Operational Requirements for RTK GPS Surveying Government of

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Operational Requirements for RTK GPS Surveying Government of Powered By Docstoc
					   Technology and Environment Directorate - Road and Traffic Engineering Branch


Document No. 67/08/15                                                    Issue Date 04/2005




              OPERATIONAL REQUIREMENTS FOR
                 REAL-TIME KINEMATIC (RTK)
         GLOBAL POSITIONING SYSTEM (GPS) SURVEYING



This document is owned and controlled by the Survey and Mapping Manager.

The Senior Geodetic Surveyor is the delegated custodian.

All comments for revision should be submitted to the Senior Geodetic Surveyor.




Authorisation

As Executive Director Technology and Environment Main Roads Western Australia, I
authorise the issue and use of this standard.




         .............................……….………………
         EXECUTIVE DIRECTOR TECHNOLOGY AND ENVIRONMENT

         Date: _____/ _____/ _____




No controlled copies are issued for this standard.
The latest copy of this standard is located on the Main Roads Internet site.


MAIN ROADS Western Australia               REAL-TIME KINEMATIC (RTK) GLOBAL
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REVISION STATUS RECORD

  Page        Latest           Latest                        Revision
   No        Revision         Revision                 Description/Reference
               No              Date
    1

    2

    3

    4             1          07.06.04                  Inserted acronym VRS.

    5             1          07.06.04           Inserted document number 67-08-53.

    6             1          07.06.04      Inserted in section 5.2.1: “This section is not
                                           relevant to VRS users.”

    7

    8             1          07.06.04          Section 5.2.2: Reference to appendix A
                                            removed; section cross referencing updated,
                                              reference to document 67-08-50 inserted.

    9             1          07.06.04       Section 5.3:Reference to document 67-08-50
                                                              inserted

   10             1          07.06.04         Section 6.2: Reference to VRS inserted.

   11




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                                                       CONTENTS


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

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

3.       REFERENCES ......................................................................................................... 4

4.       ACRONYMS ............................................................................................................ 4

5.       SPECIFICATION FOR RTK GPS SURVEYS .................................................... 5

         5.1     RTK GPS Validation ...................................................................................... 5

         5.2     Methods of Survey .......................................................................................... 6

                 5.2.1 Reference receiver and antenna set-up and operation ...................... 6

                 5.2.2 Roving receiver and antenna set-up and operation ........................... 7

         5.3     Quality Control ............................................................................................... 9

         5.4     Liaison ............................................................................................................. 9

6.       DOCUMENTATION ............................................................................................... 10

         6.1     Reference receiver and antenna .................................................................... 10

         6.2     Roving receiver and antenna ......................................................................... 10


7.       APPENDICES .......................................................................................................... 11

         Appendix A: Sample RTK GPS base-station log sheet ....................................... 11




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1.       PURPOSE

         The purpose of this document is to specify the operational requirements of Real-
         Time Kinematic (RTK) Global Positioning System (GPS) surveys conducted for
         Main Roads Western Australia (MRWA).


2.       SCOPE

         This Standard is issued to all consultants and contractors who propose to use RTK
         GPS survey methods for work to be submitted to MRWA, unless otherwise
         approved by the Survey and Mapping Manager.

         Advice and further information can be obtained by contacting the Senior Geodetic
         Surveyor of the Road and Traffic Engineering Branch.


3.       REFERENCES

         The following documents relate to this Standard:

              Survey and Mapping Specification 67-08-43, Digital Ground Survey
              Survey and Mapping Specification 67-08-46, Quality Statement
              Survey and Mapping Specification 67-08-36, Road Reference Marks
              Survey and Mapping Specification 67-08-37, Minor Control
              Real-time Kinematic GPS Work Instruction 67-08-50
              Real-time Kinematic GPS Validation Procedures 67-08-53
              Geocentric Datum of Australia Technical Manual
              ICSM – Standards and Specifications for Control Surveys version 1.5 2002
               (SP1)
              Featherstone, W.E. and M.P. Stewart (1999) RTK GPS Evaluation, Contract
               Report to Main Roads Western Australia, Perth, Australia, 50pp.


4.       ACRONYMS

         The following acronyms used in this document have the specific meanings
         indicated.

           AHD                         -   Australian Height Datum
           AUSGeoid                    -   National geoid model
           BM                          -   Benchmark
           GDA                         -   Geocentric Datum of Australia
           GPS                         -   Global Positioning System
           ICSM                        -   Inter-governmental Committee on Surveying and Mapping
           MGA                         -   Map Grid of Australia
           RM                          -   Reference Mark
           RRM                         -   Road Reference Mark
           RTK                         -   Real-time kinematic
           SSM                         -   Standard Survey Mark
           VRS                         -   Virtual Reference Station



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5.       SPECIFICATION FOR RTK GPS SURVEYS


5.1      RTK GPS Validation

         All RTK GPS equipment and software/firmware used for contract surveys to
         MRWA must first have been tested and validated on the RTK GPS Testing and
         Benchmarking Facility at Curtin University of Technology using the techniques
         and software specified in Real-time Kinematic GPS Validation Procedures
         67-08-53.

         The results of the RTK GPS validation will be used by MRWA to determine the
         type of surveys that can be conducted for MRWA using that equipment.


         This validation is essential for both the RTK GPS equipment and the
         software/firmware, and holds for all surveys subsequently conducted using only
         this RTK GPS equipment and software/firmware. The validation is required if the
         RTK GPS equipment is hired.

         If a new set of RTK GPS equipment and software/firmware, or a new version of the
         software/firmware, is to be used for contract surveys for MRWA, a re-validation
         must be undertaken. Only the Survey and Mapping Manager can approve
         exceptions to this requirement (eg. minor changes in a software/firmware upgrade).


         Consultants or contractors to MRWA can perform the validation themselves using
         the techniques and software specified in Real-time Kinematic GPS Validation
         Procedures. The results of this verification must be included with the contract
         survey results submitted to MRWA.

         Alternatively, independent validation and certification can be performed, on behalf
         of MRWA, at a cost of $200 per data set by the Departmentof Spatial Sciences at
         Curtin University of Technology. The data must be delivered in the format
         specified in Real-time Kinematic GPS Calibration Procedures. If not, an additional
         fee will be charged at $160 per hour for data reformatting. The consultants at
         Curtin University of Technology will issue a certificate, which must be included
         with the contract survey results submitted to MRWA. The consultants at Curtin
         University of Technology will not conduct the RTK GPS surveys.


         Consultants and contractors to MRWA are not to contact Curtin University of
         Technology regarding the validation or for a copy of the Real-time Kinematic GPS
         Calibration Procedures. All queries and requests should be directed to the Senior
         Geodetic Surveyor of the Road and Engineering Traffic Branch.




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5.2      Methods of Survey

         For the purpose of this Standard, two modes of RTK GPS survey are defined.

         1.      Fixed-point surveys - coordination of marked points, survey monuments or
                 ground features that can be accurately resurveyed. These marks are
                 permanent or semi-permanent such that they may be resurveyed at some time
                 in the future.

         2.      Pick-up surveys – coordination of features that have no monumentation or
                 ground features that cannot be accurately resurveyed. The distinguishing
                 feature of pick-up surveys is that individual points cannot be reoccupied as
                 part of a field-validation procedure.

         All coordinates derived from either mode of RTK GPS survey must be computed
         with respect to geodetic survey control on the appropriate geodetic datums.

         An experienced operator must always conduct RTK GPS surveys for MRWA.


5.2.1 Reference Receiver and Antenna Set-up and Operation

This section is not relevant to VRS users.
     Reference GPS receivers and antennae (aka RTK GPS base-stations) must be
       established such that the roving-to-reference GPS receiver separation will be no
       greater than 5km (ideally 2km) at any stage of the survey.

       Reference GPS antennae must be set up over a control point of known quality
        (either an existing SSM or a new geodetic control station established in accordance
        with Survey and Mapping Specification 2300/05/06, Minor Control, or Survey and
        Mapping Specification 2300/05/07, Road Reference Marks).

       The coordinates of the control point must be known in three dimensions (geodetic
        latitude, longitude and ellipsoidal height) with respect to the GDA94. If these
        control coordinates have been transformed from other geodetic datums, the
        transformation technique and parameters must be specified.

       The position of any existing control points must be verified by check measurements
        to RMs before they are adopted and used.

       The appropriate height of the antenna’s phase centre must be measured, recorded,
        and input into the reference or roving GPS receiver as required by the RTK GPS
        equipment and software/firmware being used.

       There should be no obstructions to the GPS satellite signals intruding into the space
        formed by a cone of 15-degrees elevation above the horizon of the reference GPS
        antenna.

       The site of the reference GPS antenna must be uncontaminated by probable sources
        of multipath and electrical interference (eg. strong radio transmitters or high-
        voltage power lines).

       The reference receiver must be correctly configured to generate and transmit RTK
        GPS corrections compatible with the roving RTK GPS receiver(s).
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      The GPS data-sampling rate should be as fast as possible (preferably one-second).

      A standard log sheet (see example in Appendix A) must be completed for each
       reference station occupation, which includes the following information.
        Name, identification number and type of control point (eg. SSM, RRM);
        Receiver make, model and receiver serial number;
        Antenna make, model and serial number;
        Firmware/software make and version number;
        Antenna set-up information (orientation, antenna height measurements [true
          vertical or slope height], antenna set-up diagram);
        Start and stop time of the receiver;
        Approximate sky visibility plot of the reference site;
        Three-dimensional coordinates of the reference point (including datums), and
          any transformation methods and parameters used;
        Any unusual site features (including any possible sources of multipath and
          electrical interference);
        Any unusual occurrences during the survey (eg. power failure, inclement
          weather conditions).


5.2.2 Roving Receiver and Antenna Set-up and Operation

        The roving GPS receiver must be configured with the appropriate height of the
         roving GPS antenna’s phase centre, which must be updated if the roving GPS
         antenna height is changed during the survey.

        The GPS data-sampling rate of the roving GPS receiver should be as fast as
         possible (preferably one-second) and must be the same as that of the reference GPS
         receiver.

        The roving-to-reference GPS receiver separation must be no greater than 5km
         (ideally 2km) at any stage of the survey. This restriction does NOT apply to VRS
         users.

        There should be no significant obstructions to the GPS satellite signals intruding
         into the space formed by a cone of 15-degrees elevation above the horizon of the
         roving GPS antenna.

        The site of the roving GPS antenna must be uncontaminated by probable sources of
         multipath and electrical interference (eg. strong radio transmitters or high-voltage
         power lines).

        Current RTK GPS corrections must be received from the reference receiver or VRS
         network for each point coordinated and for the entire time that measurements are
         collected to determine that point’s position.

        Each site to be coordinated must be occupied for a minimum of five (5) continuous
         GPS epochs (preferably 20 or more). Importantly, this occupation period must be
         the same as that used for the RTK GPS equipment and firmware/software
         validation (Section 5.3)

        A minimum of five (5) GPS satellites (preferably 6) must be observed for each
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         point coordinated and for the entire time that measurements are collected to
         determine that point’s position.

        The Position Dilution of Precision (PDoP) must be less than 6.0 for each point to be
         coordinated and for the entire time that measurements are collected to determine
         that point’s position.

        The roving receiver must indicate that an ambiguity-fixed GPS position solution
         has been achieved for each point to be coordinated and this must be maintained for
         the entire time that measurements are collected to determine that point’s position.

        All other proprietary software/firmware quality indicators must be satisfied for each
         point to be coordinated and these must be maintained for the entire time that
         measurements are collected to determine that point’s position.

        The proprietary quality indicators used must be described in the project report and
         included with the results submitted (Section 5.3).

        During each survey, fixed-points (beginning of Section 5.2) must be resurveyed
         once every 30 minutes. These fixed-points must be at a distance no greater than
         1km from the area in which the survey is being conducted. The resurveyed
         positions must be validated (including documentation and justification) according
         to one or a combination of the procedures in section 6 of this document.

        If the resurveyed position disagrees with the previously determined position by
         more than the positional tolerance set by MRWA, the RTK GPS system must be re-
         initialised, the fixed-point resurveyed and checked, and all points surveyed since
         the previous survey of the fixed point must be resurveyed.

        All horizontal positions must be referenced to the GDA94 (or MGA94). If these
         coordinates have been transformed, the transformation technique and parameters
         must be specified.

        All vertical positions must be referenced to the AHD.

        The geoid modelling technique(s) used to derive the AHD heights from GPS
         ellipsoidal heights must be documented and justified according to one or a
         combination of the procedures in section 7 of MRWA Work Instruction 67-08-50.

        A standard log sheet (see example in Appendix A) must be provided for each GPS
         roving receiver, which includes the following information.
         Receiver make, model and receiver serial number;
         Antenna make, model and serial number;
         Firmware/software make and version number;
         VRS Users only: Name of VRS network provider.
         Antenna set-up information (antenna height measurements [true vertical or slope
            height], antenna set-up diagram);
         Date, Start and stop time of the receiver;
         Number of satellites, PDoP and number of epochs used for each point surveyed
         Any unusual site features (including any possible sources of multipath and
            electrical interference);
         Any unusual occurrences (including time) during the survey (eg. power failure,
            loss of radio link, unscheduled re-initialisation, inclement weather conditions).
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         Where practicable, the GPS antennas should be of the same make and model. If
         not, the RTK GPS software/firmware must be able to make appropriate corrections
         for the different phase centres. VRS users must ensure they are using a GPS
         antenna that is approved by their VRS network provider.

         Where practicable, the roving and reference GPS antennae should be oriented in the
         same direction so that common phase centre variations cancel.

         Where practicable, the roving GPS antenna should be stabilised over the unknown
         point using a bi-pod or tripod.


5.3 Quality Control

         The burden of proof is on the consultant or contractor to demonstrate to MRWA
         that quality control criteria listed in Sections 5.2.1 and 5.2.2 have been met for all
         points, either by direct analysis or unequivocal implication.

         Consultants and contractors are referred to RTK GPS Work Instruction 67-08-50
         for quality control procedures for RTK GPS surveying.

         The consultant or contractor must supply the quality indicators listed in Sections
         5.2.1 and 5.2.2 and any other information to allow MRWA to ensure that this
         Specification has been met.


5.4      Liaison

         Consultants and contractors to MRWA are not to contact Curtin University of
         Technology regarding these RTK GPS survey specifications.

         All queries and requests should be directed to the Senior Geodetic Surveyor of the
         Road and Traffic Engineering Branch.

         Contact: Geoff Xanthis

         (08) 9323-4152 (direct)
         (08) 9323-4449 (fax)
         geoff.xanthis@mrwa.wa.gov.au




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6.       DOCUMENTATION

         All RTK GPS surveys must include the following documentation and be forwarded
         to the Senior Geodetic Surveyor of the Road and Traffic Engineering Branch for
         audit.

         All data are to be supplied as per the following specifications:
          Survey and Mapping Specification 67-08-43, Digital Ground Survey
          Survey and Mapping Specification 67-08-46, Quality Statement

         A written survey report should also be included with the equipment and methods
         used, and any other information that expedites audit by MRWA.


6.1      Reference GPS receiver

         The information required for the reference GPS receiver includes:
          A standard log sheet for each reference station;
          Documentary evidence that the Specifications in Section 5.2.1 have been met.

         VRS users must provide information as to the name of their VRS provider.

6.2      Roving GPS receiver

         The information required for the roving GPS receiver includes:
          Documentary evidence that the Specifications in Section 5.2.2 have been met;
          Fixed-points used and results of field validation;
          Number of satellites, PDoP and number of epochs used for each point surveyed;
          Times of scheduled and unscheduled re-initialisations;
          Any other proprietary quality indicators;
          Geoid modelling techniques used to determine AHD heights.




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Appendix A: Sample RTK GPS base-station log sheet




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                MAIN ROADS
                Western Australia


        REAL-TIME KINEMATIC (RTK) GPS BASE-STATION
SAMPLE LOG SHEET                                                                                          Page 1
     Company name                            Observer Name (print)              signature           Survey date




                                                 Receiver Information

                                     Manufacturer                      Model                   Serial Number

  Base Receiver

  Base Antenna

 Base Receiver Firmware version number

                                              Control Point Information

             Name                                Identification number                Type (eg SSM, RRM)



                                                  GDA Coordinates

      Latitude                         Longitude                 Ellipsoidal height             Geoid height



                  Coordinates as input into reference receiver (if different to above)
Tick as appropiate           Long. or Easting         Lat. Or Northing        Ellips.Height         Geoid height
 MGA

 AGD84

 AMG

 Other
                                                                                                  continued over




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                   MAIN ROADS
                   Western Australia


           REAL-TIME KINEMATIC (RTK) GPS BASE-STATION
SAMPLE LOG SHEET                                                                                              Page 2
If GDA coordinates were not used to for base station coordinates state below how the coordinate
used were derived eg source, transformation method, transformation parameters




Antenna plan (indicate to which points on the antenna
                                                                                         Site visibility
measurement were made)
                                                                                              0°
                                                                                  330°                 30°

                                                                           300°                               60°


                                                                                                                 90°
                                                                                              60°
                                                                           240°                30°            120°
                                                                                              15°
                                                                                  210°        0°       150°
                                                                                     Measurement type eg:
Antenna set-up                         tick     Heights: Before        Heights:      L1 phase centre
                                                logging (m)            After logging bottom of notch on ground plane
                                                                                     base of antenna
                                                                       (m)           corner of antenna base


Pillar                                          1

Tripod                                          2

Tribrach                                        3

Optical plummet                                 4

Plumb bob                                       5
Antenna height input into receiver (m)

Transmission Started                                                      Time frame (eg UT,
                                                                          WAST)
Transmission Stopped                                                      Time frame (eg UT,
                                                                          WAST

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