1. NPR COLLEGE OF ENGINEERING &
TECHNOLOGY,
DINDIGUL
DEPARTMENT OF CIVIL ENGINEERING
GI-8013-ADVANCED SURVEYING-III-CIVIL
PRESENTED BY,
MRS.S.PREMASUNDARI
ASSISTANT PROFESSOR
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2. UNIT III- TOTAL STATION SURVEYING
9 HOURS
Classification – basic measuring and working
principles of an Electro – optical and
Microwave total station- sources of errors in
Electro – optical and Microwave total station –
Care and Maintenance of total station –
trilateration – Applications.
3. • It is an optical instrument used in
modern surveying.
It is a combination of an electronic
theodolite and electronic distance
meter and software running on an
external computer know as data
collector.
TOTAL STATION-EFINITION
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4. Distance measuring instrument (EDM)
Angle measuring instrument(Thodolite)
A simple processor
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It consists of the following,
5. Based on Wavelength
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Classifications
7. 1.Manual
Horizontal and vertical angles can be measured manually
and slope distance by electronically .
2.Semo-automatic
Horizontal angle-Manually
Vertical angle-Digitally,
Slope distance-Electronically
3.Automatic
Horizontal ,Vertical angle and slope distance measured
electronically.
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TYPES OF TOTAL STATION
8. Basic Principles:
The Determination of time required for electromagnetic
waves to travel between two station.
Electro magnetic energy propagates through to
atmosphere in accordance with the following equation.
V = f λ
Where,
V- Velocity of Electro magnetic energy (m/s)
f- Modulated frequency of the energy (HZ)
λ- Wavelength(m)
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Principles of EDM instruments
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• EDM is very useful in measuring distances that are
difficult to access or long distances.
It measures the time required for a wave to sent to a
target and reflect back.
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• A wave is transmitted and the
returning wave is measured to
find the distance traveled.
11. Distances determined by calculating the number of
wavelengths traveled.
Errors are generally small and insignificant for short distances.
For longer distances they can be more important.
Errors can be accounted for manually, or by the EDM if it has
the capability.
Velocity of light can be affected by:
Temperature
Atmospheric pressure
Water vapor content
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13. The general principle involves sending a modulated Electro-
magnetic (EM) beam from one transmitter at the master
station to a reflector at the remote station and receiving it
back at the master station.
The instrument measures slope distance between
transmitter and receiver by modulating the continuous
carrier wave at different frequencies, and then measuring
the phase difference at the master station between the
outgoing and the incoming signals. This establishes the
following relationship for a double distance (2D):
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1.Pulse method
15. The measured distance is calculated from the
velocity of the signal multiplied by the time.
2D=c.∆t
D=c.∆t /2
C=the velocity of light in the medium
through which it travelled.
D=the distance between the instrument
and target.
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Pulse method
16. The EDM instruments mostly used this form of
measurement.
The instrument measures the amount (λ) by
which the reflected signal is out of phase with
the emitted signal.
The double distance is equal to the number of full
wavelength(λ) plus the fraction of
wavelength(λ).
2D=mλ+λ
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2.Phase difference method
20. Depending on the type of carrier wave employed,
EDM instruments can be classified under the following
three heads:
(a) Microwave instruments(Tellurometer)
(b)Visible light instruments(Geodimeter)
(c) Infrared instruments(Distomats)
TYPES OF EDM INSTRUMENTS
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21. Main Types:
Electro-Optical Instruments: Use the light and infrared
waves.
Microwave Instruments: Use the radio waves.
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22. *These instruments under the category of long
range instruments,
*where in the carrier frequencies of the range
of 3 to 30GHz(1 GHZ=10^9)
*Distance measurements upto 100 km
range(30 km to 80 km).
(eg)Tellurometer
1.MICROWAVE INSTRUMENTS(Tellurometer)
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24. *It works based on propagation of radio
waves.
*Invented in 1950’s in south africa –T.L.Wadley.
*It can be used both during day and night.
*Phase comparison technique is used for
distance measurement.
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25. *2 instruments
Reflector-@ the remote end of the line.
Master instrument-Passive reflector-@the other end
* Remote instrument- An electrical signal is required to be
erected @ the reflecting end of the line.
It receives the transmitted signal, amplifies it and
transmits it back to the master.
*Master instrument-Placed @ measuring end.
*This means that microwave EDM instruments require two
instruments and two operators.
*Frequency modulation is used microwave instruments.
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26. *High frequency radio waves( or microwaves) are used
instead of light waves.
*worked with a light weight-12 or 24 volt battery.
*instrument –highly portable
*Observations- during day as well as night.
*2 such tellurometers are required
*one to be stationed @ each end of the line
*2 highly skilled persons, to take observations.
TELLUROMETER
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27. *1 instrument-master set or control set.
*other instrument-remote set or slave set.
*Model- MRA-2(Manufactured by
M/s.Cooke, Troughton and Simms Ltd).
*each set –master set or remote set by
switching at ‘master’ and ‘remote’ positions
respectively.
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29. *Radio waves are emitted by the master instrument at a
frequency of 3000 Mc.s (Modulation coding schemes)
from a klystron and have superimposed on them a
crystal controlled frequency of 10 Mc.s.
*The high frequency wave is termed as carrier wave.
*Waves at high frequencies can be propagated in
straight line paths.
*Waves at low frequency wave is known as pattern
wave-used for accurate measurements.
Carrier wave
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30. *The light frequency pattern wave is thus
said to be frequency modulated(F.M.) by low
frequency pattern wave.
*This modulated signal is received at the
remote station where a second klystron is
generating another carrier wave at 3033 Mc.s.
Frequency modulated wave:
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31. *The difference between the two high
frequencies,
*3033-3000=33 Mc.s– is obtained by
electrical mixer,
*used to provide sufficient sensitivity in the
internal detector circuits at each instrument.
INTERMEDIATE FREQUENCY
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32. Developed in the year of 1957.
2 functions of tellurometer.
(i) Master mode (ii)Remote mode
major difference b/w electro optical EDM
& Micro wave EDM.
PRESENCE OF A PARABOLIC OR HORN
RADIO ANTENNA & THE ABSENCE OF
OPTICAL PARTS
WORKING PRINCIPLE
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33. OSCILLATOR
It can be switched through different quartz
crystals to produce modulation frequencies.
Klystron
*Electronic tube producing a microwave.
*Antenna- parabolic shape &2 small diapoles
@its focus.
*There are perpendicular to each other-45º
vertical.
*Transmitted and received signals are polarized.
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34. DEMODULATORS:
Demodulate amplitude modulated signals into
alternating currents.
TO OBTAIN A DISTANCE MEASUREMENT
THE MASTER AND REMOTE STATIONS TRANSMIT
FREQUENCY MODULATED SIGNALS AT SLIGHTLY
DIFFERENT FREQUENCIES OF CARRIER AND
MODULATION.
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35. *Two operators are needed to measure a
line.
*Sometimes there is difficulty to set up two
units on both sides.
*The accuracy is affected by the
atmosphere.
*Less accuracy than the electro-optical
type.
Disadvantages of Microwave Type
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36. *It works based on the propagation of light waves.
*This type of instrument was first developed in Sweden
and was named as Geodimeter.
*During night its range is up to 2.5 km while in day its
range is up to 3 km
*Accuracy of these instruments varies from 0.5 mm to 5
mm/km distance.
*These instruments are also very useful for civil
engineering projects.
2.GEODIMETER-ELECTRO OPTICAL
INSTRUMENTS(Visible Light Wave Instruments)
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37. *Model 2 A-Night time only.
*Model-4-limited day time
observations.
*Instrument-@one end
*Reflector-@other end
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38. *Use the velocity of light waves to determine
the distance between two points.
*Those instruments use both the visible lights
(wavelength between 0.4-0.7) and
* the infrared lights
(wavelength between 0.7-1.2).
*Infrared light much preferable because of the
long wavelength.
*Source of light: Mercury lambs, Tungsten.
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41. 1.Incandescent lamp:
The light from an incandescent
lamp is focused by means of an
achromatic condenser(four lens
elements) and passed through a
Kerr cell.
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42. *The Kerr cell consists of two closely spaced
conducting plates.
*The space between which is filled with
nitrobenzene(applying a voltage to the fluid).
*When high voltage is applied to the plates of the
cell and a ray of light is focused on it,
*The ray is split into 2 parts, each moving with
different velocity.
2.Kerr cell
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43. *2 Nicol’s prism are placed on either side of the Kerr cell.
*The light leaving the first Nicol’s prisms is plane
polarized(Vibration).
*The light is split into two (phase difference) by the Kerr
cell.
*On leaving the Kerr cell, the light is recombined.
*Because of phase difference is resulting beam is
elliptically polarised.
3.Nicol’s Prisms(used generate polarized light)
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44. *Diverging light from the second polariser can be focused
to a parallel beam by the transmitter objective,&
*Then be reflected from a mirror lens to a large spherical
concave mirror.
On the other hand,
*A spherical mirror, which reflects the beam of light back
to the geodimeter.
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45. It consists of the following,
*Spherical concave mirror
*Mirror lens
*Receiver objective
Receiver system
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46. *The light of variable intensity after
reflection ,affects on the cathode of the
photo tube.
*In the photo tube, the light photons affects
on the cathode causing a few primary
electrons to leave and travel,accelerated by a
high frequency voltage, to the first dynode,
4.Photo tube
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47. *where the secondary emission takes
place.
*This is repeated through a further
eight dynode.
*The final electron current at the
anode is some hundreds of thousand
times greater than that at the
cathode. 1/7/2021
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48. The passages of this modulating
voltage through the instrument is
delayed by means of an adjustable
electrical delay unit.
5.Variable eletrical delay unit
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49. The difference between the
phototube currents during the
positive the negative bias period
is measured on the null indicator.
6.Null indicator
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50. The variation in the intensity of
this reflected light causes the
current from the photo multiplier to
vary ,
where the current is already
being varied by the direct signal
from the crystal controlled
oscillator.
7.oscillator
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51. The phase difference between
the 2 pulses received by the cell are
a measure of the distance between
geodimeter and the reflector
(Length of the line).
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52. Prism reflector:
It is a combination of ranging rod, staff
and and optical cuboidal mirror.
having 2/3 lifts with 5cms interval
graduations.
adjustable height from 1.5m to 3.75m.
More number of prisms, will give more
accuracy.
Basic components of Total station
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54. GUN: data screen LCD
eye piece
telescope 24x to 43x
environmental box
microprocessor with memory card of 1 or 2 GB capacity
1MB can store 800 points.
Tripod: with different material
Aluminum tripod weighs 13 to 14lbs
Wooden tripod will be about 18 lbs.
Optical and Laser plumb bobs.
Battery –as an external attachment
with indicators
1.5hours charged battery can work for 3to 5 hours
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Functions of T.S:
1. It simultaneously measures angles & distances and Record
2. Correcting the measured distance with:
1. Prism constant
2. Atmospheric Pressure
3. Temperature
4. Curvature of earth
5. Refraction correction
3. Computing the point elevation
4. Computing the coordinates of every point
5. Remote elevation measurement
6. Remote distance measurement
7. Area calculations
8. Data Transferring facility from instrument to S/W and S/W
to instrument
9. Format of conversion of units
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Operations involved while using Total Stations :
1. Establishing the site Datum:
a) Selecting the site Datum
b) Establishing North
2. Setting up the Total station:
a) Placing and leveling Tripod on Datum
b) Placing and leveling the Gun on Tripod
c) Linking the data connector to Gun
3. Data collector options and setting
a) Main menu
b) Basic settings
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4. Creating and Operating Job files:
a) Creating a new Job file
b) Opening an existing file
5. Shooting points
a) Identifying the important points to shoot
b) shooting points
c) Shooting additional points
d) Noting the special features
6.Post Processing – Data down loading,conversion
7.Plotting/Map generation.
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Computer software packages
The following post processing computer software packages
are in use for various engineering applications.
1.Arc Pad, arc view, arc info
-conversion from raster to vector form
2.Micro Station - Map generation
3.Erdas – Image processing s/w
4.Surfer, Auto plotter, Civil cad, Pythagarus
– preparation of contours
5. Survey aid – to draw c/s and l/s
The information received is to be analyzed depending on the
users requirement.
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Limitations:
• It is not a Rugged instrument (Sensitive).
• Prism verticality is questionable.
• Visibility is must.
• More Expensive.
• Requires calibration at every six months.
• Amount of error is greater at short distances.
• Height of instrument and prism is to fed.
• Awareness on battery maintenance.
• To establish north- compass is required.
62. Have keen observation on the prism boy’s attitude. When
high precision is required, use the prism tripod, to avoid
human error.
The position of prism shall always be on hard surface
instead of soft soil.
Focusing shall be exactly at the centre of prism, with
the help of cross hairs and prism plate.
While measuring the instrument height and prism height,
enough attention shall be diverted. Also, have keen
observation while entering the above data.
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HOW TO SUPERVISE THE TOTAL
STATION WORK?
63. Note the location and coordinates of station
point and back sight so that specified
intermediate points can be checked at later
date.
Obtain a soft copy of field work raw data
from the survey agency so that the results can
be checked at any time.
Obtain more number of points to get an
average.
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64. All reflectors and holders are to be cleaned.
Cotton swap dipped in Alcohol should be used on the glass
surfaces.
Tribarchs are to be cleaned and dusted daily.
Dust from all instruments should be removed by a fine brush.
If any instrument is exposed to moisture, it should be throughly
dried and kept in an open case.
The data collector is to be downloaded to the computer. 1/7/2021
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General equipment maintenance
65. All files generated from the download are to be backed
up and checked for the integrity of the backup files
before erasing the field data from the data collector.
Batteries are to be cleaned and to be connected to the
charger.
Generally 14 to 20 hrs are needed to charge the
batteries.
Hence one set of batteries may have to be charged while
a second set is in operation.
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66. Focusing directly at the sun, can result - loss of eyesight
on the spot. Use a filter when observing the sun.
Never remove the hand grip carelessly. If the grip is
loosely or incompletely attached, the instrument could
fall and may cause a serious injury.
Make sure not to short the battery terminals. If these
are shorted, the resulting high current would not only
damage to the battery, but also start a fire.
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67. If the instrument or battery comes in contact
with water, wipe it off as quickly as possible
and set it in a dry place for a while. When it is
completely dry, put it back in the case.
Never disassemble the instrument, if you find
a problem. Contact the dealer.
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