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EDM CALIBRATION HANDBOOK Land Victoria Department of Sustainability and Environment Edition 11 December 2010 EDM Calibration Handbook Edition 11. Date: December 2010 EDM Calibration Handbook Edition 11. Date: December 2010 ..

    EDM CALIBRATION HANDBOOK

    Land Victoria

    Department of Sustainability and Environment

    Edition 11

    December 2010

EDM Calibration Handbook Edition 11. Date: December 2010

Geodetic Survey

    Office of Surveyor-General Victoria

    Land Victoria

    Department Of Sustainability and Environment

EDM Calibration Handbook

    Edition 11

    December 2010

ISBN 1 74106 023 0

Copyright The State of Victoria, Department of Sustainability and Environment, 2010.

Disclaimer

This publication may be of assistance to you but the State of Victoria and its employees do not

    guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular

    purposes and therefore disclaims all liability for any error, loss or other consequence which may arise

    from you relying on any information in this publication.

Handbook Errors and Discrepancies

Land Victoria would appreciate notification of any errors or discrepancies found in this handbook.

    Please direct any correspondence to:

Calibration Officer

    Office of Surveyor-General Victoria

    Land Victoria

    570 Bourke Street

    Melbourne Victoria 3000

Find more information go to www.dse.vic.gov.au/property

    EDM Calibration Handbook Edition 11. Date: December 2010

Preface

    In relation to measurement, the professional surveyor is intent not only on getting it right, but in proving that it is. To achieve this, surveyors rely on their measuring equipment which must be systematically tested for errors and compared to the national standard.

    John E Tulloch

    Surveyor-General of Victoria

    The Surveyor-General of Victoria sets standards for property surveys under the Surveying (Cadastral Surveys) Regulations 2005, including requirements for the calibration and standardisation of survey equipment. To assist licensed surveyors in meeting these standards, the Surveyor-General is responsible for issuing practical implementation advice and providing certified calibration facilities. The Surveyor-General of Victoria Practice Directives, January 2007 addresses the requirements

    regarding calibration of Electro-optical Distance Meter (EDM) instruments. It states that EDM instruments must be calibrated over a certified baseline at intervals not exceeding 12 months, or more frequently, if conditions warrant it. It also states that a Licensed Surveyors Report must detail calibration information about the EDM used in the survey including: make and model, serial number, EDM calibration site and date of calibration.

    This EDM calibration handbook provides the specification and practice direction for achieving EDM calibration at each of the six baselines across the state. The Surveyor-General is a Verifying Authority for length (up to 1160 metres) and is responsible for the annual re-certification of the baselines as subsidiary standards of length.

    The Surveyor-General, through the Geodetic Survey, provides the continued certification of the baselines and the periodic updates of the handbook, and acknowledgement is also made of the assistance of Land Victoria staff throughout the state.

    The Surveyor-General acknowledges the cooperation and support provided by Brayley & Hayes Pty. Ltd.; SMEC Urban Pty. Ltd. (Gippsland); and St. Quentin Consulting Pty. Ltd.; for their assistance with the Hamilton, Loy Yang and Geelong baselines, respectively.

John E Tulloch

    Surveyor-General of Victoria

    December 2010

    EDM Calibration Handbook Edition 11. Date: December 2010

Table of Contents

CHAPTER 1: INTRODUCTION .......................................................................................................... 1

    CHAPTER 2: LEGAL TRACEABILITY OF LENGTH MEASUREMENTS ........................................... 2 Survey Practice Directive - September 2006 ................................................................................... 3

    Surveying (Cadastral Surveys) Regulations 2005 ............................................................................ 3 Survey Co-ordination Regulations 2004 .......................................................................................... 4

    CHAPTER 3: THE THEORY OF EDM CALIBRATION ....................................................................... 5 Instrument Errors ............................................................................................................................ 5

    Baseline Design .............................................................................................................................. 6

    Pillars and Ground Marks ................................................................................................................ 6

    CHAPTER 4: RECOMMENDED OBSERVING PROCEDURES .......................................................... 8 General Procedures ........................................................................................................................ 8

    Measurement Sequence (Excluding the Bendigo and Geelong Baselines) ...................................... 9 Measurement Sequence Bendigo and Geelong Baselines Only .................................................. 10 Loy Yang Baseline.. ……………………………………………………………………………………...

    10

LOCATION OF BASELINES ............................................................................. 错误;未定义书签。11

Unit Lengths of EDM ....................................................................................................................... 19

    CHAPTER 5: REDUCTION AND INTERPRETATION ...................................................................... 23 REFERENCES ................................................................................................................................. 24

    APPENDIX A SAMPLE BOOKING SHEETS ................................................................................. 25

EDM Calibration Handbook Edition 11. Date: December 2010

Chapter 1: Introduction

    1.1 This handbook deals with the calibration and standardisation of Electro-optical Distance

    Meters (EDM) in the State of Victoria.

    1.2 There are now six baselines in Victoria that are maintained as subsidiary standards of length

    and as such are suitable for the calibration and standardisation of EDM. The new Geelong

    baseline was created in 2008. The baselines are of Sprent/Zwart (Hobart) design with the

    exception of the Bendigo and Geelong baselines, which are a modified Schwendener design.

    1.3 Calibration of EDM is concerned with the determination of instrument errors, whereas

    standardisation refers to the comparison of the instrument to a standard of length traceable to

    the National Standard. Instruments must be calibrated within a prescribed level of precision in

    order to be standardised. Chapter 2 discusses the legal background of standardisation.

    1.4 The theory of EDM calibration is summarised in Chapter 3 along with an explanation of the

    instrument errors that are determined.

1.5 The observing procedures outlined in Chapter 4 are based on the Instructions on the

    Verification of Electro-optical Short-Range Distance Meters on Subsidiary Standards of Length

    in the Form of EDM Calibration Baselines proposed by Dr. J.M. Rueger (1984).

    1.6 EDM users who wish to perform calibrations need to book the use of baselines in advance.

    Chapter 4 lists the baselines and the offices that can be contacted to make bookings and

    obtain further information.

    1.7 The program Baseline is described in Chapter 5. Previously, the reduction software

    provided by the Surveyor-General was EDMInput. From 1 January 2007 this software was no

    longer maintained and was replaced by Baseline. Baseline was developed by Landgate in

    Western Australia and adopted by the Surveyor-General of Victoria because it fully addressed

    the requirements of the ISO Guide to the Uncertainty of Measurement. Baseline produces

    several reports for analysing an EDM instrument calibration and for analysing a calibration of a

    baseline. A certificate which summarises the results of an EDM instrument calibration is also

    produced.

    1 EDM Calibration Handbook Edition 11 Date: December 2010

Chapter 2: Legal Traceability of Length Measurements

    2.1 A surveyor's field tape measurements can be traced to the national standard of length. The

    Surveyor-General maintains a standard tape that is regularly compared with the national

    standard for length. Surveyors compare their standard office tape against the standard tape

    that is maintained by the Surveyor-General. The surveyor’s field tape can be compared

    against their standardised office tape on a regular basis.

    2.2 In accordance with Regulation 73 of the National Measurement Regulations 1999, the

    Surveyor-General of Victoria is appointed as a Verifying Authority with respect to length. This

    enables certification of subsidiary standards of length to a certain precision pursuant to

    Regulation 13 of the National Measurement Regulations 1999.

    2.3 Although not common, the validity of length measurement may be challenged in a court of

    law. The validity will be strengthened if traceability to the national standard can be proved.

    2.4 In 1983 the National Standards Commission (NSC), now incorporated into the National

    Measurement Institute (NMI), formed a working party on the Calibration of Electromagnetic

    Distance Measuring (EDM) Equipment’. Following both the recommendations of this working

    party and research by the NSC, it was established that monumented baselines could be

    certified as subsidiary standards of length under Regulation 13 of the National Measurement

    Regulations 1999 to provide legal traceability for EDM measurements.

    2.5 The standard of length was transferred to baselines through use of standard tapes or EDM as

    prescribed by the National Standards Commission. The Kern Mekometer and the Comrad

    Geomensor were the only EDM prescribed by the NSC. These instruments needed to be

    compared with the national frequency standard and certified as reference standards prior to

    their use for baseline certification.

    2.6 The Kern Mekometer ME3000 owned by Melbourne Water/WBCM Surveys Pty Ltd has been

    used to certify the Victorian baselines in the past. When this instrument ceased operating in

    1994, the Kern Mekometer ME5000 owned by Hydro Tasmania was used for this purpose. In

    2006, the Leica TCA2003 total station owned by the Department of Transport Energy and

    Infrastructure South Australia and certified by NMI was used to re-verify the five EDM

    baselines. In 2008, the Office of Surveyor-General Victoria purchased a Leica TCA2003 total

    station which is used to certify the six baselines. This class of instrument is expected to be

    used in the near-medium future.

    2.7 An EDM is considered to measure distances traceable to the national standard of length if:

     (a) it is calibrated on a certified baseline,

     (b) it is calibrated in accordance with the procedures laid down herein,

    (c) the current inter-pillar distances (as determined from re-verification measurements) are

    used to compute the calibration and

     (d) the instrument correction has been computed to a prescribed level of precision.

    2.8 Recommendations of specific interest from the NSC working party referred to in 2.4 and 2.7

    above are:

    No.2 To be certified as a subsidiary standard a baselines must be capable of being -3 calibrated with an uncertainty of ?(1.5 + 20 x 10x L) mm at the 95 per cent of

    confidence where L is the interval length in metres.

    No.8 It is recommended that, in general, the minimum standard for the uncertaintly of

    calibration of an EDM, assuming calibration against a monumented base, should be -3?(5 + 30 x 10 x L) mm at the 95 per cent of confidence where L is the interval length

    in metres.

     Six Victorian baselines are certified annually in accordance with Recommendation No.2.

     The calibration procedures outlined in this handbook and the analysis techniques contained in

    Baseline are capable of meeting the requirement of Recommendation No.8.

    2 EDM Calibration Handbook Edition 11 Date: December 2010

2.9 Survey Practice Directives January 2007

     The Surveyor-General sets standards for surveying title boundaries through the Surveying Act

    2004, Surveying (Cadastral Surveys) Regulations 2005, and standards of measurement under

    the Survey Co-ordination Regulations 2004.

    These standards include calibration and standardisation of survey equipment, record keeping

    and reporting, specifications for units of measurement and levels of precision achievable.

     The Surveyor-General issues practice directives to aid licensed surveyors in the interpretation

    of Regulations and inform them of changes to the requirements of either the Surveyors

    Registration Board of Victoria and/or the Surveyor-General.

    The Surveyor-General of Victoria Practice Directives, January 2007, addresses the Surveyor-

    General’s requirements regarding calibration of Electro-optical Distance Meter (EDM)

    instruments.

     The Surveyor-General has determined that an adequate survey equipment comparison

    process requires the calibration of EDM surveying instruments over a baseline certified

    by the Surveyor-General at intervals not exceeding twelve months.

     Where adverse conditions of use warrant it, more frequent EDM calibration may be required,

    including after every repair to all or part of such equipment.

     Where an EDM surveying instrument is used in a cadastral survey, the Surveyor-General

    requires the following information to be included in the surveyor's report:

     Make and model of instrument

     Serial Number

     EDM Calibration Site

     Date of Calibration

     The Surveyor-General has determined that survey plans signed after 31 January 2002 must

    comply with these requirements in relation to EDM survey instrument calibration.

     Note that complete copies of the Surveyor-General of Victoria Practice Directives are

    available from:

     Deputy Surveyor-General

     Office of Surveyor-General Victoria

     570 Bourke Street

     Melbourne Vic 3000

     Telephone (03) 8636 2525

     or by going to: www.dse.vic.gov.au/surveying > Government surveying services > Practice

    Directives

2.10 Surveying (Cadastral Surveys) Regulations 2005

     Regulations 6(1)(a) and (b) require a licensed surveyor to use survey equipment that has

    been compared to a standard of measurement and that the process of comparison and the

    basis of comparison are adequate to obtain the accuracy required under the Surveying

    (Cadastral Surveys) Regulations 2005.

     Regulation 6(2) requires licensed surveyors to retain records of comparisons and make them

    available for inspection upon request by the Surveyor-General.

     Regulation 15(2)(b) stipulates that a Licensed Surveyors Report must provide details on the

    date of calibration of measuring equipment used in the cadastral survey.

    3 EDM Calibration Handbook Edition 11 Date: December 2010

2.11 Survey Co-ordination Regulations 2004

     Regulation 13 of the Survey Co-ordination Regulations 2004 requires surveyors to use and

    maintain survey equipment that has been compared to a standard of measurement. The units

    of measurement are specified in Regulation 13(a)(i) and levels of precision to be achieved are

    set out in Regulation 13(b).

    2.12 It is considered that the requirements of the Surveying (Cadastral Surveys) Regulations 2005

    and the Survey Co-ordination Regulations 2004 are satisfied for EDM if points (a) to (d) in

    section 2.7 are performed.

    4 EDM Calibration Handbook Edition 11 Date: December 2010

Chapter 3: The Theory of EDM Calibration

    3.1 EDM calibration is performed in order to determine the instrument errors. The instrument

    errors can be used to monitor the performance of the EDM over time and if significant, should

    be applied to measurements taken subsequent to the calibration.

    3.2 If the calibration is performed over a certified baseline to a prescribed level of precision, the

    EDM is considered to be standardised.

3.3 Instrument Errors

3.3.1 Additive Constant (correction for Zero or Index Error)

     All distances measured by a particular EDM/reflector combination are subject to a constant

    error. It is caused by three factors:

     (a) electrical delays, geometric detours, and eccentricities in the EDM;

     (b) differences between the electronic centre and the mechanical centre of the EDM; and

     (c) differences between the optical and mechanical centres of the reflector.

     The additive constant or zero/index correction is added to measured distances to correct for

    these differences.

     Note that this error may vary with changes of reflector, after jolts, with different instrument

    mountings and after service.

3.3.2 Scale Error

     The scale error describes errors that are linearly proportional to the length of line measured.

    These can arise from:

    (a) variations in the modulation frequency of the EDM;

    (b) non-homogeneous emission/reception patterns from the emitting and receiving diodes

    (phase inhomogeneities);

    (c) unmodelled variations in atmospheric conditions which affect the velocity of propagation;

    (d) errors in the collection and use of atmospheric data, which includes the use of

    uncalibrated thermometers/barometers not taking atmospheric measurements in the

    shade and the incorrect entry of the atmospheric correction into the EDM.

3.3.3 Cyclic Error (Short Periodic Error)

     Cyclic error is a function of the internal phase measurement of an EDM. Error in the internal

    phase measurement is caused by unwanted feed through the transmitted signal onto the

    received signal.

     Cyclic error is usually sinusoidal in nature with a wavelength equal to the unit length of the

    EDM. The unit length is the scale on which the EDM measures the distance, and is derived

    from the fine measuring frequency. Unit length is equal to one half of the modulation

    wavelength of an EDM (Rueger 1980).

     As cyclic error repeats itself for every unit length contained within a measured distance, its

    sign and magnitude varies depending on the length measured. The magnitude of the error

    could be in the order of 510 mm, however in modern EDM it is usually less than 2 mm

    (negligible). Cyclic error can increase in magnitude as the components of an EDM age.

    5 EDM Calibration Handbook Edition 11 Date: December 2010

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