.
Department of Defense developed the system and it became fully operational in In addition to GPS, other systems are in use or under development, mainly because of a denial of access. There are also the European Theodolitd Galileo positioning system and Chinas BeiDou Navigation Satellite System, special and general relativity predict that the clocks on the GPS satellites would be seen by the Earths observers to run 38 microseconds faster per day than the theodoliye on the Earth.
The GPS calculated positions would quickly drift into error, accumulating to 10 kilometers per day, the relativistic time effect of the GPS clocks running faster than the clocks on earth was corrected for in the design of GPS. It used a constellation of five satellites and could provide a navigational fix approximately once per hour, inthe U.
Navy developed the Timation satellite, which proved the feasibility of placing accurate clocks in space, a technology required by GPS.
In the s, the ground-based OMEGA navigation system, based on comparison of signal transmission gro pairs of stations. Limitations of these systems drove the need for a more gyeo navigation solution with greater accuracy, during the Cold War arms race, the nuclear threat to the existence of the United States was the one need that did justify this cost in the view of the United States Congress.
This theoolite effect is why GPS was funded and it is also the reason for the ultra secrecy at that time. Compass — A compass is an instrument used for navigation and orientation that shows direction relative to the geographic cardinal directions, or points.
Usually, a called a compass rose shows the directions north, south, east. When the compass is used, the rose can be aligned with the geographic directions, so, for example. Frequently, in addition to the rose or sometimes instead of it, North corresponds to zero degrees, and the angles increase clockwise, so east ttheodolite 90 degrees, south isand west is These numbers allow the compass to show azimuths or bearings, which are stated in this notation.
The magnetic compass was first invented as a gyrl for divination as early as the Chinese Han Dynasty, the first usage of a compass recorded in Western Europe and the Islamic world occurred around the early 13th century.
The magnetic compass is the most familiar compass type and it functions as a pointer to magnetic north, the local magnetic meridian, because the magnetized needle at its heart gyto itself with the horizontal component of the Earths magnetic field.
The needle is mounted on a pivot point, in better compasses a jewel bearing. When the compass is level, the needle turns until, after a few seconds to allow oscillations to die out.
In navigation, directions on maps are usually expressed with reference to geographical or true north, the direction toward the Geographical North Pole, the rotation axis of the Earth. Depending on where the compass is located on the surface of the Earth the angle between north and magnetic north, called magnetic declination can vary widely with geographic location. The local magnetic declination is given on most maps, to allow the map to be oriented with a parallel to true north.
The location of the Earths magnetic poles slowly change with time, the effect of this means a map with the latest declination information should be used. Some magnetic compasses include means to compensate for the magnetic declination. The first compasses in ancient Han dynasty China were made of lodestone, the compass was later used for navigation during the Song Dynasty of the 11th century.
Later compasses were made of iron needles, magnetized by striking them with a lodestone, dry compasses began to appear around in Medieval Europe and the Islamic world. This was supplanted in the early 20th century by the magnetic compass. Modern compasses usually use a needle or dial inside a capsule completely filled with a liquid. Channel Tunnel — At its lowest point, it is 75 m deep below the sea bed, and m below sea level. The speed limit for trains in the tunnel is kilometres per hour, the tunnel carries high-speed Eurostar passenger trains, the Eurotunnel Shuttle for road vehicles—the largest such transport in the world—and international freight trains.
The tunnel connects end-to-end with the LGV Nord and High Speed 1 high-speed railway lines, ideas for a cross-Channel fixed link appeared as early asbut British political and press pressure over the compromising of national security stalled attempts to construct a tunnel. An early attempt at building a Channel Tunnel was made in the late 19th century, the eventual successful project, organised by Eurotunnel, began construction in and opened in Both fires and cold weather have temporarily disrupted its operation, illegal immigrants have attempted to use the tunnel to enter the UK, causing a minor diplomatic disagreement over the siting of the refugee camp at Sangatte, which was eventually closed in Ina deputation led by George Ward Hunt proposed the idea of a tunnel to the Chancellor of the Exchequer of the day, aroundWilliam Low and Sir John Hawkshaw promoted ideas, but apart from preliminary geological studies none were implemented.