Docstoc

Calibration Testing and Adjustment Of Survey Instruments

Document Sample
Calibration Testing and Adjustment Of Survey Instruments Powered By Docstoc
					                MAIN ROADS
                Western Australia



Survey and Mapping Job Instruction 23/04/04                                     Issue Date 10/97


  CALIBRATION, TESTING AND ADJUSTMENT OF SURVEY
                   INSTRUMENTS




This document is owned and controlled by the Chief Surveyor.

The Quality Co-ordinator (Surveys) is the delegated custodian.

All comments for revision should be submitted to the Quality Co-ordinator (Surveys ).




Authorisation

As Chief Surveyor of Main Roads Western Australia, I authorise the issue and use of
this job instruction..




          .......................................
          CHIEF SURVEYOR

          Date: ___/___/___




                                All Controlled Copies shall be marked as such

MAIN ROADS Western Australia             Calibration, Testing and Adjustment            Page 1 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
REVISION STATUS RECORD

  Page       Latest           Latest                               Revision
   No       Revision         Revision                        Description/Reference
              No               Date
    1
    2             1          19/12/97        Details of this revision
    3
    4
    5
    6
    7
    8
    9
   10
   11
   12
   13
   14
   15             1          19/12/97        Procedure for indexing the barometer in the
                                             Curtin store added.
   16




Authorised by:___________________                                    Date      ______/______/______
               Chief Surveyor




MAIN ROADS Western Australia             Calibration, Testing and Adjustment                    Page 2 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                           23/04/04 - Issue 1 10/97 Rev 1
                                                      CONTENTS



1.             PURPOSE...................................................................................................... 4

2.             SCOPE ........................................................................................................... 4

3.             REFERENCE DOCUMENTS..................................................................... 4

4.             DEFINITIONS .............................................................................................. 4

5.             PROCEDURE ............................................................................................... 5

5.1            Electronic Distance Meters (EDM) and Total Stations ............................. 5

5.2            Optical Theodolites, Electronic Theodolites and Total Stations .............. 6

5.3            Testing and Adjustment of Survey Levels .................................................. 9

5.4            Calibrated Survey Measuring Bands ........................................................ 11

5.5            Third Order Levelling Staves .................................................................... 11

5.6            Tribrachs and Optical Plummets .............................................................. 12

5.7            Minor Survey Equipment .......................................................................... 12

5.8            Specifications for Survey Equipment ....................................................... 14


6.             APPENDICES

Appendix A                        Field Instruction - Curtin Calibration Baseline ............... 15

7.             FORMS

23/04/04/01                       EDM Recording Sheet - Curtin Baseline

23/04/04/02                       Total Station Calibration Checklist

23/04/04/03                       Third Order Staves Calibration Checklist




MAIN ROADS Western Australia             Calibration, Testing and Adjustment                                          Page 3 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
1.        PURPOSE

The purpose of this job instruction is to describe the process to be used for the
calibration, testing and adjustment of survey instruments.


2.        SCOPE

This job instruction shall be used by the Survey and Mapping Branch for the calibration
of survey instruments and by all Survey Crew Leaders to test and adjust survey
instruments and equipment.

Further information can be obtained from the Quality Co-ordinator (Surveys).


3.        REFERENCES

The following documents relate to this procedure:

    Surveying Equipment Procedure 2300/02/07
    Operations Centre Surveying Equipment Procedure 2300/03/08/OP
    Survey and Mapping Specification 2300/05/11 Surveying Equipment
    DOLA Procedure 2000/02/024 Calibration of EDM Equipment
    Handbooks for Various Instruments


4.        DEFINITIONS

The following terms used in this procedure have the specific meanings indicated:

DOLA                         Department of Land Administration
EDM                          Electronic Distance Meter
GSC                          Geodetic Services Co-ordinator
QC(S)                        Quality Co-ordinator (Surveys)
SES(O)                       Senior Engineering Surveyor (Operations)
Authorising Officer          One of : GSC SES(O) QC(S)




MAIN ROADS Western Australia             Calibration, Testing and Adjustment        Page 4 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.        PROCEDURE

5.1       Electronic Distance Meters (EDM) and Total Stations

         Calibration of EDM's and the distance meters on Total Stations shall be arranged
         by the Survey and Mapping Branch.

         The instruments shall be calibrated using the survey baseline at Curtin University,
         Kent Street, Bentley (for Site Location diagram see Appendix A).

         The following procedure shall be undertaken to determine a calibration constant
         for the EDM or Total Station.

5.1.1 Field Survey

         Upon request from the QC(S), the field survey component shall be arranged by
         Data Acquisition staff. The field crew is to use the EDM or Total Station
         Calibration Checklist (form 23/04/04/02), follow the field instructions
         (Appendix A) and record the observation data on form 23/04/04/01.

5.1.2 Processing

         The results of the test shall be processed, preferably by the surveyor who
         completed the field survey, using the DOLA supplied Calibration program.

5.1.3 Certification of Calibration

         The printed certificate produced by the calibration software, shall be signed by the
         officer entering the data, and authorised by the Authorising Officer.

         The original of the Certificate of Calibration shall be passed to the QC(S) with the
         field observation sheet for filing on the appropriate file (15-375-** series : one for
         each Total Station or EDM), and a copy of the Certificate placed in the Instrument
         case.

5.1.4 Calibration Status Tag

         The Authorising Officer shall ensure that the Calibration Status Tag on the
         instrument is updated, after authorisation of the Certificate of Calibration.

5.1.5 Up-date the Calibration Database

         The QC(S) shall arrange for the Calibration database to be up-dated to show the
         completion of the calibration test and the date of the next required test.




MAIN ROADS Western Australia             Calibration, Testing and Adjustment         Page 5 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.2       Optical Theodolites, Electronic Theodolites and Total Stations

          The following procedure shall be undertaken for the testing of horizontal and
          vertical collimation in Optical Theodolites, Electronic Theodolites and Total
          Stations.

          These procedures shall be read in conjunction with the handbook for the
          instrument as the testing procedure and adjustment does vary between different
          makes and types of instruments such as optical or electronic.

5.2.1 Set-up

          When an instrument is to be tested and if necessary adjusted it should be set up on
          firm ground and the tripod should form a stable support.

5.2.2 Horizontal Plate Bubble Adjustment

                Set the instrument up, by means of the bubble, so that the vertical axis is
                 approximately vertical.

                Set the bubble across two foot screws and bring the bubble to the centre of
                 its run.

                Rotate the plate exactly 180 degrees (use the horizontal circle for accuracy).

                If the bubble is in adjustment it will remain central. If not it may be
                 adjusted by taking half the error out with the foot screws and half with the
                 bubble adjusting screws.

          Repeat the procedure to check the adjustment is applied correctly.

5.2.3 Adjustment of the Cross-Hairs

          As the horizontal and vertical adjustments are linked, they should be carried out
          jointly and both conditions satisfied before proceeding to adjustment 5.2.4.

5.2.3.1       Adjustment for Horizontal Collimation

                Select an area of cleared level ground and set up the instrument between
                 point A, a definite point greater than 500 metres away and a tripod
                 approximately 100m from the instrument. Make the vertical axis vertical.




MAIN ROADS Western Australia             Calibration, Testing and Adjustment          Page 6 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
                At point A choose a reference object which is a definite point greater than
                 500 metres away an approximately the same level as that of the instrument.

                At point B set up a horizontal scale or staff so that the top is about the same
                 level as the instrument.

                With the telescope on face left., sight on point at A.

                Transit the telescope and note reading on B.

                Rotate the telescope horizontally and point back at A (it will now be
                 pointing face right).

                Transit the telescope again and note the second reading at B.

                If the readings are identical the instrument is in adjustment. If not the
                 instrument should be adjusted so the line of sight is moved ¼ of the distance
                 towards the first reading.

          Repeat the procedure to check the adjustment is applied correctly.

5.2.3.2       Adjustment for Vertical Collimation

                Set the instrument up so that the vertical axis is vertical.

                Point the telescope so that the top, or bottom, of the vertical hair is aligned
                 on some clearly defined target and clamp the telescope. An example of a
                 well defined point is a plumb-bob hanging from a fixed point.

                Lower, or raise, the sight by means of the vertical circle tangent screw and
                 watch the apparent travel of the target along the vertical hair.

                If the target remains aligned with the vertical hair throughout the whole
                 movement, then the vertical hair is perpendicular to the horizontal axis. If it
                 does not then the instrument must be adjusted until the desired relationship
                 exists. To do this, may upset the horizontal collimation adjustment.

          Repeat the procedure 5.2.3.1 and 5.2.3.2 to check the adjustments have been
          applied correctly.

5.2.4 Horizontal Axis Adjustment

                Set up the instrument with the Vertical Axis exactly vertical.

                Direct the telescope to a clearly defined high point A, example on the top of
                 a high wall. The angle of elevation should be at least 30º.

                Lower the telescope to a horizontal position and make a mark B on the wall.


MAIN ROADS Western Australia             Calibration, Testing and Adjustment            Page 7 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
                Reverse face and repeat the last two steps.

         If the two marks at B coincide the instrument is in adjustment.

                If the two marks do not coincide, direct the line of sight to the mean
                 position at B using the horizontal tangent screw.

                Elevate the telescope to sight A. Because the line of sight has been moved
                 it will not pass through A. The adjustment consists of moving the line of
                 sight until it does pass through A. This is achieved by adjusting screws on
                 the transit axis as per the handbook for the instrument.

         Repeat the procedure to check the adjustment is applied correctly.

5.2.5 Vertical Circle Index Adjustment

                Set the instrument up and level it. Point the line of sight at a wall or a staff.

                Make the vertical circle read 90 or 270 degrees, using the vertical circle
                 tangent screw and, if necessary, the micrometer setting knob.

                Make a mark where the line of sight strikes the wall (or read the staff).

                Change face and repeat the last two steps.

         If the marks (or the readings) coincide the instrument is in correct adjustment,
         otherwise :

                Set the line of sight on the mean reading (using the vertical circle tangent
                 screw). The line of sight will now be horizontal, but changing the line of
                 sight will have altered the zero setting.

                Set the vertical circle to read zero by adjusting either
                      the clip screw, if present, or
                      the vertical circle adjusting device on an Automatic instrument.

         Repeat the procedure to check the adjustment is applied correctly.

5.2.6 Adjustment Screws

         Ensure when adjusting an instrument that the last movement of the adjustment
         screw is clockwise (tightening) to prevent the instrument falling out of
         adjustment.

5.2.7 Recording of Tests

         All tests for the adjustment of optical theodolites, electronic theodolites and total
         stations shall be recorded in a Survey Equipment Field Test Record Book,
         MRWA 236.

MAIN ROADS Western Australia             Calibration, Testing and Adjustment             Page 8 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.3      Testing and Adjustment of Survey Levels

         Survey levels can be tested and adjusted using the procedure known as the ' Two
         Peg Test'.

5.3.1. Set-up One

         Set the instrument up midway between 2 pegs A and B, 60 metres apart on fairly
         level ground. Level the instrument and read the staves at pegs A and B (a1 and
         b1). This will give the true difference in height,  H, between pegs A and B. In
         Figure 1 below, the line of collimation is inclined downwards by an angle causing
         the staff reading at A to be in error by an amount e. Note that because peg B is
         exactly the same distance from the instrument as peg A the same error e occurs.
         This same error e is applied to each staff reading and thus the true difference in
         height can be found.

         Note: This difference may have been determined from previous tests on two fixed
         points. In the case where the true height difference is known this step may be
         omitted. Fixed points shall be tested and results recorded at least once every six
         months




5.3.2. Set-up Two

         Set up approximately 2 metres behind the staff at A, in position 2. Centre the
         circular bubble and record the staff readings a2. Apply the difference in height, 
         H, to reading a2 to predetermine the reading b2. Read the stave at position B, as
         shown in figure 2 below, compare the two values.




MAIN ROADS Western Australia             Calibration, Testing and Adjustment       Page 9 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.3.3 Adjustment

         If the actual reading differs from the pre-determined value b2 by more than 2mm,
         then the level should be adjusted using the adjustment screws on the eyepiece of
         the instrument and in accordance with the handbook for the instrument. Ensure
         the last movement of the adjustment screw is clockwise (tightening) to prevent the
         instrument from falling out of adjustment.

         Always repeat the procedure to ensure the instrument is now in adjustment.

5.3.4 Example of a Two Peg Test




         After readings are taken at the 2nd position, the difference = 0.691 (2.833 -
         2.142), instead of 0.705 (2.074 - 1.369) as at the 1st position. Thus the level has
         an error of 0.705 - .691 = 0.014. The correct reading at B should be 2.847 (2.142
         + .705); the level is adjusted to this reading using the adjustment screws on the
         eyepiece of the instrument and in accordance with the handbook for the
         instrument. For this example, the following would be entered in a Level
         Calibration Field Record Book, MRWA 238. (the tabulation includes a recheck)

         OBSERVER....................................                           DATE........................
           BACK    FORE               RISE            FALL                DIST          REMARKS
          1.369  2.074                              0.705               30 / 30
          2.142  2.833                              0.691                2 / 62    Misc 14mm
                                                                                                      Adjuste
                                                                                                      d
           1.401           2.105                        0.704           30 / 30    Check
           2.151           2.856                        0.705            2 / 62    OK


MAIN ROADS Western Australia             Calibration, Testing and Adjustment                        Page 10 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.4      Calibrated Survey Measuring Band

         The QC(S) shall arrange for all calibrated measuring bands in continuous use to
         be calibrated annually, and for calibrated measuring bands used only for
         standardisation of measuring equipment to be calibrated every five years. The
         calibration shall be performed under DOLA supervision, using an approved
         procedure and certified as to its accuracy.

          The original of the calibration certificate shall be held by the GSC, and a copy
         issued with the calibrated measuring band.

         The QC(S) shall ensure that after calibration all calibrated measuring bands have
         an up-dated Calibration Status Tag.

5.5      Third Order Levelling Staves

5.5.1 Calibration

         The QC(S) shall arrange for the annual calibration of all third order levelling
         staves. The calibration is to be performed under DOLA supervision, using an
         approved procedure and certified as to its accuracy.

         The original of the calibration certificate shall be placed on Main Roads File 15-
         390 “Third Order Stave Calibration Reports”, and a copy issued with all
         calibrated measuring bands.


         The QC(S) shall ensure that after calibration, all calibrated staves to have an up-
         dated Calibration Status Tag.

5.5.2 Calibration Factors

         Staff calibration factors can be obtained from the latest calibration certificate
         attached to the third order staves, or from the original on Main Roads File 15-390
         “Third Order Stave Calibration Reports”.




MAIN ROADS Western Australia             Calibration, Testing and Adjustment        Page 11 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.6      Tribrachs and Optical Plummets

5.6.1 Field Testing Method

                Set tribrach or optical plumb on instrument legs and level using bubbles.

                Using plumb-bob supplied with suitable attachment to instrument legs,
                 mark truly vertical point.

                Remove plumb-bob and check optical plumb for coincidence with point
                 marked in 2.

                Adjust using adjustment screws. Ensure the last movement of the
                 adjustment screw is clockwise (tightening) to prevent the tribrach from
                 falling out of adjustment.

         Repeat the procedure to check the adjustment is applied correctly.

         For tribrachs or optical plummets that can be rotated an alternative method can be
         used by rotating the mechanism through 60 degrees and plotting the circle of
         error. The error can be then removed by the adjustment screws.

5.6.2 Recording

         All tribrachs are to be uniquely identified or tagged and all field tests recorded in
         the Survey Equipment Field Test Record Book, MRWA 236, for the related Total
         Station.

         For checked and adjusted columns below, tick when completed or mark N/A if no
         need for adjustment.

5.6.3 Testing by Head Office Branch

         All Tribrachs are to be forwarded with Total Stations or EDM's for testing to be
         arranged by the QC(S). The associated MRWA 236 book should also be
         forwarded for the recording of the tests.

         Tests shall be undertaken using the test bracket mounted 2m above the floor, on
         the west wall of the main (north) basement car park at Main Roads Don Aitken
         Centre (DAC). A key for the Survey and Mapping key alike padlock will be
         required to remove the access ladder from its storage location in the adjacent
         passage.




MAIN ROADS Western Australia             Calibration, Testing and Adjustment        Page 12 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.7      Minor Survey Equipment

5.7.1 Recording

         All minor survey gear is to be uniquely identified or tagged and all field tests
         recorded in a Survey Equipment Field Test Record Book, MRWA 236, for minor
         survey equipment only.

         For the checked and adjusted columns, tick when completed or mark N/A if no
         need for adjustment.

5.7.2 Levelling Staves

         Levelling Staves are to be tested by a visual inspection of the staff face, condition
         of the foot and joints and measuring with a five metre steel tape, which has been
         tested against a calibrated survey measuring band.

         A comparison of staff graduations against equivalent marks on the steel tape shall
         be made over the entire length of the staff.

         Should any reading disagree by more than 2 millimetres for a 5 mm staff face or 4
         mm for a 10 mm staff face, the staff shall be not be used and clearly marked as
         such.

5.7.3 Poles, Survey Bands, and Tapes

         All Poles, Survey Bands and Tapes shall be tested by a visual inspection for
         condition of the item and by measuring against a calibrated baseline or a
         calibrated survey measuring band.

         All Poles, Survey Bands and Steel Tapes shall not be used if any graduation is in
         error by 5 millimetres or more.

         All fibreglass or cloth Tapes shall not be used if any graduation is in error by 50
         millimetres or more.

5.7.4 Thermometers and Barometers

         Thermometers and barometers shall be tested by comparison against readings
         taken at any Weather Station. If any thermometer is more than 2 degrees in error
         it shall be replaced. Barometers shall be adjusted using the adjustment screw to
         remove any error.

5.7.5 Measuring Wheel

         Measuring wheels shall be tested by a visual inspection for the condition of the
         item and by measurement against a calibrated baseline or calibrated survey band.
         Measuring wheels shall not be used if the measured distance is ±0.1 metres over
         50 metres.


MAIN ROADS Western Australia             Calibration, Testing and Adjustment        Page 13 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
5.7.6 Straight Edge and Wedge

         Straight edges and wedges are to be tested by visual inspection for condition of
         the item. Graduations on the wedges shall be measured against a steel tape.
         Should any reading disagree by more than 2mm, the wedge shall be replaced.

5.7.7 Electronic Spirit Level

         Electronic spirit levels shall be tested by visual inspection for the condition of the
         unit. Calibration of electronic spirit levels shall be completed in accordance with
         the manufacturers instructions and recommended intervals.

5.7.8 Pipe Laying Laser

         Tests as described in the operators manual. If the laser is found to be out of
         adjustment return it to the supplier for factory adjustment.

5.7.9 Electronic Tripmeters

         Establish a calibration bay of known distance (minimum 1km) on a straight and
         flat section of road.

         Align an easily identifiable point on the car (e.g. door locks or wheels) with the
         starting point and set the tripmeter calibration to 100.

         Return the tripmeter back to measuring mode and drive 1 kilometre. Note this
         measurement and repeat. The average of the 2 measurements is the calibration
         figure.

         Drivers should ensure slow and steady acceleration and braking during this
         process.

         Another journey over the calibration bay with the new calibration figure installed
         in the tripmeter should be made. An expected error of not greater than 5m over
         the 1km should be recorded (i.e. ± 0.5% error) or the process should be repeated.

5.7.10 Calibrated Baseline

         There is a calibrated baseline in the main (north) basement car park of the Main
         Roads Don Aitken Centre.




MAIN ROADS Western Australia             Calibration, Testing and Adjustment         Page 14 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc        of Survey Instruments
                                               23/04/04 - Issue 1 10/97
                                                                                  APPENDIX A


                                           FIELD INSTRUCTIONS

                            USING CURTIN CALIBRATION BASELINE


1.       Phone 9351 7373 to confirm availability of baseline. (Baseline cannot be pre booked).

2.       The barometer to be used during the observations is to be calibrated against either the
         one in the store [Room 204.111 of the Engineering & Surveying Building] or another
         calibrated barometer, both before and after the Observation session.

3.       The observation sheet is to be completed in a top down sequence, with ALL spaces
         filled. The Observation sequence MUST NOT be changed.

         Observation notes :

                  If the barometer in the Curtin store is used to calibrate the barometer used in
                   the field, the following steps shall be used to index the Curtin barometer :
                   1)      Rotate the adjustment screw until the index point touches the mercury
                           reservoir.
                   2)      Read off the calibrated barometric pressure using the micrometer.
                  The Instrument, thermometer and barometer are to be shaded with an umbrella.
                   (May be available from Curtin store)
                  The baseline must be clear of foliage : trim/prune as required before
                   commencing observations.
                  Instrument dials should be set to zero - this means temperature and pressure
                   must be booked for each set of distances. For instruments which have internal
                   electronic compensation, the temperature and pressure must be re-entered on
                   instrument, if changed since last set of distances were taken.
                  Care must be taken to ensure that the prisms are mounted in the zero constant
                   position.
                  Barometer readings should be converted and booked as millibars (mb) using
                   the formula at the bottom of the booking sheet.
                  The Slope distance must be observed in single shot measure mode, four times,
                   with the instrument re-pointed between measurements. [Where one reading is
                   considerably different from the remaining three, a fifth reading should be
                   booked in the margin.]
                  Theodolite and Tribrach Foot screws : These must be reset between moves to
                   their mid point, with foot screw adjustments for further set-ups being carried
                   out to maintain the constant height booked in the heading section.

4.       Observation sheets are to be returned to Data Acquisition Section upon completion.




MAIN ROADS Western Australia               Calibration, Testing and Adjustment         Page 15 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc          of Survey Instruments
                                             23/04/04 - Issue 1 10/97 Rev 1
                                                                                                          APPENDIX A



                                                                                   Haymann Road


                                                                              12


                                                                              11

                                                                                           CURTIN UNIVERSITY
                                                                              10
                                                                                                Campus
                                                                              9
                               Kent Street
                                                                              8
                                                                                     Pillars
                                                                              7


                                                                              6


                                                                              5


                                                                              3


                                                                              2          SSM APP 22




                                                                             CURTIN            Main Entrance




MAIN ROADS Western Australia                 Calibration, Testing and Adjustment                               Page 16 of 16
2dc11870-5966-4e40-9266-2432f16ef6d9.doc            of Survey Instruments
                                                   23/04/04 - Issue 1 10/97
                                                                                                      FORMS

See file “23/04/04.xls” for forms 23/04/04/01, 23/04/04/02 and 23/04/04/03 which are part of this procedure

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:17
posted:9/27/2012
language:Latin
pages:17