UNIT 1 Geodetic Surveying & SBPS

1. UNIT 1Geodetic Surveying & SBPS MR. GORDE PRAVIN JAYSING CIVIL DEPARTMENT DYPIEMR, Akurdi.

2. Geodetic surveying • It is a branch of surveying which accounts for the curvature of the earth, as the area to be covered is large and the distances to be measured are also long. • Is also called as trigonometrical surveying

3. Object:- • It is establish Horizontal control and Geodetic leveling. • Is to fix vertical control throughout the area with highest degree of precison. • i.e. 3D control – Latitude, longitude and elevation above MSL. • very precise. • Very accurate • By survey of India Department. • Accurately locate centre lines terminal points of project.

4. Relative and Absolute position of point • Absolute position – one point, latitude and longitude • Relative position – Locating position of given point

5. Methods of establishing horizontal controls • Triangulation • Precise Theodolite traversing • Trilateration • Triangula-teration (triangulation + trilateration) • Precise E.D.M traversing

6. Triangulation • Principle- In triangle, if length of one side and three angles are known. • Sine rule. • well conditioned triangle. • Purpose –determine size and shapes of earth by carrying out observations for latitude and longitude and gravity. • Its provides accurately located system of horizontal controls on which less precise triangles established. • It helps fixing shaft centre line terminal points.

7. Fig.

8. The method of measuring the chain angles of a framework triangle being formed by marking station on the surface of earth. • Rapid and economical for narrow strip e.g highway, river, valley . • Not less than 30 and greater than 120 angles. • It provides most accurate and precise system of horizontal control.

9. Precise theodolite traversing • When triangulation is not possible Theodolite is used . • For large area it is inconvenient and time consuming. • Drawback is accumulation of error be come much more as compare to triangulation. • In the travels bearing and lengths are measured • Small and fairly flat area calculated easily.

10. Trilateration • It is series of connected triangles covering the entire area to be surveyed in which the lengths of all sides triangles are measured with high degree of precision by E.D.M • No angular measurements • High purchase cost. • No exact checks

11. triangulateration • Combination of triangular and trilateration. • Greater accuracy of work. • Lengths and angles are measured. • Effective and easy check.

12. Precise E.D.M traversing • No need of inter visibility • Less time less efforts • No requirement of site selection. • Initial cost is high • Easy to use. • No need of reconnaissance survey of area.

13. Triangulation system • A triangulation figure is defined as group or system of triangles arranged in such a way that any fig. has only one side common to each of the preceding.

14. A)chain of single triangles. For narrow width, long length Rapid and economical. Simple but less accurate.

15. B)chain of double trianglesArrangement of double triangles Checks are given accurately and rapid.Large area covered

16. C) Braced Quadrilateral • 4sided figure quadrilateral – with 4 corner station and observations made along both of the diagonals without any central station. • In this system no. of conditions to be satisfied • Different combinations of sides and angles • Preferred for long and narrow areas.

18. Centered figure • Considered triangles, quadrilateral , pentagons hexagons with central station. • Large area covered • Long and wide areas

19. Triangulation frame for extensive large area • Grid iron system – two series of chain of triangles. • One chain of triangles run through direction of meridian. • Area enclosed and surveyed with grid or network of small triangles. • System adopted for Extensive area survey. • All are well shaped triangles.

21. Criteria for selection of best triangulation fig. or system • Very long and short lines should be avoided. • It should be possible to calculate the side of triangles. • Well conditioned triangles used for area. • Triangles as far as equilateral. • Minimum station and maximum condition. • Arrangement of fig. should satisfactory and accuracy in computation work obtained. • Not to small and not to long area.

22. Selection of station • Station should be visible from one another. • Station having well conditioned triangle. • Lengths of survey not too long. • Easily accessible. • Stations should be economical. • Station with survey line roughly leveled. • Triangles with check lines easily located or established.

23. Classification of various triangulation system

24. Indivisibility and Height of station • Selection of triangulation station is important as relevant adjacent stations are intervisible. • It can be done by contour map. • If there is no intervening obstruction to line of sight, distance of visible horizon from station of known elevation. • h= D2/2R (1-2m) • Where, h= height of station above datum • R= Radius of earth= 6367km • D= distance of visible horizon in Km. • m= mean coe. Of refraction (0.07- land, 0.08- sea)

25. Space based positioning system (SBPS) • Is the technique of determining exact position of any point on Land, Sea and air around earth with help of satellite in any time(day and night). • Tracking of Position of object like moving vehicle, walking person, train route updation. • Location, speed, direction and time. • Used to map making, land surveying. • The technology collects and processes signals from satellites.

26. Advantages • No line of sight required. • No intervisibility , no angular or linear measurement. • No plumb line required. • No references. • 3D geocentric co-ordinate system. • High positional accuracy . • Rapid speed of work. • Digital output, easy to adjust.

27. Segments of SBPS • a) Space- Systematically arranged constellation of sufficient number of such synchronous and earth pointing satellite in near circular orbit, this circuit ensure that at least 4 satellite in view from any point of earth at any time of day. • Constellation- A group of stars on the celestial sphere as a fig. or design or an easily recognized group of stars that appear to be located close together in the sky and that forms a picture if lines connecting them are imagined.

29. GPS Satellite transmit a signal with 3 component • 1. Two sine waves – carrier frequencies • 2. Two digital PRN – (Pseudo Random Noise) • 3. A navigational message • The navigational message contains, along with other information the position information of satellite as function of time. • The transmitted signals are controlled by highly accurate and stable atomic clock fitted on satellite.

30. Space segment – consist satellite, coded ranging signals, position information, Atmosphere dates. • Control segment – consist master control station, few monitoring station and uploading antennas. • User segment – Users and their satellites, GPS receiver to receive GPS signals and determine their position and or time. Load navigation, vehicle location, surveying , marine navigation, Aerial navigation machinery control. 4 satellites , 3D – Velocity, position, system and time.

31. GPS- Global positioning system • US technology. • 24 + 4 NAVSTAR (Navigational satellite Time and Ranging ) • 12 hour orbit around earth. • 1990 arrangement such as at least 4 satellites available 24 hours of a day, above horizon angle 55 to equatorial plane. • Helps to identify location of natural disaster like landslides, earthquake, flood, cyclones effectively.

32. Features – • Sun synchronous and earth pointing • 12 hour near circular orbit • 20200 km above earth • Global coverage • All weather operation • 5yrs design life • 430 to 680 kg orbit weight • Power source 5m2 solar array and 3 Nicd • 3 axis stabilized

34. b) GLONASS – Global Navigation and surveying system • Russian space based positioning system • Similar to NAVSTAR • 24 operational satellite in 3 nearly arranged circular orbit. • Apart from altitude 19100 km, inclined t 64.80 to equator. • Spacing between satellite one orbital plane is 45 0 • Ensure 5 satellite always in visible horizon

35. Comparison of positional system • Constellation GPS Glonass Galileo • Total satellite 24 + 3 24 + 4 27 + 3 • Orbital height 20200 19100 23616 • Orbital period 12 Hrs 11.15 Hrs 14hrs32min • No. of orbital plane 6 3 3 • Satellite in each plane 4 8 10 • Inclination with equator 550 64.80 560 • Orbital plane angle 600 1200 1200

36. Gagan-GPS Aided GEO Augmented Navigation • Indian satellite based navigation system. • Launched- 2011-12, Life of operation- 15 years • Improved accuracy of GNSS receiver. • Used to modern communication, Navigation, surveillance, air traffic management. • Bangalore centre base station, 3m accuracy • Flight management system- It will improve airport and airspace access in all weather condition. • Karnataka forest area used to control animals movement.

38. Compass- beidou • China based regional satellite based navigation system. • Launched- 2011. • Period- 12.63 hrs • Geostationary orbit. • 15 satellite operational.

39. Positioning SBPS • Principle is resection • Range – distance of SBPS receiver from such satellite is known as range. • At least 3 ranges w.r.t. 3 Independent satellite above its horizon. • 4th satellite – clock errors.

40. Methods – • 1. Absolute - static and kinematic. • 2 Differential - Static and kinematic. • These all done for real time data • E.g. TV and Radio Live commentary, Channel wise live recording, seconds difference whatsapp service, Google maps

41. a) Absolute – • Only one GPS receiver receive signals from 4 satellites to determine own co-ordinates wrt center of earth. • PPS – Precise positioning system • SPS – Standard positioning system • It is code based technique • PPS – military and authorized users. • SPS – civil community CIA code precise @50m

42. Differential • Two receivers. • Master base –simultaneously tracking same. • Rover – satellite to determine position. • Master- stable at point. • Rover – not stable. • It relative positioning. • Used for hydrographic survey , basic land survey.

43. Basic components of SBPS Receiver • Antenna – Radio frequency. • Signal identification and processing . • Microprocessor – control GPS operation. • Precision oscillator = clock errors. • Power supply – Ni-cd battery. • Memory.

44. Factors Governing Accuracy in SBPS • 1) The Ephemeris –The position data about satellites , which is known as ephemeris available in coded form in signals transmitted by satellite. • 2) DOP- Dilution geometry has direct effect on satellite accuracies. The best signals point positioning accuracies are achieved when satellites have good spatial distribution in sky. • 3) Access denial techniques – a) selective availability – ranges. • b) Anti-sphoofing – The Intent was to prevent enemy from transmitting false GPS signal which could confuse or misdirect friendly wars.

45. Sources in errors in SBPS • Orbital errors – Difference between satellite position as calculated using broadcast true position of satellite in space errors upto 2.5 m. • Satellite clock errors – 1.5 m • Atmospheric errors – • Multiple – Reflected signals • Receiver clock errors • Receiver noise errors.

46. Applications of SBPS • Connects network in unreachable areas. • Polar motion study. • Earthquake monitoring. • Geophysical positioning , mineral exploration and mining. • Establishing control for topographic and cadastral survey. • Ground control for photogrammetry. • Positioning offshore structure ship, boats. • Space craft tracking/ navigation land, water, air. • Improve military weapon delivery accuracies.

47. Thank You….