EM 1110-1-1003
1 July 2003




US Army Corps
of Engineers

ENGINEERING AND DESIGN



NAVSTAR Global Positioning
System Surveying
















ENGINEER MANUAL

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DEPARTMENT OF THE ARMY EM 1110-1-1003




US Army Corps of Engineers
CECW-EE

Washington, DC 20314-1000

Manual
1 July 2003
No. 1110-1-1003
Engineering and Design
NAVSTAR GLOBAL POSITIONING SYSTEM SURVEYING


Table of Contents

Subject
Paragraph
Page

Chapter 1
Introduction

Purpose .....................................................................................................................1-1
1-1
Applicability.............................................................................................................1-2
1-1
Distribution...............................................................................................................1-3
1-1
References ................................................................................................................1-4
1-1
Background ..............................................................................................................1-5
1-1
Use of Manual ..........................................................................................................1-6
1-2
Scope of Manual.......................................................................................................1-7
1-2
Life Cycle Project Management Applicability.........................................................1-8
1-3
Metrics and Accuracy Definitions............................................................................1-9
1-3
Trade Name Exclusions............................................................................................1-10
1-3
Abbreviations and Terms .........................................................................................1-11
1-4
Mandatory Requirements .........................................................................................1-12
1-4
Governing Engineer Regulations and Related Standards.........................................1-13
1-4
Proponency and Waivers..........................................................................................1-14
1-4

Chapter 2
Operational Theory of NAVSTAR GPS

General .....................................................................................................................2-1
2-1
Global Positioning System (GPS) Overview............................................................2-2
2-1
NAVSTAR GPS Program Background....................................................................2-3
2-1
NAVSTAR System Configuration ...........................................................................2-4
2-2
GPS Broadcast Frequencies and Codes....................................................................2-5
2-5
GPS Broadcast Messages and Ephemeris Data........................................................2-6
2-6
GPS Status and Problem Reporting..........................................................................2-7
2-8
GPS User Operating and Tracking Modes ...............................................................2-8
2-10
Absolute GPS Positioning Techniques.....................................................................2-9
2-10
Differential or Relative GPS Positioning Techniques ..............................................2-10
2-11
NAVSTAR GPS Modernization Initiatives (2003-2014).........................................2-11
2-11

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Subject
Paragraph
Page

Chapter 3
GPS Reference Systems

General .....................................................................................................................3-1
3-1
Geodetic Coordinate Systems...................................................................................3-2
3-1
WGS 84 Reference Ellipsoid....................................................................................3-3
3-2
Horizontal Datums and Reference Frames...............................................................3-4
3-2
Transforming between Horizontal Survey Datums ..................................................3-5
3-5
Orthometric Elevations.............................................................................................3-6
3-7
WGS 84 Ellipsoidal Heights ....................................................................................3-7
3-9
Orthometric Height and WGS 84 Ellipsoidal Elevation Relationship .....................3-8
3-9
Geoid Undulations and Geoid Models .....................................................................3-9
3-10
North American Vertical Datum of 1988 (NAVD 88).............................................3-10
3-11
Using GPS to Densify Orthometric Elevations ........................................................3-11
3-12
GPS Vertical Site Calibration...................................................................................3-12
3-13
GPS Time References...............................................................................................3-13
3-15

Chapter 4
GPS Absolute Positioning Determination Concepts, Errors, and Accuracies

General .....................................................................................................................4-1
4-1
Absolute Point Positioning .......................................................................................4-2
4-1
GPS Absolute Position Solution Process--Pseudoranging .......................................4-3
4-2
GPS Point Positioning Accuracies ...........................................................................4-4
4-4
Positional Accuracy Statistics--Root Mean Square..................................................4-5
4-5
GPS Range Error Budget..........................................................................................4-6
4-7
User Equivalent Range Error....................................................................................4-7
4-11
Satellite Geometry Effects on Accuracy--Geometrical Dilution of Precision..........4-8
4-12
Resultant Positional Accuracy of Point Positioning.................................................4-9
4-14

Chapter 5
Differential or Relative Positioning Determination Concepts

General .....................................................................................................................5-1
5-1
Differential Positioning Concepts ............................................................................5-2
5-1
Differential Positioning (Code Pseudorange Tracking) ...........................................5-3
5-2
Differential Positioning (Carrier Phase Tracking)....................................................5-4
5-4
Carrier Phase Survey Techniques.............................................................................5-5
5-5
Real-time Kinematic (RTK) GPS.............................................................................5-6
5-7
Differential GPS Error Sources ................................................................................5-7
5-8
Differential GPS Accuracies ....................................................................................5-8
5-9
Differential GPS Augmentation Systems .................................................................5-9
5-11

Chapter 6
GPS Applications in USACE

General .....................................................................................................................6-1
6-1
Project Control Densification ...................................................................................6-2
6-3
Facility Site Plan Topographic Mapping and GIS Surveys
6-3
6-4
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Subject
Paragraph
Page

Shallow Wetland Mapping .......................................................................................6-4
6-5
Flood Control Projects--Levee Assessments............................................................6-5
6-6
Navigation Project Survey Vessel and Dredge Control ...........................................6-6
6-6
Hydraulic and Hydrology Studies ............................................................................6-7
6-8
Structural Deformation Surveys ...............................................................................6-8
6-9
Construction Stakeout and Grading..........................................................................6-9
6-10
Coastal Engineering Surveys....................................................................................6-10
6-10
Photogrammetric Mapping Control..........................................................................6-11
6-11

Chapter 7
GPS Receiver and Equipment Selection

General ....................................................................................................................7-1
7-1
Types of GPS Receivers...........................................................................................7-2
7-1
GPS Receiver Selection Considerations...................................................................7-3
7-2
Military Grade GPS Receivers .................................................................................7-4
7-5
GPS Receiver Manufacturers ...................................................................................7-5
7-6
Other Auxiliary Equipment ......................................................................................7-6
7-7
Resource Grade GIS Mapping Receivers.................................................................7-7
7-8
Common Data Exchange Formats............................................................................7-8
7-10
GPS Training and Operation Manuals......................................................................7-9
7-13
Guide Specifications for Procuring Geodetic Quality GPS Receivers .....................7-10
7-13

Chapter 8
Planning Data Collection with GPS

Scope ........................................................................................................................8-1
8-1
General Planning Considerations for GPS Surveys .................................................8-2
8-1
Project Control Function and Accuracy ...................................................................8-3
8-2
Selection of a GPS Survey Technique......................................................................8-4
8-8
Planning Differential Code Phase GPS Surveys ......................................................8-5
8-9
Field Reconnaissance for GPS Surveys....................................................................8-6
8-10
Technical Criteria for Carrier Phase GPS Horizontal Control Surveys....................8-7
8-18
Recommended Static Baseline Occupation Times for
Horizontal Control Surveys ..............................................................................8-8
8-23
Network Design and Layout for Carrier Phase GPS Horizontal Control Surveys ...8-9
8-24
Planning Vertical Control Surveys using Carrier Phase GPS ..................................8-10
8-29
Technical Criteria for GPS Vertical Densification...................................................8-11
8-30
Orthometric Elevation Guidelines............................................................................8-12
8-30
Additional Guidelines and Recommendations for
Planning GPS Vertical Densification ...............................................................8-13
8-33
Cadastral Survey Standards and Guidelines using GPS ...........................................8-14
8-35
Field Planning Considerations for GPS Surveys ......................................................8-15
8-36
Mandatory Criteria ...................................................................................................8-16
8-38
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Subject
Paragraph
Page

Chapter 9
Conducting GPS Field Surveys
General .....................................................................................................................9-1
9-1
General GPS Field Survey Procedures.....................................................................9-2
9-1

Section I--Conducting Absolute GPS Positioning and Navigation Surveys
General .....................................................................................................................9-3
9-12
Absolute Point Positioning Techniques....................................................................9-4
9-12
Absolute GPS Navigation Systems ..........................................................................9-5
9-12
Mapping Grade GPS Receivers................................................................................9-6
9-13

Section II: Conducting Differential GPS Code Phase Positioning and Mapping Surveys
General .....................................................................................................................9-7
9-15
USCG DGPS Radiobeacon Navigation Service.......................................................9-8
9-15
FAA Wide Area Augmentation System (WAAS)....................................................9-9
9-18
FAA Local Area Augmentation System (LAAS).....................................................9-10
9-20
OmniSTAR Wide-Area Differential Positioning Service ........................................9-11
9-21
LandStar Differential GPS Service (Thales) ............................................................9-12
9-23
Code and Carrier Phase Wide Area Augmentation Services....................................9-13
9-24

Section III: Conducting Differential GPS Carrier Phase Surveys
General .....................................................................................................................9-14
9-25
Ambiguity Resolution ..............................................................................................9-15
9-25
Static Carrier Phase Field Survey Techniques .........................................................9-16
9-26
Rapid/Fast Static Surveying Procedures...................................................................9-17
9-27
Kinematic GPS Survey Techniques .........................................................................9-18
9-29
Stop-and-Go Kinematic Field Survey Techniques ...................................................9-19
9-29
Pseudo-Kinematic Field Survey Techniques............................................................9-20
9-31
Real-Time Kinematic (RTK) Field Surveying Techniques......................................9-21
9-32
RTK Survey Field Procedures and Calibrations.......................................................9-22
9-34

Chapter 10
Post-Processing Differential GPS Observational Data

General .....................................................................................................................10-1
10-1
General Differential Reduction Techniques .............................................................10-2
10-1
Carrier Phase Observables........................................................................................10-3
10-2
Baseline Solution by Linear Combination................................................................10-4
10-2
Baseline Solution by Cycle Ambiguity Recovery....................................................10-5
10-5
Field/Office Baseline Processing..............................................................................10-6
10-6
Resultant Baseline Output and Quality Criteria .......................................................10-7
10-8
Examples of Baseline Reduction Software Output ..................................................10-8
10-12
Baseline Reduction Summaries ................................................................................10-9
10-17
Baseline Reduction in Mapping Grade GPS Receivers............................................10-10
10-19
Field/Office Loop Closure Checks ...........................................................................10-11
10-20
On-Line Positioning User Service (OPUS) ..............................................................10-12
10-23
Scripps Coordinate Update Tool (SCOUT)..............................................................10-13
10-28
Automated GIPSY Analyses (Jet Propulsion Laboratory) .......................................10-14
10-29
Baseline Data Management and Archival ................................................................10-15
10-29
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Subject
Paragraph
Page

Chapter 11
Adjustment of GPS Surveys

General .....................................................................................................................11-1
11-1
Adjustment Considerations ......................................................................................11-2
11-1
GPS Error Measurement Statistics ...........................................................................11-3
11-2
Survey Adjustments and Accuracy ..........................................................................11-4
11-4
Free or Minimally Constrained Adjustments ...........................................................11-5
11-7
Fully Constrained Adjustments ................................................................................11-6
11-8
Partially Constrained Adjustments ...........................................................................11-7
11-10
Rigorous Least Squares Adjustments of GPS Surveys ............................................11-8
11-11
Network Adjustment Software Used in Corps .........................................................11-9
11-12
Network Adjustment Criteria ...................................................................................11-10
11-13
Baseline Weights--Covariance Matrix .....................................................................11-11
11-14
Adjustment Output Statistics....................................................................................11-12
11-16
Minimally Constrained Adjustment Considerations ................................................11-13
11-16
Relative Baseline Accuracy Estimates .....................................................................11-14
11-17
Normalized or Standardized Residuals.....................................................................11-15
11-18
Outlier Tests and Reject Criteria ..............................................................................11-16
11-19
Positional Accuracy Statistics and Error Ellipses.....................................................11-17
11-21
Sample GPSurvey Network Adjustment--San Juan PR Flood Control Project........11-18
11-24
Sample Network Adjustment--Virginia Key, FL Disposal Area Site ......................11-19
11-29
Sample Network Adjustment--Everglades National Park
Modified Water Deliveries ..................................................................................11-20
11-36
Approximate Adjustments of GPS Networks...........................................................11-21
11-43
Geocentric Coordinate Conversions.........................................................................11-22
11-49
Evaluation of Adjustment Results ............................................................................11-23
11-52
Final Adjustment Reports, Submittals, and Metadata ..............................................11-24
11-53
Mandatory Requirements .........................................................................................11-25
11-59

Chapter 12
Contracting GPS Surveying Services

General .....................................................................................................................12-1
12-1
Brooks Architect-Engineer Act`...............................................................................12-2
12-1
Contracting Processes and Procedures .....................................................................12-3
12-1
Indefinite Delivery Contracts and Task Orders........................................................12-4
12-2
Contract Price Schedule ...........................................................................................12-5
12-3
Sample Cost Estimate for Contracted GPS Survey Services....................................12-6
12-5
Cost Per Work Unit (GPS Station) Schedule ...........................................................12-7
12-6
Contract Specifications and Accuracy Standards.....................................................12-8
12-6
Contract Statements of Work ...................................................................................12-9
12-7
Contract Quality Control and Quality Assurance.....................................................12-10
12-7
Task Order Time and Cost Estimates .......................................................................12-11
12-7
Sample Task Order for GPS Services.......................................................................12-12
12-8

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Appendix A References

Appendix B Abbreviations and Acronyms

Appendix C Contract Schedules for GPS Surveying Services

Appendix D Application: Dredge Material Disposal Area RTK Cross-Sections
(Jacksonville District)

Appendix E Application: Photogrammetric Mapping Control Surveys of Nine Mile Run
(Pittsburgh District)

Appendix F Application: Static GPS Control Survey--Coyote Dam, Russian River, CA
(Sacramento District)

Appendix G Application: Structural Deformation Reference Network Survey--Dworshak


Dam, Idaho (Walla Walla District and Topographic Engineer Center)

Appendix H Application: Upper Saginaw River, MI Navigation Project--Second-Order
GPS Photo Mapping Control Surveys (Detroit District)

Appendix I
Application: Rio Guamani, Puerto Rico Section 205 Flood Control Project--
GPS Horizontal and Vertical Control Densification (Jacksonville District)

Appendix J Application: Upland Disposal Area GPS Control Survey--Manatee Harbor,
FL (Jacksonville District)

Glossary
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Chapter 1
Introduction
1-1. Purpose
This manual provides technical specifications and procedural guidance for surveying and mapping with
the NAVSTAR Global Positioning System (GPS). It is intended for use by engineering, planning,
operations, real estate, and construction personnel performing georeferenced feature mapping or accurate
control surveys for civil works and military construction projects. Procedural and quality control
standards are defined to establish Corps-wide uniformity in the use of GPS by hired-labor personnel,
construction contractors, and Architect-Engineer (A-E) contractors.
1-2. Applicability
This manual applies to all USACE commands having responsibility for the planning, engineering and
design, operation, maintenance, construction, and related real estate and regulatory functions of civil
works, military construction, and environmental restoration projects. It applies to GPS survey
performance by both hired-labor forces and contracted survey forces. It is also applicable to surveys
performed or procured by local interest groups under various cooperative or cost-sharing agreements.
1-3. Distribution
This publication is approved for public release; distribution is unlimited.
1-4. References
Referenced USACE publications and related bibliographic information are listed in Appendix A. Where
applicable, primary source material for individual chapters may also be noted within that chapter. Up to
date information on GPS systems, processes, equipment, and vendors may be obtained through the US
Army Topographic Engineering Center's GPS web site: http://www.tec.army.mil/info_links.html.
1-5. Background
GPS surveying is a process by which highly accurate, three-dimensional point positions are determined
from signals received from satellites. GPS-derived positions may be used to provide the primary
reference control monument locations for engineering and construction projects, from which detailed site
plan topographic mapping, boundary demarcation, and construction alignment work may be performed
using conventional surveying instruments and procedures. GPS surveying also has application in the
precise positioning of marine floating plant and photogrammetric mapping aircraft, and in monitoring
structural deformations of locks and dams. GPS control surveying techniques are also used for the rapid,
real-time geospatial feature mapping of wetlands, facilities, utilities, and related geographical information
system (GIS) products. USACE commands first began using GPS in 1983, primarily for establishing
precise positions on fixed monuments to control navigation and military construction projects. In the
early 1990s, commands began using dynamic GPS for real-time control of hydrographic survey vessels
and dredges, and real-time topographic mapping. In the later 1990s, GPS applications expanded to
precise airborne positioning for photogrammetric mapping and Light Detection and Ranging (LIDAR)
terrain modeling applications. Simply operated hand-held GPS receivers using wide-area augmentation
networks will now provide accurate, real-time geospatial coordinate and feature data for an expanding
and unlimited number of USACE positioning and navigation applications.
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1-6. Use of Manual
This manual is intended to be a USACE reference guide for a variety of GPS applications, including:
precise control surveying, topographic site plan mapping, GIS feature mapping, positioning, and
navigation. These activities may be performed by hired-labor forces, contracted forces, or combinations
thereof. It is also used as the primary reference manual for Proponent Sponsored Engineer Corps
Training (PROSPECT) courses on GPS surveying. General planning criteria, field and office execution
procedures, and required accuracy specifications for performing GPS surveys in support of USACE
engineering, construction, operations, planning, and real estate activities are provided. Accuracy
specifications, procedural criteria, and quality control requirements contained in this manual shall be
directly referenced in the scopes of work for Architect-Engineer (A-E) survey services or other third-party
survey services. This is intended to assure that uniform and standardized procedures are followed by both
hired-labor and contract service sources throughout USACE. Throughout the manual, recommended GPS
surveying and mapping criteria are normally summarized in tables. Technical or procedural guidance is
in more general terms where methodologies are described in readily available references or in GPS
instrumentation and software operating manuals. Where procedural guidance is otherwise unavailable
from industry sources, it is provided herein.
1-7. Scope of Manual
The original version of this manual was developed in the late 1980s and published on 14 June 1991 by the
USACE Engineer Topographic Laboratory at Fort Belvoir (now the Topographic Engineering Center
under the Engineer Research and Development Center--ERDC). The 1991 version was subsequently
revised on 31 December 1994 and 1 August 1996. These original versions contained detailed GPS
theory, operational instructions, procedures, and equipment procurement guidance, and were based on the
technology and observational methods that were still evolving during that period. Since GPS theory and
observational methods are now covered in various DoD technical documents, academic publications,
and/or GPS equipment manufacturer's manuals, the current update is more focused on specific USACE
project applications, accuracy standards, observation criteria, and adjustment analysis.
a. General coverage. This update to the manual primarily focuses on the use of static and
kinematic differential carrier phase GPS survey techniques for establishing and/or extending project
horizontal and vertical construction control, boundary control, and topographic site plan mapping. Both
static and kinematic control survey methods are covered, along with related GPS data reduction, post-
processing, and adjustment methods. Absolute GPS point positioning methods (i.e. non-differential) and
code-phase differential navigation positioning from wide-area augmentation networks are covered to a
lesser extent since these techniques are not normally employed for establishing high-accuracy control
coordinates on project reference monuments. These techniques do, however, have an expanding
application on many USACE surveying and GIS feature mapping projects. Dynamic differential
code/carrier-phase GPS positioning methods supporting hydrographic surveying and dredge control are
also covered in EM 1110-2-1003 (Hydrographic Surveying). Airborne mapping and LIDAR applications
of GPS are covered more fully in EM 1110-1-1000 (Photogrammetric Mapping). High-precision uses of
GPS for monitoring structural deformations are more thoroughly described in EM 1110-2-1009
(Structural Deformation Surveying).
b. Manual coverage and appendices. The first few chapters in this manual are intended to
provide a general overview of the theory and physical concepts of satellite GPS positioning, including
coordinate systems and reference datums. Subsequent chapters cover GPS survey planning, data
acquisition, data processing, and data adjustment and analysis. The final chapter on estimating costs for
GPS surveys is intended to assist those USACE commands that contract out these services. The
appendices to this manual contain detailed examples of GPS surveys covering a variety of Corps
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Document Outline

• Cover
• Transmittal Letter
• Table of Contents
• Chapter 1 - Introduction
• Chapter 2 - Operational Theory of GPS
• Chapter 3 - GPS Reference Systems
• Chapter 4 - GPS Absolute Point Positioning Determination Concepts, Errors and Accuracies
• Chapter 5 - Differential or Relative Positioning Determination Concepts
• Chapter 6 - GPS Applications in USACE
• Chapter 7 - GPS Receiver and Equipment Selection
• Chapter 8 - Planning Collection with GPS
• Chapter 9 - Conducting GPS Field Surveys
• Chapter 10 - Post-Processing Differential GPS Observational Data
• Chapter 11 - Adjustment of GPS Surveys
• Chapter 12 - Contracting GPS Surveying Services
• Appendix A - References
• Appendix B - Abbreviations and Acronyms
• Appendix C - Contract Schedules for GPS Surveying Services
• Appendix D - Application: Dredge Material Disposal Area RTK Cross-Sections
• Appendix E - Application: Photogrammetric Mapping Control Surveys of Nine Mile Run
• Appendix F - Application: Static GPS Control Survey
• Appendix G - Application: Structural Deformation Reference Network Survey
• Appendix H - Application: Upper Saginaw River, MI Navitation Project
• Appendix I - Application: Rio Guamani, Puerto Rico Section 205 Flood Control Project...
• Appendix J - Application: Upland Disposal Area GPS Control Survey..
• Glossary

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