ADS_ Modern Survey Techniques by KRT .ppt

1
Prepared By:
Mr. K.R.THANKI
Mr. K.R.THANKI
(BE Civil)
(BE Civil)
LECTURER CIVIL ENGINEERING DEPARTMENT
LECTURER CIVIL ENGINEERING DEPARTMENT
GOVERNMENT POLY TECHNIC ,
GOVERNMENT POLY TECHNIC ,
PORBANDAR,GUJARAT-INDIA.
PORBANDAR,GUJARAT-INDIA.

2
COURSE OUTCOMES (COs):
COURSE OUTCOMES (COs):
1) Carry out a contour survey for undulating/hilly regions
using a Tacheometer and prepare contour map.
2) Setting out a horizontal curve using a theodolite.
3) Carry out traverse survey using total station, import the
data in the computer, and prepare drawing using Auto
CAD.
4) Record and retrieve the data using a Hand-Held GPS
5) Give a demonstration of the field procedure of
modern surveying equipments.

3
CONTENTS of UNIT :
CONTENTS of UNIT :

Introduction
Introduction :
• Modern surveying instruments are faster and more precise
than traditional instruments.
• Modern surveying instruments, such as Total Stations, GPS
devices, and 3D Laser Scanners, provide precise
measurements and data collection for land surveyors.
These advanced tools enable efficient data processing, real-
time mapping, and accurate topographical analysis,
revolutionizing the traditional surveying methods and
enhancing the overall quality of survey data.
4

GPS
GPS :
Global Positioning System which stands for Global Positioning
System, is the only system today able to show you your exact
position on the Earth anytime, in any weather, anywhere.
5

Global Positioning System (GPS): How it works
Global Positioning System (GPS): How it works:
6
• At least 24 operational
GPS satellites in orbit
– 12 hour orbit
– 11,000 miles above
earth
– Atomic clock
• Oscillations of a single
atom to determine time
– Synchronized, send
signals at same time
http://en.wikipedia.org/wiki/Gps

Global Positioning System (GPS):
How it works cont’d.
• Satellites send data to earth which are picked
up by a receiver
• Signals arrive at different times based on the
distance from the satellite
– L1 (1575.42 MHz)
• Receiver needs to determine
distance to four satellites
– Determines 3-dimensional
position
– Does not send out a signal
• But how does the receiver
determine its distance from
each satellite?
7

How it works cont’d.
• To calculate distance:
– Distance = Speed * Time
• Speed ≈ Speed of Light
• How to determine time?
– GPS receiver’s clock becomes synchronized to Coordinated
Universal Time by tracking four or more satellites
– Each satellite transmits a unique “pseudo random” code at
extremely precise time intervals
– Receiver knows each satellite’s pseudo random code and when
they are sent
– Receiver determines the time delay it takes to match the expected
satellite pseudo random code with the received pseudo random
code
• Time Delay = Time!
8

Sources of Error
• Speed of light is only a constant in a vacuum
– Atmospheric
• Charged Particles in the Ionosphere
• Water Molecules in the Troposphere
• Ephemeris errors
– Error that effects the satellite’s orbit (ephemeris)
– Caused by the gravitational pull of the sun, moon, and the
pressure caused by solar radiation
– Error monitored by the Department of Defense (DoD) and
broadcasted to the GPS satellites
• Multipath Error
– Timing error from signals bouncing off of objects such as
buildings or mountains
– Can be reduced by signal rejection techniques
• How can we reduce errors caused by the atmosphere? 9

Sources of Error
10

Sources of Error
11

Error Correction: DGPS
• DGPS = Differential GPS
• Basic Idea:
– Use known locations as reference locations
• Exact Position is known, compare to the location
determined by GPS
• Develop error correction data by using the difference of the
exact location and the GPS determined location
– Broadcast error correction data to local GPS receivers
(receivers within 200km of the reference station)
– Error correction can remove errors caused by the
atmosphere—makes GPS data more accurate!
12

13

14

Error Correction: WAAS
• Wide Area Augmentation System (WAAS)
– WAAS is an example of DGPS
– Also referred to as a Satellite Based Augmentation
System (SBAS)
– Developed by the Federal Aviation Administration
(FAA)
– Uses a network of ground based stations in North
America and Hawaii
– Measures variations in satellite signals
• Relays error to geostationary WAAS satellites
• Used to improve accuracy and integrity of data
– Independent systems being developed in Europe
(Galileo), Asia, and India.
16

17

18

Applications
• Aerospace
• Automotive
• Military
• Civilian
– Recreation
– Augmented Reality
• The list goes on
19

Differential GPS (DGPS)
Differential GPS (DGPS):
• Differential Global Positioning System is an enhancement to
the Global Positioning System (GPS) which provides
improved location accuracy, in the range of operations of
each system, from the 15 m nominal GPS accuracy to about
10 cm in case of the best implementations.
• The United States Coast Guard (USCG) and the Canadian
Coast Guard (CCG) each run DGPS in the US and Canada on
long wave radio frequencies between 285 kHz and 325 kHz
near major waterways and harbours.
• DGPS is a land based technology that works to improve the
accuracy of GPS system. This can yield efficient
measurements to 1-5 m in moving as well as stationary
situations. 20

• The DGPS involves the cooperation of two receivers , a
stationary one (Base receiver) and another is rover receiver.
21

22

23

24
Basis for Comparision GPS DGPS
Number of receivers
used
There is only one
standalone GPS receiver.
Two, Rover and
stationary receivers.
Cost GPS is less expensive
compared to DGPS.
DGPS is more expensive
than GPS.
Time Coordinate system
used
WGS84 (World Geodetic
System 1984 is a datum
featuring coordinates.)
Local coordinate system.
Frequency range 1.1-1.5 GHz Varies according to the
agency.
Range of the
instruments
Global Local (within 100 km)
Accuracy 15-10m 10cm
Factors Affecting the
Accuracy
Ionosphere, troposphere,
multipath, selective
availability, atmospheric
conditions, and satellite
timing are some of the
factors that affect the
accuracy.
Distance between the
transmitter and rover,
ionosphere, troposphere
and multipath are some
of the factors that affect
the accuracy.

Unmanned Arial Vehicle (UAV)
Unmanned Arial Vehicle (UAV):
25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43
Application of Drone/ UAV:
• Land surveying
• Land Management and Development
• Precise Measurements
• Stockpiles volumetric measurements
• Slope monitoring by Digital Terrain Modeling
• Urban planning

Geographic Information System (GIS)
Geographic Information System (GIS):
44
A Geographic Information System (GIS) is a computer
system that analyzes and displays geographically
referenced information. It uses data that is attached to
a unique location.

45
A geographic information system (GIS) is a computer
system for capturing, storing, checking, and displaying
data related to positions on Earth’s surface. GIS can
show many different kinds of data on one map, such
as streets, buildings, and vegetation. This enables
people to more easily see, analyze, and understand
patterns and relationships.

46

47

48

49

50

51

Softwares
52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

ADS_ Modern Survey Techniques by KRT .ppt

More Related Content

Similar to ADS_ Modern Survey Techniques by KRT .ppt (20)

More from Krunal Thanki (20)

Recently uploaded (20)

ADS_ Modern Survey Techniques by KRT .ppt

Editor's Notes