surveying by using digital theodolite

SURVEYING LAB 2012-13 THEODOLITE EXP. (7)

Al-Mansur University Collage– Civil Engineering Department – 2nd

Class of 26

Experiment No.7- 2nd Semester

http://ae.southinstrument.com

Surveying by using Digital Theodolite South ET-05 Electronic

1 Setup

1.1 Tripod setup

In this section we learn how to set up the tripod and roughly center and level it over a small

positioning mark, such as a divot in a penny glued to the _oor, a nail head, or any other small

_xed object.

a. Place the tripod over the positioning mark, setting the legs at a convenient height, and

roughly center and level the tripod head by eye.

b. Suspend the plumb bob included in the theodolite box from the hanger beneath the tripod

head.

c. Readjust the tripod to center the plumb bob over the positioning mark by moving all three

tripod feet by the same amount in the same direction.

d. Firmly _x the tripod feet in position. If necessary, adjust the heights of the tripod legs to

re-center the tripod within 1 cm of the reference mark.

e. Tighten the leg clamps on the tripod.

1.2 Theodolite setup

In this section we learn how to unpack, set up, center, and

level the theodolite.

1.2.1 Seating and centering the theodolite

a) Examine how the tripod is seated in its box. See Fig. 1.

b) Lift the theodolite out of its box by the handle never by

the telescope.

Instrument weight 5.2 kg

Working Temperature -20°～+45°

Working hours 8h

Magnification 30X

Angle measurement 1″or 5″，optional

A theodolite is a telescope mounted to very sensitive

horizontal and vertical protractors. It is capable of measuring

angles and, when used in conjunction with graduated

reference objects, distances with a high degree of accuracy.

Figure 1: Theodolite-in-a-box.

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a) Place the theodolite on the tripod head and screw in the centering screw while holding onto

the handle. Leave the centering screw just loose enough that the theodolite can still slide

around the tripod head.

b) Looking through the optical plummet, focus the centering index mark. Slide the theodolite

on the tripod head until the reference mark is centered in the optical plummet.

c) Fully tighten the centering screw. Look through the optical plummet again and adjust the

theodolite foot screws for _ne alignment with the reference mark.

1.2.2 Leveling the theodolite

A. Referring to Fig. 2, roughly level the instrument using the circular level:

1. Turn the leveling screws A and B in opposite directions to center the bubble along the

AB axis.

2. Turn leveling screw C to bring the bubble to the center of the circular level.

B. Referring to Fig. 3, precisely level the instrument using the plate level.

1. Free the horizontal motion clamp and rotate the instrument horizontally until the plate

level is parallel with line AB.

2. Bring the bubble to the center of the plate level by turning screws A and B in opposite

directions.

3. Rotate the instrument by 90◦ around its vertical axis and turn screw C to center the bubble

once more.

4. Repeat procedures i. and ii. for each 90◦ rotation of the instrument and check that the

bubble is correctly centered for all four points. If after 180◦ of rotation, the bubble is of

center, remove half the error in the bubble centering. Check that when you have swung

another 180◦ back to the initial point, the bubble offset is the same as t he offset you

allowed to remain in the 180◦ rotated position.

Once the theodolite is leveled, double check the optical plummet to make sure that it is still

centered. If not, repeat the procedure in section 1.2.1 (d) through all of section 1.2.2.

2 Measurements

In this section we learn how to take accurate readings of horizontal and vertical angles using a

theodolite.

Figure 2: Diagram for rough leveling with the circular level.

Leveling screw C

Leveling screw A Leveling screw B

Leveling screw A

Leveling screw B

Leveling screw C

Figure 3: Diagram for _ne leveling with the plate level.



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f. Determine how many reference points you will need to measure, and make sure that their

horizontal and vertical positions are clearly marked. In order of measurement, these

reference points will be referred to as X, Y and Z in these instructions.

g. Turn on the theodolite by pressing the green power key.

2.1 Horizontal measurement

To avoid confusion, all horizontal angle measurements should be completed before taking

vertical angle measurements.

(a) Take face-left angle measurements.

1. Rotate the telescope about the turning axis until the instrument is in face-left position.

2. Press the OSET key and rotate the telescope horizontally to give a reading between 0◦

and 1◦.

3. Press HOLD to lock this value.

4. After making sure no one is in the telescope line of sight, press the laser on button on

top of the telescope. Free the horizontal and vertical clamps and swing the laser spot to

reference point X.3

5. Roughly align the laser spot and focus it using the focusing ring on the telescope.

Tighten the horizontal and vertical clamps. Turn o_ the laser.

6. Place a blank sheet of paper in front of the telescope, and, looking through the

telescope, focus the crosshairs using the eyepiece.

7. Remove the paper and focus the telescope on the reference object using the focusing

ring.

8. Check for parallax by moving your head up and down and left to right. If the crosshairs

move, refocus the crosshairs, and refocus the reference object as described above.

9. Looking through the telescope, home in on the reference object using the slow-motion

screws. For horizontal angle measurements, the vertical crosshair must be perfectly

aligned with the reference point, but the horizontal crosshair need not be, as long as

approximately the same part of the vertical crosshair is used for each horizontal

measurement.

10. Check the telescope pointing, book the horizontal angle reading, and check the booking.

11. Release the HOLD key (only applies to the very first reading).

12. Repeat steps 4 to 10 for reference points Y, Z, etc.

(b) Take face-right angle measurements to complete a round of angles.

1. Rotate the telescope about the turning axis until the instrument is in face-right position.

2. Repeat steps (a) 4 - 10 in the face-right position. Now you've booked a series of angles

between 0◦ and 360◦ and a series between 360◦ and 720◦. This completes a round of

angles.

(c) Take at least one more round of angles using an initial horizontal reading between 90◦ and 91◦

for the second round, 180◦ and 181◦ for the third round, etc. If you take only two rounds of

angles, make sure that the readings agree within twice the precision of the theodolite.

(d) Once the desired precision is achieved, take the mean value of the measured angles.

2.2 Vertical measurement

The vertical angle scale is referenced absolutely to the ground, so it is impossible to use

different initial readings for the multiple rounds of angles.

(a) Take face-left angle measurements.

1. Rotate the telescope about the turning axis until the instrument is in face-left position.



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2. After making sure no one is in the telescope line of sight, press the laser on button on top

of the telescope. Free the horizontal and vertical clamps and swing the laser spot to

reference point X.

3. Roughly align the laser spot and focus it using the focusing ring on the telescope.

Tighten the horizontal and vertical clamps. Turn o_ the laser.

4. Place a blank sheet of paper in front of the telescope, and, looking through the telescope,

focus the crosshairs using the eyepiece.

5. Remove the paper and focus the telescope on the reference object using the focusing

ring.

6. Check for parallax by moving your head up and down and left to right. If the crosshairs

move, refocus the crosshairs, and refocus the reference object as described above.

7. Looking through the telescope, home in on the reference object using the slow-motion

screws. For vertical angle measurements, the horizontal crosshair must be perfectly

aligned with the reference point, but the vertical crosshair need not be, as long as

approximately the same part of the horizontal crosshair is used for each vertical

measurement.

8. Check the telescope pointing, book the vertical angle reading, and check the booking.

9. Repeat steps ii. to viii. for reference points Y, Z, etc.

(b) Take face-right angle measurements to complete a round of angles.

1. Rotate the telescope about the turning axis until the instrument is in face-right position.

2. Repeat steps (a) ii. - ix. in the face-right position. This completes a round of angles.

(c) Take at least one more round of angles. If you take only two rounds of angles, make sure that the

readings agree within twice the precision of the theodolite.

(d) Once desired precision is achieved, take the mean value of the angles measured.

3 Packing up

1. Open the theodolite box.

2. Turn o_ the theodolite.

3. Align the theodolite as it was before packing. Refer to Fig. 1.

4. Bring the theodolite foot screws to the center of their travel.

5. Holding the theodolite handle with one hand, undo the centering screw with the

other.

6. Put the theodolite back in the box in its original position and close the clasps. Refer

to Fig. 1.

7. Being careful not to disturb the positioning mark, lift the tripod away, collapse it,

and put it away.



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4 Glossary of terms

Gradient - An alternative to measuring vertical angles in degrees, the gradient is defending as

the tangent of the vertical angle with respect to the horizontal times 100%. For example, a

gradient of -50% means a slope of 22:5◦ below the horizontal.

Face left - The theodolite position in which the vertical circle is on the viewer's left while he

looks into the telescope.

Face right - The theodolite position in which the vertical circle is on the viewer's right while

he looks into the telescope.

Horizontal circle - The graduated circle in the horizontal plane that the theodolite reads out

to measure horizontal angles.

Horizontal clamp - Thumbscrew that can be used to _x the angle of the theodolite with

respect to the

Vertical axis. When the horizontal clamp is tight, the instrument can be translated

horizontally with the slow-motion screw.

Line of collimation - The line of sight through the center of the telescope crosshairs.

Optical plummet - Small telescope whose eyepiece is near the bottom of the theodolite that

looks at the directly beneath the theodolite and is used for centering.

Round of angles - A complete set of angle measurements performed _rst in the face-left, then

in the face-right position.

Slow-motion screw - The _ne adjustment screw used to translate the theodolite in the

horizontal or vertical plane when the horizontal or vertical clamp is tightened.

Tangent screw - See slow-motion screw.

Trunnion axis - The axis about which the telescope pivots.

Vertical axis - The axis about which the horizontal circle pivots.

Vertical circle - The graduated circle in the vertical plane that the theodolite reads out to

measure vertical angles.



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Accessories

Digital LCD monitor

The Keys



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Battery

Laser theodolite



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6. BASIC SURVEY 6.1 Observation from Normal/Reversed Position ―Normal position telescope‖ means that the shaft disc is on the left side of the

telescope when observers face eyepiece lens (see figure). ―Reversed position

telescope‖ means that the shaft disc is on the right side of the telescope when

observers face eyepiece lens. In angle measuring, we should get the measuring result

through averaging the two values got from both observations above. And only in this

way can the influence caused

by the instrument’s

systematic errors be

eliminated effectively.

Therefore, when doing

horizontal and vertical

observation, rotate telescope

180°to do normal position

observation after finishing

reversed position observation



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6.2 Horizontal Angle “0” Setting (0 SET)



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6.7 Measure Zenith Distance and Vertical Angle

1. (1)Zenith distance: If vertical angle is 0°in zenith direction, then the vertical

angle measured in this way is the zenith distance. (shown as the figure) Zenith

distance =（L+360°－R）/2 Index difference =（L+R－360°）/2

2. (2)Vertical angle: If vertical angle is 0° in horizontal direction, then the vertical

angle measured in this way is the perpendicular angle.(See the figure).

3. Vertical angle =（L±180°－R）/2 Index difference =（L+R－）/2



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6.10 Output Angle

Turn on and enter angle measure mode,

and press FUNC key to enter the second

function selection mode. Press OUT key

to transmit the current angle to serial-port

or electronic controller (baud rate is

1200), ―-------‖ will be displayed on the

screen for one second after successful

transmission.

6.11 Save Angle

Turn on and enter angle measure mode,

press FUNC key to enter the second

function selection mode, and then press

REC to save angle. At that time, the

current angle glitters twice, which represents it has been saved to the memory. If you

want to save angle again, press REC key after regulating an angle.

If you want to review saved angle data, please refer to Chapter 7 about memory.

Notice: the instrument only supplies 256 groups of angle data (each group of angle

data includes one vertical angle and one horizontal angle). If angle data saved

exceeds256 groups, ―FULL‖ will be displayed on the interface which means that

memory is full.

Users then need to clear manually to resave angle, please refer to the chapter about

memory for more details.

6.12 Measure Distance with Stadia

The distance from the measuring object to the instrument can be obtained by using

the stadia hair of the telescope with the accuracy ≤0.4%D.

Set up the instrument at point A and put the surveying rod on target point B.

Read the intercept d of apparent lines from up and down from the reticle on the

survey rod.

The horizontal distance (D) between A and B can be calculated with the formula

below: L= 100× l



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7. 5 Data Download from New ET (Sample with Access port)

Step:

1. Connect series port on ET with the CE-203U to the series port or USB of PC.

2. If connect PC with USB port, pleas install the drive firstly.

Open the file like ‗Scomassistant‘ or ‗AccessPort‘ （example:



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10. SPECIFICATIONS Telescope

Image Erect image

Magnification 30X

Effective aperture 45mm

Resolution 3″

Field of view 1°30′

Shortest stadia 1.4m

Stadia multiplication constant 100

Stadia additive constant 0

Stadia precision ≤0.40%L

Tube length 157mm

Angle measurement

Angle measurement mode Absolute encoding mode

Diameter of raster disks (vertical and horizontal) 79mm

Minimum display reading 1″or 5″，optional

Detection mode Horizontal angle: dual

Vertical angle : dual

Angle measurement Unit 360°/ 400gon/6400mil,optional

Precision ET-02: 2″， ET –05: 5″

Leveling vials

Plate vial 30″/2mm

Circular vial 8′/2mm

Vertical compensator（05B mode without this item）

System liquid condenser mode, optional

Working range ±3′

Precision ±3″

Optical plummet

Image Erect image

Magnification 3X

Focusing range 0.5～∝

Field of view 5°

Display

Type LCD, double lines, line segment

Data input/output

Interface RS --232C

On-board battery

Power source Rechargeable NI-H Battery

Voltage DC 4.8V

Continuous working hours 8h

Working environment



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surveying by using digital theodolite

Documents

tripod head

theodolite box

tripod setup

theodolite setup

tripod legs

tripod feet

plate level

theodolite foot screws