surveying iii (topographic and geodetic surveys) - Modern Prepper

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PART A - GLOBAL POSITIONING SYSTEM OVERVIEW5-1. Operating and Tracking Modes. There are two general operating modes from which GPSderivedpositions can be obtained--absolute and relative or differential positioning. Within each of thesetwo modes, range measurements to the satellites can be performed by tracking either the phase of thesatellite's carrier signal or PRN codes that are modulated on the carrier signal. In addition, GPSpositioning can be performed with the receiver operating in a static or dynamic (kinematic) environment.This variety of operational options results in a wide range of accuracy levels, which may be obtainedfrom the NAVSTAR GPS. Accuracies can range up to 100 meters and down to less than a centimeter.Increasing the accuracy to less than a centimeter requires additional observation time and can beachieved in real time. Selection of a particular GPS operating and tracking mode (such as absolute,differential, code, carrier, static, kinematic, or combinations thereof) depends on the user application.Topographic survey applications typically require differential positioning using carrier phase tracking.Absolute modes are rarely used for geodetic surveying applications, except when worldwide referencecontrol is established.5-2. Absolute Positioning. Absolute positioning is the most commonly used military and civilapplication of NAVSTAR GPS for real-time navigation. When operating in this passive, real-timenavigation mode, a single receiver, placed at a point where a position is desired, can observe ranges toNAVSTAR GPS satellites. This receiver may be positioned to be stationary (static) over a point or inmotion (kinematic), such as on a vehicle, aircraft, missile, or backpack. Two levels of absolutepositioningaccuracy may be obtained from the NAVSTAR GPS--SPS and PPS. With certainspecialized GPS receiving equipment, data-processing refinements, long-term static observations, andabsolute positional coordinates can be determined to accuracy levels of less than one meter. Theseapplications are usually limited to worldwide geodetic reference surveys.5-3. Differential Positioning. Differential positioning is a process of measuring the differences incoordinates between two receiver points, each of which is simultaneously observing or measuringsatellite code ranges and carrier phases from the NAVSTAR GPS constellation. The process measuresthe difference in ranges between the satellites and two or more ground observing points. The rangemeasurement is performed by a phase-difference comparison, using the carrier phase or the code phase.The basic principle is that the absolute-positioning errors at the two receiver points will be about thesame for a given instant. The resultant accuracy of these coordinate differences is at the meter level forcode phase observations and at the centimeter level for carrier phase tracking. These coordinatedifferences are usually expressed as 3D baseline vectors, which are comparable to conventional surveyazimuth and distance measurements. DGPS positioning can be performed in either a static mode or akinematic mode.5-4. System Configuration. The NAVSTAR GPS consists of three distinct segments--the spacesegment (satellites), the control segment (ground tracking and monitoring stations), and the user segment(air-, land-, and sea-based receivers).EN0593 5-2
a. Space Segment. The space segment consists of all GPS satellites in orbit. The first generation ofsatellites was the Block I or developmental. Several of these are still operational. A full constellation ofBlock II or production satellites is now in orbit. The full constellation consists of 24 Block IIoperational satellites (21 primary with 3 active on-orbit spares). There are four satellites in each of sixorbital planes inclined at 55° to the equator. The satellites are at altitudes of 10,898 nautical miles andhave 11-hour, 56-minute orbital periods. The three active spares are transparent to the user on theground. The user is not able to tell which are operational satellites and which are spares. A procurementaction for Block IIR (replacement) satellites is underway to ensure full system performance through theyear 2025.b. Control Segment. The control segment consists of five tracking stations located throughout theworld (Hawaii, Colorado, Ascension Island, Diego Garcia, and Kwajalein). The information obtainedfrom tracking the satellites is used in controlling the satellites and predicting their orbits. Three of thestations (Ascension Island, Diego Garcia, and Kwajalein) are used for transmitting information back tothe satellites. The master control station is located at Colorado Springs, Colorado. All data from thetracking stations are transmitted to the master control station where they are processed and analyzed.Ephemerides, clock corrections, and other message data are then transmitted back to the three stationsresponsible for subsequent transmittal back to the satellites. The master control station is alsoresponsible for the daily management and control of the GPS satellites and the overall control segment.c. User Segment. The user segment represents the ground-based receiver units that process thesatellite signals and arrive at a user position. This segment consists of both military and civil activitiesfor an almost unlimited number of applications in a variety of air-, land-, or sea-based platforms.5-5. Broadcast Frequencies and Codes. Each NAVSTAR satellite transmits signals on two L-bandfrequencies, designated as L1 and L2. The L1 carrier frequency is 1575.42 megahertz and has awavelength of about 19 centimeters. The L2 carrier frequency is 1227.60 megahertz and has awavelength of about 24 centimeters. The L1 signal is modulated with a precision code (P-code) and acoarse-acquisition code (C/A-code). The L2 signal is modulated with only the P-code. Each satellitecarries precise atomic clocks to generate the timing information needed for precise positioning. Anavigation message is transmitted on both frequencies and contains ephemerides, clock corrections andcoefficients, satellite health and status information, almanacs of all GPS satellites, and other generalinformation.5-6. Pseudorandom Noise Codes. The modulated C/A- and P-codes are referred to as PRN codes.These PRN codes are actually a sequence of very precise time marks that permit the ground receivers tocompare and compute the time of transmission between the satellite and the ground station. The rangeto the satellite can be derived from this transmission time. This is the basis behind GPS rangemeasurements. The C/A-code pulse intervals are about every 300 meters. The more accurate P-codepulse intervals are every 30 meters.5-3 EN0593
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SUBCOURSEEN0593EDITIONAUNITED STATE
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TERMINAL LEARNING OBJECTIVE:ACTION:
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Part G: Adjusting Precise-Positioni
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PART A - FIGURES OF THE EARTH1-1. T
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Figure 1-2. Flattening Fractiona. T
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1-3. Geoid. In geodesy, precise com
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point in the survey to provide the
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one side of a triangle and all of t
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Figure 1-10. Simple Triangulation N
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observation, contains a light sourc
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of a horizontal rod with a small sp
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The Airy theory, announced by G. B.
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Figure 1-15. Products of the Gravim
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a. If the shape of the earth was ex
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Figure 1-16. Single Astronomic Stat
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Figure 1-17. Astro-Geodetic Deflect
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Figure 1-19. Astro-Geodetic Datum O
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(c) The significance of a gravity-o
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absolute deflections of the vertica
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Figure 1-23. Preferred Datumsa. The
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1-17. The World Geodetic System. Be
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Figure 1-25. Using the Same Referen
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LESSON 1PRACTICE EXERCISEThe follow
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12. Which of the following is assum
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LESSON 1PRACTICE EXERCISEANSWER KEY
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THIS PAGE IS INTENTIONALLY LEFT BLA
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for all military and civilian activ
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i. Additional support for other top
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2-7. Status. At present, topographi
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in both. (North American Datum of 1
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water can impede leveling operation
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A field recording booklet. A single
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PART I - OFFICE WORK2-24. General.
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PART J - SURVEY COMMUNICATION2-28.
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length or side is known, and all th
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second-order, Class I net. The leng
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The number of observations required
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to perform the reconnaissance. Fail
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and cultivated, or fields may have
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e an alphanumeric symbol that is st
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2-53. Intervisibility of Stations.
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station is (K/2) 2 x 0.0676, or one
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Figure 2-8. Similar Triangles Solut
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2-54. Height of Obstructions. It is
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authorized to change the name, it s
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Figure 2-12. Cells Connected in Par
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added as the cells weaken. Three un
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Figure 2-16. Construction Details f
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2-60. Wooden Towers. When it become
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11. The face of the 5-inch signal l
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average line in a triangulation sys
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3-4. Slope Measurements. The slope
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strip as close as possible to its f
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. Sight along the tops of both of t
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Column 1. Record the station number
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stake to steady it. With the back o
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Figure 3-3. DA Form 4446 (Sample of
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micrometer in this optical system i
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laterally across the front of the e
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Figure 3-7. Horizontal Circle and M
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out of adjustment. If the index mar
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(1) In order to avoid instrumental
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location of the vertical circle on
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Figure 3-13. Open Traversec. Closed
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designate the exact point of refere
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Page 140 and 141: When adjusting a traverse that star
Page 142 and 143: LESSON 3PRACTICE EXERCISEThe follow
Page 144 and 145: 11. The unit of graduation on a hor
Page 146 and 147: LESSON 3PRACTICE EXERCISEANSWER KEY
Page 148 and 149: THIS PAGE IS INTENTIONALLY LEFT BLA
Page 150 and 151: differential leveling. The theodoli
Page 152 and 153: additional runs are made due to exc
Page 154 and 155: Figure 4-2. Wild N-3 Precision Leve
Page 156 and 157: (8) Loosen the azimuth clamp (13),
Page 158 and 159: 4.7. Miscellaneous Equipment. In ad
Page 160 and 161: (2) To check for gross errors in th
Page 162 and 163: (a) (1) Begin by completing the inf
Page 164 and 165: Set up and level the instrument. Re
Page 166 and 167: Figure 4-8. Sun and Wind Code(5) Th
Page 168 and 169: (10) Enter the interval between the
Page 170 and 171: Figure 4-9. Closed-Circuit River Cr
Page 172 and 173: Figure 4-11. Sample DA Form 5820 (R
Page 174 and 175: is 0. When the telescope is pointed
Page 176 and 177: stations. However, since all statio
Page 178 and 179: a. Complete the heading, as shown.b
Page 180 and 181: a. (1) Enter the date, as in the sa
Page 182 and 183: LESSON 4PRACTICE EXERCISEThe follow
Page 184 and 185: 11. The maximum length of site to o
Page 186 and 187: LESSON 4PRACTICE EXERCISEANSWER KEY
Page 190 and 191: 5-7. Pseudorange. A pseudorange is
Page 192 and 193: 5-15. Number of Pseudorange Observa
Page 194 and 195: i. Probable Error Measures. The acc
Page 196 and 197: Table 5-1. Representative GPS Error
Page 198 and 199: Table 5-2. Carrier Phase Trackinga.
Page 200 and 201: exercise extreme caution in applyin
Page 202 and 203: not be designed or performed to ach
Page 204 and 205: Table 5-3. GPS-S Design, Geometry,
Page 206 and 207: f. Multiple/Repeat Baseline Connect
Page 208 and 209: possible ionospheric and tropospher
Page 210 and 211: Figures 5-4. PDOP Versus Time PlotP
Page 212 and 213: e. Field Processing and Verificatio
Page 214 and 215: All carrier phase relative-surveyin
Page 216 and 217: time spent and the cost of conducti
Page 218 and 219: movement between occupation sites,
Page 220 and 221: 5-37. General. GPS baseline solutio
Page 222 and 223: (1) Receiver Time. This technique u
Page 224 and 225: NOTE: Repeated baselines should be
Page 226 and 227: 5-43. Loop Closure Checks. Postproc
Page 228 and 229: necessary to determine approximate
Page 230 and 231: This will ensure that future work w
Page 232 and 233: may (and usually does) far exceed t
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Page 236 and 237: i. Relative GPS baseline standard e
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12. When the networking method is s
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THIS PAGE IS INTENTIONALLY LEFT BLA
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FAR-77 obstructions. Aircraft-movem
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Figure 6-1. Imaginary SurfacesEN059
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Figure 6-3. Approach Surfacesa. Fed
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. Federal Aviation Regulation-77, S
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Table 6-4. Airport Obstruction Accu
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A horizontal scale of 1:12,000 and
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Figure 6-4. Sample DA Form 5821 (Ai
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Figure 6-5. Sample DA Form 5822 (PA
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