How to Check Total Station Accuracy Before Field Work – Daily Verification Checklist Malaysia

A total station may have a valid calibration record and still deserve a quick verification before important fieldwork.

Why?

Because many things can happen between calibration and the next survey:

• Transportation

• Vibration inside a vehicle

• Accidental impact

• Tripod problems

• Tribrach movement

• Incorrect prism settings

• Operator setup error

A practical pre-field check helps answer an important question:

“Is the total station behaving normally before we start using it for important measurements?”

This does not replace formal calibration.

It is a field verification routine designed to detect obvious problems before they affect a day's survey work.

Calibration vs Daily Field Check

These are different activities.

Calibration

Calibration evaluates measurement performance using suitable references, procedures and equipment.

Field Check

A field check is a practical verification performed by the survey team to identify abnormal behaviour.

Think of it this way:

Calibration = Formal measurement evaluation

Field Check = Is anything obviously wrong today?

Both can form part of good equipment management.

Why Check a Total Station Before Important Work?

Imagine completing an entire day of setting out.

At the end of the day, you discover:

• Wrong prism constant

• Tribrach was loose

• Plummet was not centred

• Backsight orientation was wrong

Now every point may need to be investigated.

A short check at the beginning of the job can sometimes prevent hours of rework.

1. Inspect the Total Station Physically

Before setting up, look at the instrument.

Check for:

• Cracked housing

• Loose parts

• Impact marks

• Damaged objective lens

• Moisture

• Missing covers

• Damaged battery

Ask the survey team:

“Did anything happen to this instrument since it was last used?”

A drop or impact should not be ignored simply because the total station still switches on.

2. Inspect the Tripod

A total station depends on its support system.

Check:

• Tripod legs

• Leg clamps

• Tripod head

• Mounting screw

• Feet

The tripod should remain stable when loaded.

An unstable tripod can create measurement problems even when the total station itself is correctly calibrated.

3. Check the Tribrach

Inspect:

• Levelling screws

• Locking mechanism

• Base

• Mechanical play

Make sure the total station is correctly secured to the tribrach.

If the instrument can move relative to the tribrach, investigate before surveying.

4. Set Up Over a Stable Point

Choose a stable survey point.

Avoid setting tripod feet on:

• Loose soil

• Unstable fill

• Soft mud

• Moving platforms

Be careful with hot or soft asphalt.

A setup that slowly sinks can cause the total station to go out of level during work.

5. Check Centering

Use the instrument's:

• Optical plummet

or:

• Laser plummet

depending on the model.

Centre the total station accurately over the station point.

After levelling, recheck centering.

Levelling adjustments can slightly change the position if the initial setup is poor.

6. Check Levelling

Perform rough and fine levelling according to the instrument procedure.

Then rotate the total station.

Observe whether the level indication remains reasonably consistent.

If the instrument is level in one direction but shows a large repeatable change after rotation, investigate before starting critical work.

7. Check the Electronic Level

For total stations with an electronic level, observe the indication while rotating the instrument.

Watch for:

• Unexpected large changes

• Repeated tilt warnings

• Unstable indication

Do not assume every tilt warning means the compensator is defective.

Possible causes also include:

• Tripod movement

• Tribrach problem

• Poor setup

• Unstable ground

8. Check the Compensator

A properly levelled instrument should normally operate without repeated compensator errors when within its specified operating conditions.

If you repeatedly see:

• Tilt error

• Compensator error

• Out-of-range warning

stop and investigate.

Turning off the compensator simply to remove the warning is not a proper solution.

9. Check the Optical or Laser Plummet

A useful check is to observe the centering point while rotating the instrument according to an appropriate procedure.

For example, observations may be made around:

• 0°

• 90°

• 180°

• 270°

• Back to 360°

The indicated centre should behave consistently within the applicable checking criteria.

If the laser or optical plummet appears to move significantly around the ground point during rotation, inspection or adjustment may be needed.

10. Check Telescope Focus

Aim at a clear target.

Adjust:

• Eyepiece

• Telescope focus

The crosshair and target should both appear sharp.

Then check for parallax.

What Is Parallax?

Parallax occurs when the target image and crosshair are not correctly focused in the same apparent plane.

A simple practical check is to move your eye slightly while looking through the telescope.

If the crosshair appears to move relative to the target, focusing needs attention.

Parallax can cause aiming error.

11. Check the Crosshair

Observe whether the crosshair appears:

• Sharp

• Stable

• Normal in orientation

If the crosshair looks tilted or the aiming behaviour has changed after impact, further inspection may be appropriate.

12. Check Horizontal Movement

Rotate the instrument horizontally.

Check for:

• Smooth movement

• Abnormal resistance

• Excessive play

• Strange noise

Then test:

• Horizontal clamp

• Horizontal tangent screw

Fine adjustment should be controlled.

13. Check Vertical Movement

Move the telescope vertically.

Test:

• Vertical clamp

• Vertical tangent screw

Look for:

• Stiffness

• Free play

• Jerky movement

• Telescope drift

Mechanical abnormalities should be addressed before they worsen.

14. Check Horizontal Angle Repeatability

Aim carefully at a stable, well-defined target.

Repeat the observation.

The readings should behave consistently with the instrument's specification and the quality of the field setup.

For more meaningful checks, appropriate Face I and Face II observations can be used.

Why Face I and Face II Observations Matter

Observing the same target in both telescope faces can help reveal certain angular/alignment issues.

This is useful as a field diagnostic technique.

However:

Face I / Face II checking is not a complete total station calibration.

If the results show abnormal discrepancies, professional evaluation may be required.

15. Check Vertical Angle

Observe a stable target using an appropriate procedure.

If vertical-angle results appear abnormal, first confirm:

• Instrument is correctly levelled

• Target is stable

• Telescope is correctly aimed

• Compensator is operating normally

Persistent abnormalities may indicate the need for adjustment or calibration.

16. Check EDM Distance

Use a stable prism at a suitable test distance.

Make sure:

• Correct prism mode is selected

• Correct prism constant is entered

• Prism is clean

• Prism pole is stable

Measure the target several times.

Look for consistent behaviour.

Repeatability Is Not Accuracy

Suppose the total station repeatedly measures:

50.030 m

The repeated result may look excellent.

But if the true/reference distance is:

50.000 m

there is still a problem.

Therefore:

Repeatability tells you about consistency.

Accuracy requires comparison with an appropriate reference.

This distinction is important.

17. Check the Prism Constant

Before EDM work, verify the prism setting.

Common prism constants can include values such as:

• 0 mm

• -30 mm

• -34 mm

and other manufacturer-specific values.

Do not guess.

Check the actual prism and instrument convention.

A wrong prism constant can create a systematic distance offset.

18. Check Prism Height

Measure and enter the correct prism height.

Do not rely on yesterday's value remaining in the total station.

If:

Actual Prism Height ≠ Entered Prism Height

elevation-related results can be wrong.

19. Check Instrument Height

The same principle applies to instrument height.

Measure it using your project's required method.

Enter the correct value.

A perfectly calibrated total station cannot correct an incorrect instrument-height entry.

20. Check the Prism Pole Bubble

Place the prism pole in a suitable position and inspect its bubble.

A pole can appear vertical according to a misadjusted bubble while physically leaning.

This can cause horizontal positioning errors.

For accurate setting out, the prism pole is part of the measurement system.

21. Check the Backsight

This is one of the most important pre-survey checks.

Confirm:

• Correct backsight point

• Correct coordinates

• Correct target

• Correct prism height where relevant

• Correct orientation

A wrong backsight can rotate an entire survey.

22. Measure the Backsight Again

After establishing orientation, measure the backsight or another known control point as appropriate.

Compare the result with the expected value.

This provides a useful confirmation that the setup has not been incorrectly configured.

23. Check Another Known Control Point

Where suitable control is available, measure an independent known point.

This can help detect:

• Wrong station

• Wrong backsight

• Coordinate entry error

• Orientation problem

• Measurement abnormality

Independent verification is stronger than relying only on the point used to establish orientation.

Example – Control Point Check

Suppose the known point is:

E = 5,250.000 m

N = 8,130.000 m

You measure it and obtain a significantly different position.

Do not immediately adjust the total station.

First investigate:

• Station coordinates

• Backsight

• Centering

• Levelling

• Prism height

• Prism constant

• Control-point identification

Only after field setup errors have been eliminated should instrument accuracy become the primary suspect.

24. Check Reflectorless Mode Separately

If you will use reflectorless EDM during the project, test it separately.

Prism and reflectorless measurement are not identical operating modes.

An instrument can potentially have:

• Normal prism measurement

• Abnormal reflectorless measurement

or the opposite.

Test the function you actually intend to use.

25. Check Battery Condition

A weak battery can cause field interruptions.

Before leaving for an important project, confirm:

• Main battery charged

• Spare battery available where required

• Charger working

• Contacts clean

Do not wait until the total station shuts down in the middle of a critical setting-out operation.

26. Check Display and Keypad

Test the controls required for the job.

Look for:

• Missing LCD segments

• Dim display

• Unresponsive buttons

• Intermittent keypad

If your total station has dual displays, check both sides.

27. Check Data Storage

Before collecting hundreds of points:

• Confirm correct job

• Check available memory

• Save a test point

• Verify point information

This is particularly important for topographic and as-built work.

28. Check Data Transfer Before a Major Survey

If the job depends on downloading data afterwards, verify the communication workflow before fieldwork.

Confirm:

• Cable

• USB

• Bluetooth

• Software

• File format

A total station full of survey data is not useful if the team cannot retrieve it when the project deadline arrives.

29. Check Coordinate System and Units

For coordinate-based projects, verify:

• Coordinate system

• Local grid

• Units

• Project datum where applicable

When combining total station and GNSS data, this becomes particularly important.

A coordinate-system mismatch can appear to be an instrument accuracy problem.

Pre-Field Total Station Checklist

Before important survey work:

□ Instrument physically inspected

□ Tripod stable

□ Tribrach checked

□ Centering verified

□ Levelling verified

□ Plummet checked

□ Compensator normal

□ Telescope clear

□ Parallax eliminated

□ Horizontal movement normal

□ Vertical movement normal

□ Angle observations reasonable

□ EDM checked

□ Prism constant correct

□ Prism height correct

□ Instrument height correct

□ Prism pole bubble checked

□ Backsight confirmed

□ Known control verified

□ Battery charged

□ Data storage working

This can become part of the survey team's standard operating procedure.

When Should You Stop Work?

Do not simply continue collecting points if you discover unexplained problems such as:

• Large control-point discrepancy

• Repeated angle inconsistency

• Distance discrepancy

• Total station repeatedly going out of level

• Compensator error

• Plummet movement

• Unstable EDM

• Mechanical movement

• Abnormal behaviour after a drop

Investigate the cause first.

It is usually better to lose a short period checking the instrument than to discover later that an entire day's measurements are questionable.

Daily Check Does Not Replace Calibration

A field check can tell you:

“The instrument appears to behave normally against today's checks.”

It does not provide the same evidence as formal calibration.

For professional equipment management, combine:

Daily / Pre-Field Verification

Known Control Checks

Preventive Maintenance

Scheduled Calibration

Additional Inspection After Abnormal Events

This creates a much stronger measurement-quality system.

Total Station Accuracy Check & Calibration Malaysia

MTM Precision provides total station inspection, calibration, servicing and repair in Malaysia.

If your field verification identifies a problem, MTM Precision can investigate issues involving:

• Horizontal angle

• Vertical angle

• EDM

• Compensator

• Telescope/collimation

• Optical or laser plummet

• Levelling

• Tribrach

• Mechanical movement

• Drop damage

Service support includes surveying instruments from brands commonly used in Malaysia such as Topcon, Nikon, Leica, Trimble and Pentax, subject to model, condition, service requirements and parts availability.

When sending an instrument with an accuracy complaint, provide the actual symptom.

For example:

“Our known control point differs by approximately 15 mm.”

is much more useful than:

“Total station not accurate.”

If possible, also provide:

Brand + Model + Test Distance + Prism Type + Prism Constant + Measurement Results

This helps separate:

Setup Error

from:

Accessory Error

from:

Instrument Error.

Contact MTM Precision

MTM Precision Sdn. Bhd.
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia

🌐 Website: www.mtmpre.com.my
📧 Email: mtmpre@yahoo.com
📱 WhatsApp: +6016-660 7346