Study of Instruments of Total Station In Engineering Surveying

INTRODUCTION

General:

Total station is a combination of Electronic Theodolite and Electronic Distance Meter (EDM) in one unit. This instrument directly measures 3D co-ordinates, slope, horizontal and vertical distances. This has large internal memory of 3000 points to store field data and can be directly down loaded to the computer from the instrument through interface cable.

Electronic Distance Meter:

This is used to measure directly, to an acceptable accuracy, the distance between any two inter – visible points in the survey system. The technique of EDM eliminates the need for chaining or taping.

Principle of EDM:

The basic principle is the indirect determination of the time required for a light beam to travel between two stations and by using frequency the distance is displayed.

Basic Functions of EDM:

  1. It generates the carrier and measuring wave frequencies.
  2. It modulates and demodulates the carrier wave.
  3. It measures the phase difference between the transmitted and received waves.
  4. It displays the result of measurement.

LEVELING THE TOTAL STATION

  • Leveling the Total Station must be accomplished to sufficient accuracy otherwise the instrument will not report results.
  • Leveling the instrument takes 30 to 45 minutes and make sure you can see all targets from the instrument station before going through the process

Step 1: Tripod Setup

  • Tripod legs should be equally spaced
  • Tripod head should be approximately level
  • Head should be directly over survey point

Step 2: Mount Instrument on Tripod

  • Place Instrument on Tripod
  • Secure with centering screw while bracing the instrument with the other hand
  • Insert battery in instrument before levelling

Step 3: Plumb

  • Turn on the instrument. The laser plummet will be activated automatically, and the Level/Plummet screen appears.
  • IF NECESSARY Move the position of the tripod legs to make large
    adjustments to center the plummet over the ground point.
  • Use the footscrews to make small adjustments to center the plummet over the ground point.

Step 4: Rough Leveling

  • Adjust the height of the tripod legs to level the circular level bubble. Note: Do not move the legs from their position just lengthen or shorten them, one at a time, as necessary to bring the bubble into centre.

Step 5: Fine Plumb & Level:

  • At this time your instrument should be very close to level and very close to the ground point, check the plummet & circular level bubble to verify this. If this is not the case you must repeat the Plumb & Rough Leveling steps above, otherwise, continue on to the next step.
  • Turn the instrument until it is parallel to two footscrews.
  • Centre the electronic level of the first axis by turning the two footscrews. Arrows show the direction of rotation required. When the electronic level is cantered the arrows are replaced by checkmarks.
  • Centre the electronic level for the second axis by turning the last footscrew. An arrow shows the direction of rotation required. When the electronic level is cantered the arrow is replaced by a checkmark.
  • When the electronic level is cantered and three checkmarks are shown, the instrument has been perfectly leveled up.
  • IF REQUIRED, Centre the instrument precisely over the ground point. Loosen the instrument from the tripod (loosen only) and slide the instrument over the point while sighting.

DISPLAY AND OPERATION KEYS

 

Key Description
[POWER] ON/OFF of power supply.
[ESC] Returns to previous screen or cancels an operation.
[ILLU] Turns the illumination of the LCD display and telescope reticle on and off.
[ENT] Accepts the selected (highlighted) choice or the displayed screen value.
[LASER] Displays the laser plummet and the LD point screen when you push the Laser key.

(Refer to “2.5 LD POINT, Laser pointer”, “3.2 Laser plummet”).

[Alphanumeric] At the numerical value screen, the numerical value and the sign “.” displayed are input. The English characters printed right under numeric of each key are input.
[HELP] Pressing [ILLU]+[ESC] key causes a help menu to appear in MODE A or MODE B or causes a help message to appear.

 

Function keys

Display

MODE A

F. Key Description
[MEAS] F1 Pressing this key one time measures the distance in normal mode. Another measurement type can be selected by Initial Setting 2.

Pressing this key twice measures the distance in coarse mode. Another measurement type can be selected by initial setting 2.

[TARGET] F2 Switches the target. REFLECTORLESS / SHEET / PRISM
[0 SET] F3 Resets the horizontal angle to 0° 0’ 0” by pressing twice.
[S.FUNC] F4 Linertec Express Special Functions.
[MODE] F5 Switches the screen between MODE A and MODE B.
MODE B
[DISP]

 

F1 Switches the display composition in the order “H.angle/H.dst./V.dst.”, “H.angle/V.angle/S.dst.” and “H.angle/V.angle/H.dst./S.dst./V.dst.”
[ANG SET] F2 Brings up the angle setting screen for setting angle-related

parameters.

(H.ANGLE /%GRADE, H.ANGLE INPUT and L/R REVERSE)

[HOLD] F3 Pressing this key twice retains (holds) the horizontal angle shown on the display.
[CORR] F4 Brings up the screen for changing the target constant, temperature, pressure setting.
[MODE] F5 Switches the screen between MODE A and MODE B.

[Other functions]

[ ] F1 Moves the cursor to the left.
[ ] F2 Moves the cursor to the right.
[ ] F3 Moves the cursor up.
[ ] F4 Moves the cursor down.
[ △ ] F1 Goes back five items on the screen.
[ ▽ ] F2 Gose forward five items on the screen.
[RETICLE] F3 Changing the reticle illumination when pressing illumination key.
[LCD] F4 Changing the LCD contrast when pressing illumination key.
[ILLU] F5 Changing the LCD illumination when pressing illumination key.
[CLEAR] F5 Clear the figure.
[SELECT] F5 Open the selection window.

[How to move the menu number]

Example:

The cursor is located at Menu 1.

Press the numeric key 0 and 2 to move to Menu 2 or press [F4] [ ].

  • Alphanumeric input

The point name is input by the alphanumeric keys as following.

Key Letter under key Letter & figure order to input
[0] [@][.][_][-][:][/][0]
[1] PQRS [P][Q][R][S][p][q][r][s][1]
[2] TUV [T][U][V][t][u][v][2]
[3] WXYZ [W][X][Y][Z][w][x][y][z][3]
[4] GHI [G][H][I][g][h][i][4]
[5] JKL [J][K][L][j][k][l][5]
[6] MNO [M][N][O][m][n][o][6]
[7] [ ][?][!][_][¯][^][|][&][7]
[8] ABC [A][B][C][a][b][c][8]
[9] DEF [D][E][F][d][e][f][9]
[.] [.][,][:][;][#][(][)]
[+/-] [+][-][*][/][%][=][<][>]

 

  • LD POINT, Laser pointer

The Laser pointer function turns the laser beam on continuously to become the aiming point so that visual confirmation is possible.

  1. When the [F2] [ RED MARK] key is pressed after pressing the [Laser] key, the Laser pointer function is turned on. The Laser indicator is turned on and the “ ” mark on the left of the screen blinks while the Laser pointer function is operating.
  2. If the [Laser] key is pressed and the [F2] [RED MARK] key is pressed while the Laser

pointer function is operating, the Laser pointer function is turned off.

    1. The beam of the sun is strong and visual confirmation is difficult in daytime when outdoors.
    2. The laser beam is designed not to be able to observe through the telescope.
    3. Please visually align the laser beam to the target and mark the centre.

Confirm the alignment (horizontal and vertical ) before measuring when performing accurate work like stake out when using the Laser pointer function.

Also refer to “11.9 The EDM beam axis”.

    1. Please do not look at the laser source of beam directly.

4. TARGET SETTING

The target mode and its Constant of current setting are shown at the left of the battery mark. For example in case of each Constant 0, Reflector less (Non-Prism); N 0, Prism; P 0

Pressing [F2] [TARGET] changes the target mode.

  • The target mode is changed sequentially as follows. Reflector sheet – Prism – Reflectorless
  • The selected target mode is stored in the memory even if the power is turned off. So, next time you can use the same mode after turning on.
  • The target Constant differs according to the selected target mode. So, confirm the target mode and its Constant shown at the top screen after changing the target.

[Distance measurement by reflectorless (Non-Prism) mode]

  • The measurement range and accuracy of Reflectorless are based on the condition that laser beam is emitted perpendicular to the white side of the Kodak Gray Card. The measurement range may be influenced by the shape of the target and its environment. There is a possibility that the range may vary when the target does not satisfy the conditions above at survey work.
  • Pay attention to the following in case of distance measurement by Reflectorless. In case of resulting in low accuracy, perform the distance measurement by Prism.
  • The CODE number 521 [LONG RANGE MES.] shows ON/OFF.
  • The WARNING (Laser Power) screen is displayed when Message ON is selected, and then [F1] [MEAS] key is pressed.
  • Pressing [F1] [MEAS] one time selects “Second MEAS setting” and twice selects “QUIT”.

① There is a possibility that correct distance measurement may be impossible by dispersion or reduction of laser beam when the laser beam comes into the target from diagonal angle.

② There is a possibility that the instrument cannot calculate correctly when receiving

reflected laser beam from forth and back directions in case of measuring the target on the road.

③ There is a possibility that synthesized values are calculated and the distance may become

longer or shorter than the actual one when the operator measures the target of slope or sphere or rugged shape.

④ There is a possibility that the instrument cannot calculate correctly collecting the reflected

laser beam from a man or a car that comes and goes in front of the target.

[Distance measurement by reflector sheet mode]

Position the Reflector sheet whose reflecting surface faces the aiming line to be approx. right angle when the distance is measured by it. If it is positioned not to be approx.

right angle, there is a possibility that correct distance measurement may be impossible by dispersion or reduction of laser beam.

[Applied measurement range by each target mode]

  • When a wrong target mode is selected, a correct distance cannot be measured. Please select a correct target mode and measure.
  • It is sometimes possible to measure without prism under special conditions like in the close distance, targeting on a wall surface. However, there is a possibility including some errors in this case, so be sure to select the reflectorless mode.
  • The target constant should be correctly selected and confirmed in case that the reflector sheet is used at the prism mode and the prism is used at the reflector sheet mode.
  1. ANGLE MEASUREMENT
  • Measuring an angle

Aim at the first target, then press [F3] [0 SET] twice in succession to reset the horizontal angle to 0.

Aim at the second target, then read the horizontal angle and vertical angle.

NOTE

  • The [F3] [0 SET] key cannot reset the vertical angle to 0.
  • Even though you turn the power off during a survey, the horizontal angle displayed last time is saved, so that it is restored when the power is turned on next time.
  • When the restored horizontal angle is not necessary, reset it to 0.

—————————————————————————————————————————————

  • Resetting the horizontal angle to 0

Pressing [F3] [0 SET] twice in succession resets the horizontal angle to 0° 0′ 0″.

NOTE

  • The [F3] [0 SET] cannot reset the vertical angle to 0.
  • Pressing the [F3] [0 SET] accidentally during measurement does not reset the horizontal angle to 0 unless you press it again. Once the buzzer stops sounding, you can go to the next step.
  • You can reset the horizontal angle to 0 any time except when it has been held.

————————————————————————————————————————————-

Distance measurement

The LTS-200 series has two distance measurement modes of primary MEAS and second MEAS. Pressing the [F1] [MEAS] one time goes to primary MEAS and twice goes to second MEAS.

You can freely select and allocate your desired measurement mode in primary MEAS and second MEAS by the initial setting 2. The “MEASURE SHOT” is set at primary MEAS and “TRACK CONT” is set at second MEAS as a factory default setting.

  • MEASURE SHOT means the distance measurement by the shot mode.
  • MEASURE CONT means the distance measurement by the continuous mode.
  • TRACK SHOT means the fast distance measurement by the shot mode.
  • TRACK CONT means the fast distance measurement by the continuous mode. Confirm the target constant before beginning the distance measurement.

Example: “MEASURE SHOT”at primary MEAS (Factory default setting)

Collimate the telescope at a target and press the [F1] [MEAS] once to start measuring the distance. Once distance measurement has been started, the distance measurement mark remains displayed. Upon reception of a reflected light from the target, the instrument beeps and displays the mark to start the shot measurement automatically.

  • Pressing the [F1] [MEAS] after collimating the telescope at the prism starts shot distance measurement with the “MEAS” text blinking. Distance measurement is completed and the “MEAS” text stops blinking the moment the distance measured by shot measurement is displayed. During continuous measurement, the “MEAS” text keeps on blinking. Pressing

the [F1] [MEAS] again terminates both distance measurement and blinking of the “MEAS” text.

  • Pressing[F5][MODE]and [F1] [DISP] cycles through the sets of display items:“H.angle/H.dst./V.dst.”, “H.angle/V.angle/S.dst.”, and “H.angle/V.angle/H.dst./S.dst./V.dst.”
  • Pressing the [ESC] or [F2] [TARGET] or [F5] [MODE] during distance measurement stops it.
  • If the shot count for distance measurement has been set to 2 or more in “initial setting 2”, the distance is measured for the specified number of times to display the averaged value.

Example: “TRACK CONT” at second MEAS (Factory default setting)

Collimate the telescope at a Target and press [F1] [MEAS] twice to start measuring the distance. Upon reception of a reflected light from the target, the instrument beeps and displays the mark to start the TRACK distance measurement.

  • Press [F1] [MEAS ] twice.
  • Pressing [F1] [MEAS] twice after collimating the telescope at the Target starts Continuous distance measurement at fast speed with the “MEAS” text blinking.

It remains blinking during the measurement. If you press the [F1] [MEAS] again, Distance measurement is completed and the “MEAS” text stops blinking.

  • Pressing [F5][MODE]and[F1] [DISP] cycles through the sets of display tems: “H.angle/H.dst./V.dst.”, “H.angle/V.angle/S.dst.”, and “H.angle/V.angle/H.dst./S.dst./V.dst.”
  • Pressing the [ESC] or [F2] [TARGET] or [F5] [MODE] during fast distance measurement stops it.

 

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