SYSTEM DIVIDENDS APPLICATION GUIDE for Trimble Static/RTK GPS w/Access 2014+ & Trimble Business Center 2.99/3.40+ SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA ABOUT THIS GUIDE The purpose of this training guide is to provide a practical outline and sequential framework for discussion and exploration of the Trimble suite of GPS survey grade receivers and attendant software products, with particular emphasis on the overall process of observing, computing, and adjusting high accuracy survey positions. Its focus is conceptual, not cookbook, and is not meant as a substitute or even as a complete outline of the Trimble manuals which are rich in detail and well indexed (they need to be read), but rather as a guide for discussion and introduction to the Static system. IN SHORT, THE PURPOSE HERE IS TO NAVIGATE THROUGH A PROJECT, NOT TO DOCUMENT THE ENTIRE SYSTEM. While GPS technology is expansive beyond a surveyors dreams in terms of distances covered and precision attained, the few system restrictions are sometimes more absolute than those surveyors normally confront. When you are in a satellite shadow, you are in the dark, there is no GPS evening where you can take just one more observation in the fading light (even though GPS is a 24 hour weatherproof system). In addition, the basis of the GPS observations themselves is markedly different than conventional surveying with total stations or theodolites and EDMs, so some change in thinking of how positions (final coordinates) are determined is necessary, especially when relating the GPS results to established conventional monumentation. The Trimble software is strong with considerable error trapping routines built in and the processing robust enough to handle most data collection situations and subsequent processing. As with all complex methodologies however, GPS observations, vector processing, and final adjustments require sound fundamentals. The most basic components and issues of the actual GPS "machinery" are briefly summarized in the following sections (detailed explanations can be found in the Trimble documentation), but the operative function of this document is to begin generating high accuracy survey positions (expressed in user specific datums and coordinate systems) with all due speed and efficiency by focusing on the overall implementation of GPS as a surveying tool. With careful and prudent regard for the intricacies and components of the system however, GPS will serve you well. The devil is in the details, so take care of the details, or they will certainly take care of you! NOTICE This guide is proprietary to System Dividends. No part of this guide may be reproduced or transmitted by any means without the express written consent of System Dividends. TBC COMBINED W ACCESS 3.40 - 4.DOC 2 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA TABLE OF CONTENTS BASIC WORKING/REFERENCE SURFACES .............................................................................. 8 TGO TO TBC CONVERSION ...................................................................................................... 12 TBC SETUP OPTIONS ................................................................................................................ 13 PROJECTS & DATA FLOW ........................................................................................................ 16 PLANNING ................................................................................................................................... 16 NAVIGATING THE ACCESS SCREENS ..................................................................................... 24 BASIC ACCESS STATIC SETTINGS .......................................................................................... 26 FIELD PROCEDURES & STARTUP – POST PROCESSED ...................................................... 31 GPS STATION OBSERVATION SHEETS ................................................................................... 34 GPS PROJECT OBSERVATION SCHEDULE ............................................................................ 35 CREATING A PROJECT ............................................................................................................. 37 DATA TRANSFER ....................................................................................................................... 42 POINT MANAGEMENT ............................................................................................................... 44 VIEWS .......................................................................................................................................... 53 USING CORS ............................................................................................................................... 62 USING OPUS ............................................................................................................................... 67 USING RTX POST PROCESSING .............................................................................................. 69 BASELINE PROCESSING & EVALUATION ............................................................................... 72 NETWORK ADJUSTMENTS ....................................................................................................... 79 3 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA CONVENTIONAL TRAVERSE ADJUSTMENT ........................................................................... 91 CREATING/EXPORTING ALIGNMENTS .................................................................................... 96 EXPORTING .............................................................................................................................. 102 GETTING STARTED W RTK ..................................................................................................... 107 RTK SURVEY SETUP CONSIDERATIONS & ACCESS CONVENTIONS ............................... 107 BASIC ACCESS RTK SETTINGS ............................................................................................. 109 BEGINNING A SURVEY ............................................................................................................ 117 DATA COLLECTION ................................................................................................................. 134 STAKEOUT ................................................................................................................................ 142 STAKEOUT RESULT FORMATS .............................................................................................. 152 MENU DETAILS ......................................................................................................................... 153 ROADS DETAILS ...................................................................................................................... 153 JOBS MENU .............................................................................................................................. 160 KEY IN MENU ............................................................................................................................ 164 SURVEY MENU ......................................................................................................................... 166 COGO MENU ............................................................................................................................. 167 INSTRUMENT MENU ................................................................................................................ 173 INDEX ........................................................................................................................................ 175 ADDENDUMS ............................................................................................................................ 177 4 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA GPS SURVEY SYSTEM DEFINITION & CAPABILITIES GPS, as originally envisioned by its developer and patron (the Department of Defense), is a worldwide, all weather, highly accurate, and when fully deployed, 24 hour navigation system that has evolved into a technology with vast implications beyond military navigation. Specifically for our purposes, GPS has become a tool without peer for many of the problems facing today's surveyors, especially in regard to large scale, high order projects. With survey grade receivers such as the Trimble 4000/5000/R series, it is now possible to quickly perform high order control surveys on a scale and accuracy level never before contemplated, as well as general boundary, topo and GIS surveys on the local level. Speed and accuracy levels vary with equipment and procedures, but individual observation times of as little as 5 seconds with closures in the range of 1:500,000+ are certainly attainable without undue expenditure of resources, as are much higher closures with 1 hour observations. Trimble has further enhanced the basic positioning function of GPS by developing Real Time Kinematic (+/- 1 cm.) for topography and stake out work as well as incorporating comprehensive least squares network adjustment routines and data output options in the available software packages. The entire system is composed primarily of three segments; the satellites themselves (Space Segment), the earth bound monitoring installations (Control Segment), and the users of the system itself (User Segment). All of these combine to provide what is essentially an extremely high order trilateration system, a technique which should be familiar to most surveyors (albeit a system with considerably more variables than land based trilateration). Essentially what is being measured is not the actual distance between the satellites (known positions) and the receiver(s) (point of intersection), but rather the number of wavelengths (integers) and travel time of the signal. From this data the "satellite to receiver" distances are computed and receiver positions derived. From these receiver positions, the survey "network" components of azimuth, distance, and height are computed and solved using least squares. As with any navigation, survey, or spatial relation system such as a GIS, GPS requires some sort of reference point from which to relate observations. In the case of GPS, the system is referenced to ECEF coordinates which are Earth Centered, Earth Fixed (X,Y,Z) and expressed in WGS-84. After measuring a sufficient number of signals from multiple satellites with an appropriate receiver, the user is then able to compute positions relative to the system reference point (a global Point of Beginning if you will). With some further computation, these positions are processed into baselines, possibly adjusted with least squares, transformed to the ellipsoid, and may then be related to whatever historic or legal reference system was included in the observation network or a local user defined projection, i.e. northing/easting coordinates. It is useful to remember that GPS baselines are essentially the inverse result of two best fit (least square) positions, whereas conventional baselines are the result of direct observation. Both types (GPS & conventional) may be combined and then adjusted (again in the case of GPS) as a network with the least squares program available in TBC. 5 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA STATIC/FAST STATIC GPS NETWORKS Static GPS was the original GPS application in the survey industry and allowed on a practical level the first networks of non-intervisible points and at accuracy levels higher than conventional procedures. By occupying different points simultaneously with GPS receivers and observing/storing the transmitted code and carrier wave signals from at least 4 satellites, distances from the satellites to each receiver can be computed, trilaterated positions can be solved, and the spatial relationship of each point to another derived. In addition to the flexibility of no line of sight requirements and the super increase in relative precision, the distance capability of the system extends to tens of miles with medium effort and hundreds with additional resource. To accomplish this, an occupation campaign must be carried out which includes: simultaneous observations of at least 4 satellites; data logged at common times; and sufficient observation time vs. distance between points, all in an environment sufficiently free of electronic interference and offering a clear view of the satellites. While the receivers are fairly automated in terms of field operations (assuming good survey methods regarding instrument setups and notes), the logistics of moving personnel and equipment efficiently and profitably requires precise planning and intention – static/fast static field operations must be a concerted effort of all involved, that is to say all receivers must be operating together, not individually. Once the data has been collected, the information is downloaded into a computer and comes together in a Trimble Business Center Project for post processing. If the field conditions were nominal the post processing is relatively automated (again assuming good survey techniques were involved in the field work and the observation environment was appropriate) and the software allows various levels of diagnostics and edit/repair tools to ferret out and eliminate bad data. Once the data has been “reduced” it is formatted in positional geodetic terms of WGS (World Geodetic System) latitude/longitude/ellipsoid height or a user defined datum such as NAD83. From this point the data must be projected to a specified coordinate system to be useful in the conventional northing/easting/elevation sense. Note that unlike conventional survey measurements, GPS measures positions and computes the component parts (azimuth/distances). This allows for some additional flexibility in network construction as the GPS networks are not as prone to the deleterious effects of ground geometry as conventional surveys. REAL TIME KINEMATIC (RTK) GPS Kinematic GPS is a general category or technique which employs carrier phase observations in order to compute vectors and positions, similar to the above mentioned “static” GPS. However, in contrast to the “static” method, kinematic GPS observations can be made in seconds rather than the 8 to 20 minutes required by Fast Static or the 1 hour required by the standard Static method. This time difference is obviously a tremendous advantage, but comes at a certain price which is the requirement that the “Rover” unit be able to compute and continually sustain the resolution of the integers (obtained through the measurement of the relationship between the two (+) receivers, and their relationship to the satellites). In normal post-processed kinematic surveying, this is accomplished by maintaining constant lock on at least 4 satellites during the survey, including travel time between actual observations. If satellite lock is lost by the Rover unit, the system must be reinitialized by occupying a known point (known in GPS terms) or returning to the last point surveyed (although dual frequency receivers using Kinematic mode may reinitialize after losing lock by observing an Unknown Point for approximately 8 minutes). This constant “lock” requirement is sometimes difficult, and in some environments, impossible to maintain (freeway overpasses and foliage for example). In addition, the field operator does not have results or know whether the initialization procedure was successful until the data is post processed in the office, long after the fieldwork is performed. 6 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA To overcome these shortcomings, Trimble has developed Real Time Kinematic equipment and software that is available in several different configurations. The primary difference between the most basic RTK and post processed kinematic is that RTK has the additional requirement of a constant land based radio link between the “Base” and “Rover” units in order to differentially correct for ionospheric distortion and other systematic “noise”. While somewhat restricting, this link provides “Real Time” coordinates (both WGS84 lat/long/height and/or local values) which are obviously required for Stake Out, and the knowledge that the survey initialization (and thus the entire survey) is successful while it is being performed. Furthermore, Trimble offers an RTK configuration (available with dual frequency receivers only) that allows re-initialization to be performed either “On The Fly (OTF)” while continuing to move, or by briefly remaining stationary in any convenient location (Known Point). It must be noted however, the “OTF” mode requires a minimum 5 satellite configuration (re-initialization on a Known GPS point only requires 4 satellites, and is in one format or another the only method of re-initialization for single frequency receivers). In all cases, kinematic surveys, whether RTK or post processed, derive “Rover” positions which are totally relative to a “Base” station. The positions of these two receivers are the ends of “GPS vectors” (there can be as many simultaneous vectors from a single “Base” station as there are “Rovers”). While these “side shot” vectors can be projected to whatever coordinate system is required, they remain unverified, similar to topographic “side shots” observed with a total station. As a result, procedures need to be developed to periodically check the survey for errors, similar to returning to the backsight in a conventional total station survey. As the name implies, RTK offers the operator coordinate values as they are surveyed in real time, initially measured, formatted, and stored as WGS84 vectors from the Base (expressed as delta x/y/z Earth Centered Earth Fixed), and then through a calibration process transformed/projected to whatever local coordinate system is required (State Plane, local northing/easting, etc), and importantly, also transformed to the local vertical datum. THE CALIBRATION PROCESS IS NOT NECESSARILY DIFFICULT, BUT IT IS ABSOLUTELY KEY TO SUCCESSFUL, ACCURATE COORDINATE PRODUCTION. Obviously, GPS is a technology that requires many very precise and highly coordinated components AND procedures in order to resolve sub centimeter baselines from radio signals originating some 12,600 miles in earth orbit. There are many esoteric causes for position error (such as radio propagation delays due to the atmosphere, clock error, etc.), but most are handled by the receivers themselves or the software. There are however, procedures and safeguards that can taken to insure that the data collected will be appropriate and satisfy the project. The following is an outline of some of those components and procedures. However, the emphasis here is on the operational procedures, rather than the hardware components themselves or the electrical engineering inherent in the GPS system. The procedures have more user variables and are more susceptible to error or blunders (simply put, you either have appropriate, working receivers, or you don't - how they are used and the resultant data processed, may be another matter). Also, a significant portion of the system (the Space/Control Segments) is largely beyond the user's control. In fact, this guide assumes a certain leap of faith as to the notion that GPS does indeed work, and work well if properly used. As a result, it will concentrate on those areas that fall within the practical influence of the user, and the processes by which the user may be able to mitigate some of the negative effects of the GPS environment. Successful use of GPS is due to understanding not only the individual components, but equally important, their synergy. There are many cause and effect scenarios in this technology, it is important to recognize the effect that one phase or procedure can have on another. 7 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA BASIC WORKING/REFERENCE SURFACES ground WGS84 Geoid (msl) Note that the geoid/ellipsoid relationship here is for the continental US and is reversed in other parts of the world. 8 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA GENERAL SYSTEM REQUIREMENTS & CONNECTIONS COMPONENTS SPACE SEGMENT Navstar Satellites (also referred to as SVs or Space Vehicles) When originally designed, the Space Segment was to consist of 24 satellites providing 24 hour global navigational coverage, as well as approximately 24 hours of daily 3D survey coverage (minimum of 4 satellites). Of the 24 satellites, 21 were to be in actual use, the other 3 to serve as spares that may be placed in service immediately. However, there are currently 32+ SVs in orbit and all are active and operational. The satellites are in an earth orbit of roughly 12,600 miles, and carry very precise (and very expensive) atomic cesium clocks. As any given SVs grow old, orbits decay, or other problems arise, they will be replaced. Glonass Satellites – In addition to the US GPS satellites, the Trimble R Series receivers and TBC can observe and process the data from the Russian Glonass constellation. CONTROL SEGMENT The maintenance and control of the entire GPS system (the SVs themselves and the ground control stations) fall under the aegis of the Department of Defense. The DOD maintains 5 Monitor Stations around the globe to constantly track the satellites and upload new position information. As the system is primarily military, first consideration is always given to military priorities, sometimes to the detriment of civilian use (access to the system is guaranteed by Congress, accuracy is not). USER SEGMENT GPS Receivers, Peripherals, and Processing Software Survey grade receivers establish positions through the trilateration of the distances from at least 4 satellites to each receiver. The distances themselves are derived through an elaborate set of computations which essentially "count" the number of whole radio wavelengths (each wavelength is exactly 19 cm in length) which are known as the integers, plus the fractional wavelength observed when the survey first begins. This technique is known as observing the carrier phase and differs from navigational GPS as well as mapping grade GPS observations (Trimble Pathfinder) in that both of these later techniques "time" the signal's journey from the satellite to the receiver to derive the distances (this method is known as code phase). The practical difference between these two methodologies is significant: carrier phase observations can be resolved to sub-centimeter levels with RTK or post processing, whereas code phase observations typically yield accuracies of 0.5 to 5 meters +/- with differential processing. How integers are observed and solved is the subject of many volumes and post graduate degrees and will not be detailed here as the principles are beyond the scope of this guide. Suffice it to say that the parameters for this method (carrier 9 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA phase) places certain restrictions on GPS observations which will be discussed. The minimum number of required receivers for survey precision work is 2 (operating at the same time), however, 3 or more receivers will greatly reduce the overall time necessary to complete a project, especially in the observation of a static network. In the RTK context, multiple rovers increase production arithmetically. While specific products types and versions are mentioned below, bear in mind that this technology is rapidly changing and evolving, and care must be taken to verify compatibility issues such as product models, software/firmware versions, data formats, and communication parameters. Trimble 4000 Series Survey Grade Receivers (SL, ST, SE, SSE, SSi, 4600LS, 4400, 4700, & 4800) and 5700/5800/R Series Single Frequency - SL, ST, & SE Firmware Types and Processing Potential (all of the following "types" require a minimum of 4 qualified satellites, however 5 are strongly recommended to insure successful observations!!! Standard Static - requires approximately 1 hour observations of 4 satellites yielding the highest GPS accuracies (up to 1:5,000,000). The 4600LS, 4700/4800 & 5700/5800/R Series receivers use an internal clock to determine the minimum time required for static observations, from 20 minutes with 6+ SVs to 30 minutes for 4 SVs. Dynamic Kinematic - requires observations as short as 5 seconds after initialization, with constant "lock" on a minimum of 4 satellites, even when traveling between observations. The 4600LS will only perform Kinematic surveys using the Access Controller. RTK (as this category of receivers is single frequency, “On The Fly” initialization is not available) - after initialization on a known point requiring a minimum of 4 satellites (approx. 1 minute), requires approximately 2 seconds to update a position with +/- 1 cm. accuracy. Requires special firmware in addition to a ground radio link. Dual Frequency - SST, SSE, SSi, 4400, 4700/4800, & 5700/5800/R Series Firmware Types and Processing Potential Both Standard & Dynamic listed above as well as Fast Static. Fast Static - approximately 8 to 20 minute observations of a minimum of 4 to 6 satellites respectively yielding medium accuracies of 1:1,000,000. (Can only be processed with TBC.) 10 SYSTEM DIVIDENDS, THE MOST EXPERIENCED GPS TRAINERS IN AMERICA