Field Manual 3-34.331 TOPOGRAPHIC SURVEYING 16 January 2001

TOC Chap1 2 3 4 5 6 7 8 9 10 11 AppA AppB AppC AppD Gl Bib

Chapter 1

Missions, Operations, and Duties

Surveyors determine horizontal and vertical distances between objects, measure angles between lines, determine the direction of lines, and establish points of predetermined angular and linear measurements. After completing field measurements, surveyors use these measurements to compute a final report that is used for positioning by field artillery (FA), air-defense artillery (ADA), aviation, intelligence, communications, or construction control points. Appendix B summarizes the standards for control surveys, Appendix C details the recommended procedures for basic survey computations, and Appendix D includes a list of survey forms.

SURVEY MISSIONS

1-1. Army topographic surveyors support multiple types of survey missions. These missions can be peacetime or wartime oriented.

1-2. Army topographic surveyors support FA and ADA deployable weapons systems by acquiring position and azimuth data as follows:

• FA. FA is a primary user of precise positioning and orientation information in a wartime environment. Topographic-survey support is provided to the multiple-launch rocket-system (MLRS) units, the corps's general-support (GS) units, and other nondivisional assets in the corps area according to FM 6-2. FA requires that topographic surveyors provide monumented survey control points (SCPs) (horizontal and vertical) and azimuthal references for conventional and inertial FA survey teams. FA sometimes requires topographic surveyors to augment FA survey sections.

• ADA. ADA requires positioning and orientation information for ADA systems. ADA and FA have an agreement that FA surveyors (MOS 82C) will provide direct ADA survey support.

1-3. The National Imagery and Mapping Agency's (NIMA's) geodetic survey division maintains US Army topographic surveyors as part of their survey force structure. These surveyors are involved as team leaders, as team members, and in the data-reduction process. In addition, these Army personnel are used in areas or situations where NIMA civilian personnel are not authorized (Saudi Arabia, Somalia, and so on). NIMA has the responsibility to provide earth-orientation data for the Navigation-Satellite Timing and Ranging (NAVSTAR) Global-Positioning System (GPS). NIMA provides correlated World Geodetic System (WGS) 1984 (WGS-84) airfield surveys and geographical and aeronautical database information that are needed to support the aviation approach requirements. NIMA also determines transformation parameters between geodetic systems. In many areas of the world, the transformation parameters are uncertain or unreliable. During times of conflict, Army topographic surveyors may be required to collect data to enable NIMA to better formulate these transformation parameters.

1-4. The US Army Aeronautical Services Agency (USAASA) requires periodic airfield and navigational-aid (NAVAID) surveys and airport obstruction charts (AOCs) according to Army regulation (AR) 95-2. These surveys are extensive field-survey operations that provide aeronautical and other information to support a wide range of National Airspace System (NAS) activities. AOC surveys provide source information on 

• Position.
• Azimuth.
• Elevation.
• Runways and stopways.
• NAVAIDs.
• Federal Aviation Regulation (FAR), Part 77 (FAR-77) obstructions.
• Aircraft movement and apron areas.
• Prominent airport buildings.
• Selected roads and other traverse ways.
• Cultural and natural features of landmark value.
• Miscellaneous and special request items.

1-5. The positioning and orientation information for NAVAIDs is required to certify the airfield instrument-landing approaches. AOC surveys also establish geodetic control in the airport vicinity, consisting of permanent survey marks accurately connected to the National Spatial Reference System (NSRS). This control and the NSRS connection ensure accurate relativity between surveyed points on the airport and between these points and other surveyed points in the NAS, including the navigation satellites.

1-6. The US Air Force (USAF) requires positioning and orientation data for the initialization of Inertial Navigation Systems (INSs), INS test pedestals, NAVAIDs, and compass roses. The USAF relies on NIMA to satisfy all of its positioning and orientation requirements. Army topographic surveyors are currently assigned to assist NIMA in establishing survey control for the USAF.

1-7. The intelligence and signal elements require positioning information for remote-operated vehicles, remote sensing-and-imaging systems, antenna systems' geolocation and direction, inertial navigation initialization, situation awareness, and combat identification. This information includes the following:

• Accuracy. The accuracy requirement for intelligence and signal elements is similar to the accuracy expressed by FA and ADA. In many cases, intelligence and signal units can use the SCPs established for FA and ADA.
• Frequency and timeliness. The number of SCPs and the timeliness are dependent on the battlefield and the mission.
• Distribution. This survey information is distributed to each intelligence and signal battalion's operations section, Operations and Training Officer (US Army) (S3). Topographic surveyors are responsible for notifying the S3 of the various datums within the area of operation (AO). In addition, topographic surveyors provide the S3 with the necessary parameters and instructions on how to transform local coordinates to a predefined common grid (for example, WGS 84).

1-8. During joint-level operations, topographic surveyors may be tasked to perform a number of different missions. Topographic surveyors are capable of providing support to allied nations for any of the aforementioned defined areas.

1-9. These other topographic missions are defined in AR 115-11, FM 5-105, unit table(s) of organization and equipment (TOE), and directives from higher headquarters (HQ). These missions 

• Provide precise positioning to support the updating of the MOS 81T (Terrain Analyst) database.
• Support construction surveyors (when projects require real-world coordinates).
• Establish and extend basic control for field surveys.
• Allow survey data and station description cards to be forwarded to NIMA, the organization's survey information center (SIC), and collocated terrain-analyst teams (upon request).

SURVEY OPERATIONS

1-10. The actual shape of the solid mass of the earth is referred to as the topography. A geoid is defined as the surface of the earth's gravity (attraction and rotation), which on the average, coincides with the mean sea level (MSL) in the open undisturbed ocean. A spheroid (also called an ellipsoid of revolution) appears as a figure that is flattened at the poles and bulging at the equator. It can be described using a mathematical formula that approximately defines a part of the surface of the geoid. However, because of the great variations in topography, many different ellipsoids exist. Because the earth's surface is irregular and pieces of mathematical computations are unreliable, the type of survey conducted depends on the purpose or level of accuracy required.

1-11. In plane surveys, all points are referenced to a flat plane with curvature wholly or mostly ignored. In geodetic surveys, all established points are referenced to the curved surface of a spheroid and, in all computations, the effect of curvature is computed.

Plane Survey

1-12. Plane surveys ignore the actual shape of the earth and apply the principles of plane geometry and trigonometry. These surveys are treated as if the measurements were made on a flat plane, with all lines being straight. When the survey area is less than 250 square kilometers and less accuracy is needed, curvature can be ignored. Most localized construction projects (highway and railroad) and boundary projects use plane surveys.

Geodetic Survey

1-13. Geodetic surveys take into account the size and shape of the earth. Since the stations in geodetic surveys are routinely spaced over extended distances, more precise instruments and techniques are required than for plane surveys. All observations are made on the actual curved surface of the earth and this curvature is corrected through computations.

Conventional Survey

1-14. Topographic surveyors use theodolites, levels, and distance measuring equipment (DME). The automated integrated survey instrument (AISI) provides topographic surveyors with the capability to extend control through the use of a total station.

GPS Survey

1-15. The NAV\STAR GPS is capable of determining accurate positional, velocity, and timing information. The GPS provides positional and navigational data to civilian and military communities in the form of two positional services. The Standard Positioning Service (SPS) encompasses the civilian user and the US Coast Guard (USCG). When using a single GPS receiver (absolute positioning), SPS users are denied the high-accuracy, instantaneous positioning capability of the GPS. The Precise Positioning Service (PPS) consists of military users and authorized representatives. PPS users can obtain high-accuracy, instantaneous positioning if the receiver is capable of accepting the necessary cryptologic variables.

1-16. Absolute and differential (relative) positioning methods using the GPS provide accurate and timely positional data. The method of choice depends on the accuracy required, the equipment available, and the logistical requirements. At present, the PPS GPS receiver, which is capable of performing relative positioning, is the GPS-survey (GPS-S) differential GPS (DGPS). The positioning methods are described as follows:

• Absolute positioning. Absolute positioning uses a single GPS receiver and does not require known survey control. Absolute positions can provide instantaneous (real-time) or postprocessed positions. Known survey control is unreliable or nonexistent in immature theaters. Topographic surveyors can establish SCPs by using absolute positioning.
• Differential positioning. Differential positioning uses two or more GPS receivers. One GPS receiver (reference receiver) is resident over a known SCP. The remaining receivers (remote receivers) are used to position points of interest. Differential positioning can be performed in real time or through postprocessing. If real-time positioning results are required, a communications link that is capable of transmitting digital data must be established at the reference- and remote-receiver locations. This method supports distances up to 100 kilometers between the reference and remote stations. The engineer battalions (topographic) within the Army have PPS GPS receivers that are capable of real-time and postprocessed differential positioning and provide relative accuracy of approximately 1 centimeter.

1-17. The accuracy of GPS-S is dependent on the user's equipment (precise lightweight GPS receiver [PLGR]) and the surveying method employed (absolute real-time or differential). Topographic surveyors have standardized PPS GPS receivers. These receivers have improved the efficiency and productivity of topographic surveyors and have provided the Defense Mapping School (DMS) and the USAES a background on the training, operational, and research and development requirements that are necessary to successfully field the GPS. The new GPS-S provides adequate absolute-positioning results and is designed to provide protection in a jamming/spoofing environment. The requirement for a PPS GPS receiver that is capable of performing DGPS when using the military's authorized, encrypted pseudorandom noise (PRN) code (Y-code) has been met. This receiver satisfies the positional accuracy requirements of the Army, the Department of Defense (DOD), and joint-level commands.

1-18. Topographic surveyors are capable of conducting and supporting a wide variety of surveys. Surveys are classified as follows:

• Artillery.
• Basic control.
• Satellite.
• Construction.
• Airfield engineering and NAVAID.
• Hydrographic.
• Field classification and inspection.
• Land.
• Inertial.

Artillery Surveys

1-19. Artillery surveys are conducted to determine the relative positions of weapons systems to targets. These surveys do not require the accuracy of geodetic-surveying techniques despite the relatively large areas and long distances. The requirements, methods, and techniques used by military FA surveyors are detailed in FM 6-2 and Chapter 11 of this manual. ADA weapon systems require accuracies that are obtainable only from geodetic-surveying techniques.

Basic-Control Surveys

1-20. Basic-control surveys provide horizontal and/or vertical positions of points. Supplementary surveys may originate from and can be adjusted to these surveys. The basic-control survey of the US provides geographic positions and plane coordinates of triangulation/traverse stations and the elevations or benchmarks (BMs). This information is used as the basis for the control of the US national topographic survey; the control of many state, city, and private surveys; and hydrographic surveys of coastal waters. The techniques and methods used by military geodetic surveyors are discussed in this manual.

Satellite Surveys

1-21. Satellite surveys determine high-accuracy, three-dimensional (3D) point positions from signals received by NAVSTAR GPS satellites. GPS-derived positions may be used to provide primary reference-control monument locations for engineering and construction projects from which detailed site plans, topographic mapping, boundary demarcation, and construction-alignment work may be performed using conventional-surveying instruments and techniques.

Construction Surveys

1-22. Construction surveys provide data for planning and cost estimating. This data is essential to locate or lay out engineering works and is recorded on engineer maps. Plane surveys are normally used for construction projects. The methods and techniques used by military construction surveyors are detailed in FM 5-233.

Airfield-Engineering and NAVAID Surveys

1-23. Airfield-engineering and NAVAID surveys are used to determine any combination of the following:

• The location of obstacles within 10 nautical miles of an airfield center.
• The dimensions of runways and taxiways, the height of flight towers, and NAVAIDs.
• The safe approach angles to runways and the minimum, safe glide angle.
• The elevation of the barometer on an airfield.
• The positions and azimuths of points designated for INS checkpoints.
• The requirements of the Federal Aviation Administration (FAA), United States Army Aeronautical Services Agency USAASA, or equivalent military activity.
• The information used to assist a military-aircraft crash or disaster incident investigation.

Hydrographic Surveys

1-24. Hydrographic surveys are made on large bodies of water to determine channel depths for navigation and the location of rocks, sandbars, lights, and buoys. In rivers, these surveys are made to support flood-control projects, power development, navigation, water supplies, and water storage.

Field-Classification and Inspection Surveys

1-25. Field-classification and inspection surveys can help to identify features not normally revealed using a compiler (for example, political boundary lines, names of places, road classifications, and buildings obscured by trees). These surveys can also clarify aerial photographs by using comparisons with actual ground conditions.

Land Surveys

1-26. Land surveys are used to locate the boundaries and areas of tracts of land. These surveys may be done on a city, county, state, national, or international level.

Inertial Surveys

1-27. Inertial surveys are used to determine relative positions and azimuths. The Position and Azimuth Determination System (PADS) is now being used extensively to support artillery surveys.

1-28. Each survey has a fundamental classification of control points called a network. There are several different types of networks. A network of control areas usually establishes horizontal and vertical SCPs within a country. These areas are all referenced to a single datum and are related in position or elevation to each other. Networks are classified as basic, supplementary, and auxiliary. All horizontal networks in the US are referenced to the North American Datum (NAD) of 1927 (NAD 27) and the NAD of 1983 (NAD 83) (NAD 83 and WGS 84 are the same), with coordinates currently being published in both. The National Geodetic Vertical Datum of 1929 (NGVD 29) and the North American Vertical Datum of 1988 (NAVD 88) are used for vertical control points. Within the continental US (CONUS), the following terms are used:

Basic Horizontal-Control Networks

1-29. Basic horizontal-control networks are usually established by first-order geodetic-triangulation, traverse, or GPS procedures. The lines of the basic network are spaced at intervals of about 96 kilometers throughout a country.

Basic Vertical-Control Networks

1-30. Basic vertical-control networks are established by first-order differential leveling along lines spaced from 90 to 160 kilometers apart throughout the country. Permanent BMs (PBMs) are spaced at intervals of about 3 kilometers on these lines.

Supplementary Horizontal-Control Network

1-31. Supplementary horizontal-control networks are usually established by second-order survey techniques. These supplementary networks are used to fill in the areas between the basic-control lines. Ultimately, either a basic or a supplementary network station will be spaced at intervals of about 6 to 16 kilometers across a country.

Supplementary Vertical-Control Network

1-32. Supplementary vertical-control networks are established by second-order differential leveling. These lines are run within the basic-control lines to provide a planned control-line spacing at intervals of about 10 kilometers. PBMs are emplaced at intervals of about 2 kilometers apart on these lines.

Auxiliary Horizontal-Control Networks

1-33. Horizontal auxiliary-control networks are usually established by second- or third-order survey techniques. They provide localized control to be used by surveyors for artillery control, construction-engineering surveys, mapping projects, or other positioning requirements. As more states and other agencies require geodetic accuracy for boundary and property surveys, they will use these networks.

Auxiliary Vertical-Control Networks

1-34. Auxiliary vertical-control networks are established by third-order differential leveling and are used to provide localized vertical control. They are also used to support artillery, construction, and engineering projects.

Conventional Survey Equipment

1-35. Topographic surveyors have theodolites, levels, and electronic DME (EDME) within their inventory. The AISI provides topographic surveyors with the capability to extend control in a timelier and more efficient manner. The AISI is a total station that combines angular, distance, and vertical measurements into a single electronic instrument that is designed to digitally record and transfer data into a personal computer (PC).

NAVSTAR GPS

1-36. The NAVSTAR GPS is capable of determining accurate positional, velocity, and timing information. The PPS consists of military users and authorized representatives. A PPS user can obtain high-accuracy instantaneous positioning if the receiver is capable of accepting the necessary cryptologic variables. When two or more receivers are used, it is called DGPS surveying. The error values are determined and removed from the survey either by real-time processing or postprocessing of the data. The type of DGPS survey used is dependent on accuracy requirements. There are two basic types of DGPS surveys static and dynamic.

• Static survey. Static surveying uses a stationary network of receivers that collect simultaneous observations over a predetermined time interval and yield the best accuracy.
• Dynamic survey. Dynamic surveying uses one stationary receiver and any number of remote or roving receivers. It allows for rapid movement and the collection of data over a large area. When operating in the real-time mode, the roving receiver can provide very accurate positions almost instantaneously on the battlefield.

Computer Information Systems

1-37. Surveying has become a digital science. Modern survey systems work with software specifically designed to process field data, perform computations, and produce a precise product, whether it be a GPS network, a digital database, or a computer-aided design (CAD) and drafting (CADD). GPS-survey computations require a PC to process large amounts of mathematical variables. Efforts should be ongoing to obtain or upgrade to the fastest system available. Computer resources are standardized throughout TOE units with topographic surveyors. Application (such as databases or word processing) and functional (such as adjustment or CAD) software packages have increased the efficiency and productivity of topographic surveyors. The SIC collects and disseminates the positioning and orientation requirements for such organizations as NIMA, FA, ADA, Armor, and the USAF and maintains a digital database capable of archiving, querying, and manipulating survey control. Topographic surveyors are equipped with common GPS hardware and software and CAD and survey-application software.

SURVEY-PERSONNEL DUTIES

1-38. Topographic surveyors supervise and/or conduct surveys to provide control data for mapping, artillery, and aviation support and supervise or perform topographic or geodetic computations. Duties for MOS 82D (at each skill level) are identified below.

1-39. Skill level 1 surveyors 

• Record topographic-survey data.
• Operate and collect data with a GPS, electronic and mechanical theodolites, EDME, and differential-leveling equipment.
• Perform topographic computations; compute elevations of tidal BMs and baselines; and transport, set up, operate, and maintain equipment according to written, oral, or visual instructions from supervisors.
• Prepare abstracts of field data for final computations.
• Assist in the emplacement and recovery of control stations and prepare station description cards.
• Compute abstracted survey data for final tabulation.

1-40. Skill level 2 surveyors 

• Transport, set up, operate, and maintain equipment according to written, oral, or visual instructions from supervisors.
• Make field checks to ensure that field measurements meet project specifications and classifications.
• Perform observations and compare, standardize, and calibrate survey equipment.
• Input field-survey data into CAD programs and process CAD data into final products.
• Transfer, process, and adjust GPS data by using survey software and PCs.
• Compute and adjust first-, second-, and third-order horizontal- and vertical-control surveys.
• Perform preliminary and field computations to verify field observations for control surveys and compute preliminary values of horizontal and vertical control points.
• Convert grid and geodetic coordinates and transform (in the same system) coordinates and azimuths from one zone to adjacent zones.
• Operate and write programs for programmable electronic calculators.
• Operate PCs.
• Direct and control personnel when acting as a survey-party chief.

1-41. Skill level 3 surveyors 

• Supervise and direct topographic surveys.
• Prepare project progress reports and conduct project briefings.
• Recommend the method of computation and adjustment and the need for additional data.
• Evaluate and verify results of all computations.
• Direct the transportation, setup, operation, and maintenance of equipment according to written, oral, or visual instructions.
• Perform a survey recon (to include picture-point selection) and main and secondary survey-station placement and evaluate field data and the results obtained.
• Plan and analyze the collection of traverse, triangulation, leveling, and satellite data and isolate computational or field blunders.
• Supervise CAD survey operations.

1-42. Skill level 4 surveyors 

• Plan and approve topographic surveys.
• Supervise recon studies and reconnoiter survey sites to determine special requirements of obstacles encountered.
• Plan and arrange logistical support for topographic-survey activities.
• Plan and organize work activities.
• Coordinate surveying and computing activities.
• Supervise field-survey activities in support of task and mission requirements.
• Determine composition and operational techniques of topographic-survey parties.
• Perform quality checks on survey data.
• Collect available charts, maps, control lists, aerial photographs, and other topographic data that are necessary to maintain a deployable database.
• Disseminate survey data.
• Serve as the technical authority in all survey matters.

FIELDWORK

1-43. Topographic surveyors perform most of their operational duties away from the parent unit. Topographic surveying involves fieldwork over a project area or battlefield. Survey fieldwork consists of making observations and measurements; recording data; and returning the data to a computer and/or draftsman for computation, compilation, and dissemination. Surveyors must overcome many factors that combine to affect working conditions. They must be constantly alert to various factors such the following:

• Weather and terrain. Weather and terrain can adversely affect field surveys. The effectiveness of optical and electro-optical instruments can be severely reduced by fog, mist, smog, or ground haze. Swamps and floodplains under high water can impede leveling operations. Signals from the GPS constellation generally require a clear line of sight to the sky. Urban and forested areas can mask or deflect the direct signal that is needed for accurate measurements. Good recon and proper planning can alert the field parties of the best times and methods to use.
• Personnel. The rate of progress often varies in direct proportion to the training and experience level of the assigned personnel. The most effective method of training personnel is under conditions where their actions have real consequence as opposed to mere practice. On-the-job training produces a measurable product but frequently results in lost work due to correcting mistakes.
• Equipment. Equipment reliability must be considered when setting completion dates. Modern, well-maintained equipment can often increase the rate of progress. Older equipment, if properly maintained or adjusted, will yield accurate results. Repairing or replacing broken instruments or parts will sometimes slow down or stop a field survey. Equipment must be calibrated as part of combat checks before the survey mission begins.
• Purpose. The purpose and the type of survey will determine the accuracy requirements. Control networks are established by using high-accuracy GPS, triangulation, traverse, or leveling procedures. At the other extreme, cuts and fills for a highway have much lower standards. In some surveys, distances to inaccessible points must be determined. High-accuracy distance and angle measurements are required so that these values, when used in trigonometric formulas, will yield acceptable results. This type of survey is directly dependent on the clearness of the atmosphere. Observing measurements for a single position can be delayed for days while waiting on good weather.
• Accuracy. Accuracy requirements will dictate the equipment and techniques selected. For instance, comparatively rough techniques can be used for elevations in site surveys, but control-network leveling requires much more precise and expensive equipment and extensive, time-consuming techniques.
• Errors. All measurements contain some amount of error. Errors classified as systematic and accidental are the most common uncontrollable errors. Besides errors, measurements are susceptible to mistakes or blunders that arise from misunderstanding the problem, poor judgment, confusion, or carelessness. The overall effect of mistakes and blunders can be greatly reduced by following a preestablished systematic procedure. This procedure will be advantageous in all phases of a survey.
• Progress rates. Rates of progress vary, depending on experience and repetition. As skill and confidence increase, so does speed. Proper preparation and planning reduce duplication of effort and increase efficiency.
• Enemy. A hostile environment often forces a schedule adjustment. Night work requires greater speed, fewer lights, and increased security. Adding security forces increases the number of vehicles and personnel, which in turn, reduces efficiency and retards even the most ambitious time schedule.

1-44. Topographic surveyors observe distances and/or directions (angles) for the following reasons:

• To establish GPS, triangulation, and traverse stations for basic, supplementary, and auxiliary control networks.
• To establish gun and target positions for artillery batteries.
• To establish horizontal control to support PADS.
• To establish point and lines of reference for locating details (such as boundary lines, roads, buildings, fences, rivers, bridges, and other existing features).
• To stake out or locate roads, buildings, landing strips, pipelines, and other construction projects.
• To establish lines parallel to, or at right angles to, other lines or to determine the area of tracts of land, measure inaccessible distances, or extend straight lines beyond obstacles.
• To establish picture points for databases.
• To do any other work that requires the use of geometric or trigonometric principles.

1-45. Topographic surveyors observe differences in elevation (DEs) for the following reasons:

• To establish BMs for basic, supplementary, or auxiliary vertical-control networks.
• To determine DEs of terrain along a selected line for plotting projects and computing grade lines.
• To stake out grades, cuts, and fills for earthmoving and other construction projects.
• For trigonometric elevations of triangulation and traverse stations for control networks and mapping projects.
• To establish gun and target positions for FA batteries.

1-46. Topographic surveyors record field notes to provide a permanent record of the fieldwork. These notes may take any of the following formats:

• Field-recording booklets.
• Single-sheet recording forms.
• Digital disks or devices for automated data recording.
• Land-survey plans.
• Property plans.
• Recovery and station description cards.
• Control diagrams showing the relative location, method, and type of control established and/or recovered.

Even the best field survey is of little value if the field notes are not complete and clear. The field notes are the only records that are left after the survey party leaves the field site. Surveyors' notes must contain a complete record of all measurements or observations made during the survey. When necessary, sketches, diagrams, and narration should be made to clarify notes. Write overs, erasures, or use of correction tape or fluid are strictly forbidden. These actions, when prohibited by the unit's survey standing operating procedure (SOP), are cause for punishment under the Uniform Code of Military Justice. Recording errors are to be lined out and initialed by the recorder and the corrected reading entered on the recording form.

Quality

1-47. Good field notes share the following qualities:

• Neatness. The lettering should conform to the gothic style portrayed in FM 5-553. All entries should be formatted according to unit SOPs.
• Legibility. Only one interpretation should be possible. Decimal points and commas must be clear and distinct.
• Completeness. All entries should be complete, and all resolved data must be finished according to unit SOPs. All entries must 

• Be done on the correct forms and entirely in the field. Never record notes on scrap paper and then transcribe them to a field-recording form. If performing an underground survey, use a covered clipboard to protect the notes.
• Accurately describe the field experience. Sketches, diagrams, and notes will reduce or eliminate questions.

Organization

1-48. Survey notes are usually kept in a field notebook, on individual recording forms, or in an automated data collector. Loose-leaf sheets should be numbered serially to ensure that all sheets are kept and turned in. Regardless of the format used, include 

• The instructions for the return of the notes or cassette tapes (specify any special-handling requirements) in case they are lost. Usually, they should be returned to the commander of the particular unit.
• An index of the field notes and a cross-reference to additional books or binders.
• A list of party personnel and their duties and the project's beginning and ending dates.
• A list of instruments used (include types, serial numbers, calibration dates, constant values, and dates used).
• A generalized sketch and description of the project.
• The actual survey notes on each page that contain data. Fill out the heading and include the following information:

• The station names (include the establishing agency and date).
• The survey date.
• The names and survey duties of personnel (for example, instrument operator or note keeper).
• The instruments used (include the serial numbers).
• Weather data.
• The actual observed data (include all required reductions).
• Pertinent notes, as required.
• The observer's initials at the bottom right corner of the recording form (indicating that the observer has checked all entries and ensures that they are correct).

Format

1-49. Recording of field notes takes three general forms tabulations, sketches, and descriptions.

• Tabulations. Numerical data is recorded in columns following a prescribed format, depending on the type of operation, the instrument used, and the specifications for the type of survey.
• Sketches. Sketches add much to the clarity of field notes and should be used liberally. They may be drawn to scale (as in plane-table surveys), or they can be drawn to an approximate scale (as in control cards). If needed, use an exaggerated scale to show detail. Measurements should be added directly on the sketch or keyed in some way to avoid confusion. Sketches require the same quality as other field notes.
• Descriptions. Tabulations with or without sketches can also be supplemented with narrative descriptions. The description may consist of a few words, or it may be very detailed. Survey notes become a part of historic records, so a brief description entered at the time of the survey may be important and helpful in the future.

1-50. Abbreviations and Symbols. Standard abbreviations, signs, and symbols should be used in all survey notes and must be consistent with guidelines in such publications as AR 310-50 and FMs 21-31 and 101-5-1. Spell out words if there is any doubt about the meaning or interpretation of a symbol or abbreviation.

1-51. Corrections. Field notes are considered legal documents and can be used in court proceedings. As such, no erasures or write overs are permitted. No position will be voided or rejected in the field, except in the case of disturbing the instrument or target or observing the wrong target. In either case, the position should be reobserved and the location of the reobserved data should be noted in the remarks section. Follow these rules for making corrections:

• No erasures. All fieldwork will be done in black or blue-black ink (with no erasures) that is suitable for photocopying. The only exception is the field sheet of a plane-table survey.
• No write overs. Field notes show what happened in the field. If a number is changed, make a single slanted line through the incorrect number. The individual making the corrections inserts the correct number directly above or next to the corrected value, creating the new entry and initialing the change. A note will be entered in the remarks column stating why the number was changed.

OFFICE WORK

1-52. Surveying procedures also consist of converting the field measurements into a more usable form. Usually, the conversions or computations are required immediately to continue the fieldwork. At other times, they must be held until a series of field measurements is completed. This is called office work even though some of the operations may be performed in the field during lapses between measurements. Some office work requires the use of special equipment (calculators, PCs, or drafting equipment) or extensive references and working areas. During survey operations, many field measurements require some form of arithmetical computation. For example, adding or subtracting DEs to determine the height of instrument (HI) or elevation during leveling or checking angles to see that the allowable error (AE) is not exceeded.

1-53. Office computing converts distances, angles, GPS measurements, and rod readings into a more usable form or adjusts a position of some point or mark from which other measurements can be made. This process involves the computation of

• Distances. The desired result is the horizontal distance between two points. In electronic distance measurement (EDM), the distance is usually on a slope and has to be corrected for temperature and barometric pressure and then reduced to the correct horizontal distance.
• Azimuths and bearings. In many operations, the observed angles are converted into directions of a line from north (azimuths) or north-south (bearings).
• Relative positions. The distance and direction of a line between two points determine the position of one point relative to the other point. If the direction is given as an azimuth bearing, a trigonometric formula (using the sine or cosine of the angle multiplied by the distance) can be used to determine a coordinate difference between the two points.

1-54. Some survey techniques are not complete until one or more of the following adjustments are performed. Adjusting is the determination and application of corrections to data. Adjusting provides a means of dealing with the random errors in a survey network and causes the data to be consistent within itself and to a given set of references. Small errors that are not apparent during individual measurements can accumulate to a sizable amount. In a linear adjustment, for example, assume that 100 measurements were made to the nearest unit and required determining which unit mark is closer to the actual measurement. Adjusting the result requires reducing each measurement by the product that results from dividing the error by the number of measurements. Since the measurements were only read to the nearest unit, a single adjustment would not be measurable at any point and the adjusted result would be correct. Some of the more precise surveys require least-square adjustments.

• GPS network and least-square adjustment. A least-square adjustment is the basis for correcting GPS (and traverse) networks that use automation to compute solutions in geometry and produce geodetic accuracy. A least-square adjustment in a survey network allows for the computation of a single solution for each station and minimizes the corrections made to the field observations. A least-square adjustment uses probability in determining the values for particular unknowns, independently weighs all field observations, highlights large errors and blunders that were overlooked before adjustment, and generates information for analysis after the adjustment (including estimates of the precision of its solutions).
• Traverse. Traverse is the measurement of lengths and the determination of directions of a series of lines between known points that establishes the coordinates of the intermediate points. When computed, the accumulated closing error shows up as a position displacement of a known point. The displacement is corrected and distributed among the intermediate (traverse) points.
• Elevation. Depending on the purpose, the elevations on some level lines are computed as the measurements are taken. When the line is closed, the DE between the measured and the known elevation is adjusted over all the stations in the line. In higher-order leveling, only the DEs are recorded during the measuring and all adjusting is done at the completion of the line. The error is then distributed among the various sections of the line.

1-55. Office computations reduce the field notes to a tabular or graphic form. They become a permanent record and are stored for further use or subsequent operations. Many standardized forms are available and should be used. As long as the sheets are clearly identified and bound as a set, they are acceptable. Normally, all field notes should be abstracted and filed separately. The abstracts should be bound along with all computing forms into a single binder or folder and maintained on file for further reference. All pages should have the name and date of the person performing the work and at least one person who verified that page. Do not dispose of or destroy any of these records.

1-56. Surveying involves a series of checks. The field notes should be checked by the observer, the recorder, and the party chief before they are turned in for office work. Before computing, the assigned person should check the notes again. Most mathematical problems can be solved by more than one method. In checking a set of computations, it may be desirable to use a method that differs from the original computation method. An inverse solution may be used, starting with the computed values and solving for the field data or a graphic solution. Each step that cannot be checked by any other means must be checked by a totally independent recomputation by another individual. Any errors or mistakes that are found must be resolved and rechecked before the computation is accepted.

SURVEY COMMUNICATION

1-57. Survey-party members may find themselves separated. The ability to communicate with each other may mean the difference between successfully completing a section of work or not. Even at relatively short distances (as in site surveys or leveling operations), background noises can obscure direct voice contact. At longer distances, such as in EDM or direction-measurement operations, effective direct voice contact is impossible. Therefore, some other type of communication is required.

1-58. On long lines, where hand signals are impossible, a radio must be used. Each theater of operations or Army command has published communications-electronics operation instructions (CEOI) that units must follow. Only frequencies obtained through the local signal officer may be used. All personnel must be familiar with the CEOI and the unit's communications SOP before using a radio. All radio communications must be kept as short and secure as possible.

1-59. Over shorter distances, during all types of site surveys, the AISI provides one-way voice communication. Two-way communication is preferred for short distances. Most units have some type of hand-held radios, although they are not TOE equipment. These radios should be able to communicate up to 5 kilometers and should not be limited to line of sight only. Portability, ease of operation, and frequency programmability should be considered when procuring this type of communication equipment. Military hand-held radios are readily available in most military communities.

1-60. TOE changes are replacing frequency modulated (FM) radios with Single-Channel Ground-to-Air Radio Systems (SINCGARSs). The need to communicate across large distances is increasing in frequency. GPS surveys are conducted at distances of up to 25 kilometers and depend upon synchronization between receivers during data collection. Any disruption from a single station in a GPS network can result in a total loss of effort.

1-61. The primary focus of survey operations during wartime is to operate quickly over large distances. This requires the ability to transmit data digitally over the battlefield. The type of data will be largely or entirely GPS data. In order for a survey team to provide accurate positions where needed and in a timely manner, they need to operate in real time without having to process out the error code embedded in a GPS signal. The process of real-time GPS surveying begins with a base-station receiver that broadcasts corrections to the signals emanating from the GPS satellites. Army surveyors have the following two means of transmitting this data:

• Radio modem. Surveyors have a radio modem that is designed primarily for broadcasting DGPS corrections or raw GPS data from a survey base station to one or more roving receivers for real-time differential or kinematic (RTK) surveying. These radio modems require line of sight between each radio modem. They can be set up in a series of repeating stations that extend across the survey area. This system is effective only over a small, local area.
• SINGARS. The primary system for data transmission over the distances required on the battlefield is SINCGARS. GPS-S is designed to transmit encrypted GPS data over SINCGARS. Any user that can receive the data will have a real-time correction to the broadcast GPS signal. This gives topographic surveyors the operational capability to perform the mission under circumstances where GPS signals are dithered or spoofed on the battlefield. A GPS signal can be retransmitted over a communication network to multiple users, which extends the range and capability of survey operations.

1-62. Mirrors and lights can also be used for communication. A signal mirror can use the sun as a light source and is a fairly accurate sighting device. Morse code or other prearranged signals can be used to effectively communicate during the day. At night, the same signals can be used with a light.