cET 318 h国Lce 3.3 Field Reconnaissance 3. 4 Monumentation 7. Field Surveying with GPS 3.5 Organizational design Book:p.133-179 Dr Guoqing Zhou This is a Geodetic Control Test Field located at L Radial Surveying( Cartwheel): Madison County, Central Ohio. lial Surveys: one receiver at a fixed 2 Madison County High Altitude Test Range site, and measuring lines from this fixed 米 planning this type of survey exce that points in close proximity should be connected by direct observation Survey at Different Times: the Example: error between the two points could error in the points Error would not be tolerated rror between the nce it would cause a bad two points would be 0. 14 impression on the whole accuracy. m(relative error of 1: 714) 2. Network Surveying: GPS surveys performed by static(and pseudokinematic) ethods where accuracy is a primary consideration require that observations be performed in a systematic manner and that closed geometric figures be formed to provide closed loops 4. GPS Surveying Procedure An idealized scheme in Fig. 7.5; the basic principles apply for all control netw The Major Points of Network Design The network should consist of closed loops or other geometric figures
1 Dr. Guoqing Zhou 7. Field Surveying with GPS CET 318 Book: p. 133-179 3.3 Field Reconnaissance 3.4 Monumentation 3.5 Organizational Design This is a Geodetic Control Test Field located at Madison County, Central Ohio. 1. Radial Surveying (Cartwheel): Radial Surveys: one receiver at a fixed site, and measuring lines from this fixed site to receivers placed at other locations. A 0.1 m error in the points 2 and 3. Thus, the expected error between the two points would be 0.14 m (relative error of 1:714). No Geometric Consideration for planning this type of survey except that points in close proximity should be connected by direct observation. Survey at Different Times: the error between the two points could be considerable, and Relative Error would not be tolerated since it would cause a bad impression on the whole accuracy. Example: 2. Network Surveying: GPS surveys performed by static (and pseudokinematic) methods where accuracy is a primary consideration require that observations be performed in a systematic manner and that closed geometric figures be formed to provide closed loops. An idealized scheme in Fig. 7.5; the basic principles apply for all control network schemes. The Major Points of Network Design: The network should consist of closed loops or other geometric figures. 4. GPS Surveying Procedure
4.1 Pre-Observation 3. Initialization L Antenna Setup the preprogramming or the on-site input of parameter 2. Receiver Calibration: Self-Calibration: In general, GPs receivers are 3. Minimum number of satellites to track, considered to be self-calibrating and users do not normally 4. Start and stop time for the session, erform equipment calibration 5. Cutoff elevation angle and Zero-Calibration: One simple test is a zero baseline 6. Assignment of a data file name measurement Modern receivers have several channels and track all satellites I. A preselection is necessary to disregard a satellite. 2. The ephemerides are gathered and stored automatically 3. Many receivers have been designed to require the minimum of operator interaction In the kinematic mode, the phase ambiguities are determined 4.2 Observation during initialization by static or kinematic techniques 1. Communications between survey crews are desirable 1. One static technique is based on the occupation of a and generally increase eff resolution after a few observation epock 2. Most static observations can be performed in an 2. Another method is to perform a(rapid) static survey to automated mode so that an operator is not required determine the vector between the fixed point and the However, data checks during the session, and any unknown starting point for the kinematic survey. regularity should be noted in the field log between the fixed point and the starting point. By this 3. In kinematic surveying applications, after determined to millimeter accuracy for short ilia Doints is antenna swap, the vector between the two nitialization, the roving receiver proceeds to the points for which coordinates are desired. As long as four or The kinematic initialization on-the-fly (oTF) is the most more satellites are continuously tracked by both advanced technique to resolve phase ambiguities(more detail in receivers, vectors from the fixed point can be measure Sect. 9.2). to a high degree of accuracy 4.3 Post-Observation 1. At the completion of a session, a check of the antenna position and re-measurement of its height 2. A final site occupation sheet with the following Information: and station name 5. In Situ Data Processing 3. Start and stop times 5. Name of observer 6. Receiver and antenna serial number 7. Height of antenna and eccentricities in position Problems experienced
2 4.1 Pre-Observation 1. Antenna Setup: 2. Receiver Calibration: Self-Calibration: In general, GPS receivers are considered to be self-calibrating and users do not normally perform equipment calibration. Zero-Calibration: One simple test is a zero baseline measurement. 3. Initialization: In static surveying, the initialization of some receivers requires the preprogramming or the on-site input of parameters. 1. Selection of the sampling rate, 2. Bandwidth, 3. Minimum number of satellites to track, 4. Start and stop time for the session, 5. Cutoff elevation angle, and 6. Assignment of a data file name. Modern receivers have several channels and track all satellites 1. A preselection is necessary to disregard a satellite. 2. The ephemerides are gathered and stored automatically. 3. Many receivers have been designed to require the minimum of operator interaction. In the kinematic mode, the phase ambiguities are determined during initialization by static or kinematic techniques. 1. One static technique is based on the occupation of a short, known baseline which allows ambiguity resolution after a few observation epochs. 2. Another method is to perform a (rapid) static survey to determine the vector between the fixed point and the unknown starting point for the kinematic survey. 3. A third static method is to perform an antenna swap between the fixed point and the starting point. By this antenna swap, the vector between the two points is determined to millimeter accuracy for short lines. The kinematic initialization on-the-fly (OTF) is the most advanced technique to resolve phase ambiguities (more detail in Sect. 9.2). 4.2 Observation 1. Communications between survey crews are desirable and generally increase efficiency. 2. Most static observations can be performed in an automated mode so that an operator is not required. However, data checks during the session, and any irregularity should be noted in the field log. 3. In kinematic surveying applications, after initialization, the roving receiver proceeds to the points for which coordinates are desired. As long as four or more satellites are continuously tracked by both receivers, vectors from the fixed point can be measured to a high degree of accuracy. 4.3 Post-Observation 1. At the completion of a session, a check of the antenna position and re-measurement of its height. 2. A final site occupation sheet with the following information: 1. Project and station name 2. Date and session number 3. Start and stop times 4. Station identifier used for file name 5. Name of observer 6. Receiver and antenna serial number 7. Height of antenna and eccentricities in position 8. Meteorological data 9. Problems experienced. 5. In Situ Data Processing
5.1 Data Transfer (Download Data) 5.2 Data processing 1. The First Step in processing is to transfer the data 1. Ouality Control Check: from the receiver to a computer hard disk using 1. at least once per day software provided by the manufacturer. 2. preliminary computations of baseline vectors in the 2. The Main Task in transferring files is to make sure field before leaving the survey area the files are named correctly and the antenna height is 3. The on-site vector processing on daily basis to ensure correct adequate measurements ma 2. Batch File Processing: 3. Most Batch File Processing Software Automatically Today, most of the routine processing is performed by Extracts the antenna height from the site file data batch file processing. All batch files are generated using stored in the receiver. After correcting the names of the three- or four-digit site identification so that the first the various files. one should then check and correct all ask in processing gps data is to ensure that all sites are antenna heights 3. Processing of Static Surveys: 5.3 Trouble Shooting Quality Control 1. Modern processing software uses batch processing to 1. Depends on the computation experience mute baseline vectors 2. Delete the suspected low-quali 2. Once the software has been initiated. the lines are 3. Re-adjust the coordinates of whole network omputed in order, automatically. 4. Repeat the above processing until you find the low-qualify 3. There are two types of processing software: (1)vector by vector and (2)multipoint solutions 5.4 Datum Transformations Horizontal datum. The basic steps are similar for kinematic post 1. Geodetic coordinates are referenced to the values of the fixed processing. The actual difference is the software used control and are on the same datum as the fixed control 2. Much of the newer software is automated 2. Proper ellipsoidal parameters should be used, for examp 3. Main check for kinematic vectors is positions of the NAD-83 GRS-80 oving receiver and check similar values on separate Vertical Datum: See Surveying Courses visits to the same point. 5.5 Computation of Plane Coordinates Software automatically compute all points coordinates Final Report is helpful to others in analyzi 1. Location and project 2. Purpose and the extent 6. Survey Report 3. A description of the monumentation used 4. A description of the instrumentation used 6. The coordinates system employed(Datum) 7. Computation planimetry and height(RMS) 9. Finally, a copy of the original observations (or translated RINEX) should be transmitted as part of the survey
3 5.1 Data Transfer (Download Data) 1. The First Step in processing is to transfer the data from the receiver to a computer hard disk using software provided by the manufacturer. 2. The Main Task in transferring files is to make sure the files are named correctly and the antenna height is correct. 3. Most Batch File Processing Software Automatically Extracts the antenna height from the site file data stored in the receiver. After correcting the names of the various files, one should then check and correct all antenna heights. 5.2 Data Processing 1. Quality Control Check: 1. at least once per day 2. preliminary computations of baseline vectors in the field before leaving the survey area. 3. The on-site vector processing on daily basis to ensure adequate measurements made. 2. Batch File Processing: Today, most of the routine processing is performed by batch file processing. All batch files are generated using the three- or four-digit site identification so that the first task in processing GPS data is to ensure that all sites are properly named. 3. Processing of Static Surveys: 1. Modern processing software uses batch processing to compute baseline vectors. 2. Once the software has been initiated, the lines are computed in order, automatically. 3. There are two types of processing software: (1) vector by vector and (2) multipoint solutions. 4. Processing of Kinematic Surveys : 1. The basic steps are similar for kinematic postprocessing. The actual difference is the software used. 2. Much of the newer software is automated. 3. Main check for kinematic vectors is positions of the roving receiver and check similar values on separate visits to the same point. 5.3 Trouble Shooting & Quality Control 1. Depends on the computation experience 2. Delete the suspected low-quality point 3. Re-adjust the coordinates of whole network 4. Repeat the above processing until you find the low-qualify points. 5.4 Datum Transformations Horizontal Datum: 1. Geodetic coordinates are referenced to the values of the fixed control and are on the same datum as the fixed control. 2. Proper ellipsoidal parameters should be used, for example, NAD-83, GRS-80. Vertical Datum: See Surveying Courses 5.5 Computation of Plane Coordinates Software automatically compute all points coordinates 6. Survey Report A Final Report is helpful to others in analyzing the conduct of a survey. 1. Location and project area 2. Purpose and the extent 3. A description of the monumentation used 4. A description of the instrumentation used 5. The computation scheme (software version) 6. The coordinates system employed (Datum) 7. Computation accuracy in planimetry and height (RMS) 8. All problems encountered should be discussed and equipment failures listed. 9. Finally, a copy of the original observations (or translated RINEX) should be transmitted as part of the survey
Assignment 7 Summary What are the code range and carrier phase GPS survey? 2. What are the static and kinematic GPS surveying 3. What are the relative and differential GPS surveying? What have we learnt? How to transmit the correction data from fixed station to overing station? 5. How does the Sa technology impact the Point positioning DGPS, relative position 6. How to set up the observation window? 7. What does the difference between radial surveys and network surveys? 8. what is zero calibration? How to determine the phase ambiguities in kinematic mode initiation? 10. What should the survey report describe?
4 Summary What have we learnt? Which parts are important? Assignment 7 1. What are the code range and carrier phase GPS survey? 2. What are the static and kinematic GPS surveying? 3. What are the relative and differential GPS surveying? 4. How to transmit the correction data from fixed station to rovering station? 5. How does the SA technology impact the Point positioning, DGPS, relative position? 6. How to set up the observation window? 7. What does the difference between radial surveys and network surveys? 8. What is zero calibration? 9. How to determine the phase ambiguities in kinematic mode of initiation? 10. What should the survey report describe?
