GE-109 Satellite Geodesy Topic 7 PDF

GE 109 – Satellite Geodesy Topic 7: GNSS Positioning Modes (Static, PPK and RTK) and Guidelines and Specifications for Land Surveys Lecturer: Engr. Jaymond T. Verzosa Department of Geodetic Engineering College of Engineering and Geosciences Caraga State University Authors/Contributors* This mat...

GE 109 – Satellite Geodesy Topic 7: GNSS Positioning Modes (Static, PPK and RTK) and Guidelines and Specifications for Land Surveys Lecturer: Engr. Jaymond T. Verzosa Department of Geodetic Engineering College of Engineering and Geosciences Caraga State University Authors/Contributors* This material was prepared/contributed by the following faculty members: Name Type of Contribution Date of Contribution/Revision Engr. Jojene R. Santillan Established (first version) 11/15/2018 Engr. Joy C. Casinginan Standardized the format 10/18/2019 Engr. Jojene R. Santillan Edited, updated and proofread 10/24/2019 the contents Engr. Kendel P. Bolanio Updated the format 09/25/2021 *If this material was edited, revised or updated, kindly fill-up the table with required details accordingly. Copyright Notice Copyright © 2020-2021 by All Authors/Contributors and Department of Geodetic Engineering, College of Engineering and Geosciences, Caraga State University, Butuan City. All rights reserved. Unless otherwise indicated, all materials on these module are copyrighted by the entities indicated above. No part of this module maybe reproduced, stored in a retrieval system, or transmitted in any form or by any means, without either the prior written permission or authorization of Authors/Contributors and the Department of Geodetic Engineering, College of Engineering and Geo-Sciences, Caraga State University, Butuan City. IMPORTANT: The PowerPoint file shall never be distributed to other parties (including students). Only a PDF of this file shall be distributed to students of the course only. Distribution of the PDF to other parties except students should have prior permission or authorization of Authors/Contributors and the DGE of CEGS, CSU. Presentation Outline GNSS Positioning Modes Guidelines and Specifications for Land Surveys ▪ Control Survey Accuracy Specifications according to DAO 2007-29 ▪ Selected Provisions of DMC 2010-13 related to GNSS-based surveys ▪ LMC No. 2015-01 (Guidelines on the use of RTK GNSS in the conduct of all kinds of lot surveys with tertiary accuracy) Expected Outcomes At the end of this lecture, the students would be able to: Understand the concepts behind the two ways of GNSS positioning; Understand the concepts and the differences behind different modes of relative GNSS positioning; Apply the different modes of relative GNSS positioning in their line of work; Understand the different provisions of DAO 2007-29, DMC 2010-13 and LMC 2015-01, and their importance in conducting GNSS based land surveys; and Apply or adhere to the different provisions of DAO 2007-29, DMC 2010-13 and LMC 2015-01 in conducting GNSS based land surveys. Part 1 GNSS Positioning Modes Guidelines and Specifications for Land Surveys ▪ Control Survey Accuracy Specifications according to DAO 2007-29 ▪ Selected Provisions of DMC 2010-13 related to GNSS-based surveys ▪ LMC No. 2015-01 (Guidelines on the use of RTK GNSS in the conduct of all kinds of lot surveys with tertiary accuracy) Two Ways of GNSS Positioning Point Positioning ▪ can be absolute (APP) or precise (PPP) Relative Positioning October 4, 1957 Source: https://www.xyht.com/wp-content/uploads/2015/03/Sept_2013_12.jpg Two Ways of GNSS Positioning Point Positioning ▪ Employs one receiver that calculates (pseudo)ranges from the satellites to determine the user’s position instantaneously as long as 4 or more satellites are visible at the receiver ▪ Used mainly when a relatively low accuracy is required ▪ Examples: o Handheld GNSS receivers o GNSS receivers in mobile phones October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Two Ways of GNSS Positioning Relative Positioning ▪ Employs two receivers simultaneously tracking the same satellites (at least 4 satellites) o One receiver has known position o The other receiver(s) has unknown position(s) ▪ Code based or carrier phase measurements can be used ▪ Used for high accuracy applications such as surveying and mapping, GIS, and precise navigation ▪ Utilizes or applies the following positioning techniques: o DGNSS o RTK October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Relative GNSS Positioning/Surveying Modes Static Requires post-processing of GNSS raw data for Fast (Rapid) Static application of differential corrections and precise Stop and Go positioning calculations Kinematic RTK Real-Time DGNSS October 4, 1957 Static GNSS Surveying The observation, or occupation, time varies from about 20 minutes to a few hours, depending on: ▪ the distance between the base and the remote receivers (i.e., the baseline length) ▪ the number of visible satellites, and the satellite geometry. The measurements are usually taken at a recording interval of 10, 15, or 20 seconds ▪ instrument height also needs to be measured “Base” October 4, 1957 “Rover” Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Static GNSS Surveying After completing the field measurements, the collected data is downloaded from the receivers into the PC for processing using a GNSS Post processing software ▪ In some cases, the raw GNSS file needs to be converted first into a universal format called the RINEX format ▪ RINEX – Receiver Independent Exchange Format o standard format that allows the management and disposal of the measures generated by a receiver, as well as their off line processing by a multitude of applications, whatever the manufacturer of both the receiver and the computer application “Base” October 4, 1957 “Rover” Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Example RINEX GNSS Observation File October 4, 1957 Static GNSS Surveying In post processing, the GNSS data for both the base and rover is loaded ▪ for each point, the following is required: o observation data file o navigation data file (containing satellite ephemerides and other information about the satellites) ▪ if available, a meteorological data file can be used for tropospheric correction October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Static GNSS Surveying The base stations is set as a control point and its known coordinates is entered Baseline processing and network adjustment is then performed to compute the baseline length and orientation and to calculate the coordinates of the unknown (rover) points October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Example RINEX GNSS Navigation Data/Message File (for GPS Satellites) October 4, 1957 Example RINEX GNSS Navigation Data/Message File (for GLONASS Satellites) October 4, 1957 Example RINEX GNSS Navigation Data/Message File (for BDS Satellites) October 4, 1957 Example Baseline Processing October 4, 1957 Processed Baselines and Calculated Coordinates October 4, 1957 Fast (Rapid) Static GNSS Surveying Employs two or more receivers simultaneously tracking the same satellites. Only the base receiver remains stationary over the known point during the entire observation session The rover receiver remains stationary over the unknown point for a short period of time only, and then moves to another point whose coordinates are sought Similar to the static GPS surveying, data recorded by the base and rover receivers must be downloaded and post processed to calculate the position of unknown points October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Stop-and-Go GNSS Surveying Also employs two or more receivers simultaneously tracking the same satellites ▪ a base receiver that remains stationary over the known point ▪ one or more rover receivers The rover receiver travels between the unknown points, and makes a brief stop at each point to collect the GNSS data. ▪ The data is usually collected at a 1 to 2 second recording rate for a period of about 30 seconds per each stop. October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Stop-and-Go GNSS Surveying This method is suitable when the survey involves a large number of unknown points located in the vicinity (i.e., within up to 10 15 km) of a known point. Also requires post processing to calculate the coordinates of unknown points October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Kinematic GNSS Surveying Also employs two or more receivers simultaneously tracking the same satellites ▪ a base receiver that remains stationary over the known point ▪ one or more rover receivers that are moving over unknown points The rover receiver travels over unknown points BUT DO NOT STOP Also requires post processing to calculate the coordinates of unknown points October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ Kinematic GNSS Surveying Less accurate than stop and go surveying ▪ The positional accuracy is expected to be higher with the stop and go surveying, as the errors are averaged out when the receiver stops at the unknown points October 4, 1957 Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ RTK GNSS Surveying The base receiver remains stationary over the known point and is attached to a radio transmitter Similar to the conventional kinematic GNSS method ▪ a data rate as high as 1 Hz (one sample per second) is required. The base receiver measurements and coordinates are transmitted to the rover receiver through the communication (radio) link The built in software in a rover receiver combines and processes the GNSS measurements collected at both the base and the rover receivers to obtain the rover Source: https://lasersurveyingequipment.com.au/wp-content/uploads/2019/07/GPS2.gif coordinates. Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ RTK GNSS Surveying This method is suitable when: ▪ the survey involves a large number of unknown points located in the vicinity (i.e., within up to about 10- 15 km) of a known point ▪ the coordinates of the unknown points are required in real time ▪ the line of sight, the propagation path, is relatively unobstructed Text Source: http://what-when-how.com/gps/gps-positioning-modes-part-1/ PPK Surveying PPK stands for Post Processed Kinematic ▪ Generally used for mapping or for surveying points where only several cm of precision are needed, such as o Mapping out a feature such as a fault scarp or a shoreline; o Recording the locations of sample sites; or o Measuring the positions of markers such a stakes on a glacier to determine ice velocities ▪ Data must be post processed to achieve high precision results; this requires a processing software Text source: https://kb.unavco.org/kb/print-618.html Image source: https://www.questuav.com/industries/surveying/attachment/ppk_setup_edited/ PPK Surveying PPK surveys require data from at least two receivers: ▪ A ‘base’ (reference) receiver; and ▪ A ‘rover’ (moving) receiver. You may use as many rover receivers as you wish. If you have access to raw data from a reference station already operating at an appropriate sample rate in your area (within 10 km of your survey), there is no need to set up an additional base station; ▪ note that the logging rate at the base, however, must be at least as high as the desired survey rate. Text source: https://kb.unavco.org/kb/print-618.html Image source: https://www.questuav.com/industries/surveying/attachment/ppk_setup_edited/ PPK Surveying There are two types of survey in PPK surveys: ▪ Topo points survey are short (usually 15 second) occupations (e.g., over a sample site or survey marker) ▪ Continuous survey mode allows ongoing collection at a specified logging interval (e.g., every 5 seconds) o used for mapping Text source: https://kb.unavco.org/kb/print-618.html Image source: https://www.questuav.com/industries/surveying/attachment/ppk_setup_edited/ Real-time DGNSS a code based relative positioning technique that employs two or more receivers simultaneously tracking the same satellites It is used when a real time meter- level positioning is required. The method is based on the fact that the GNSS errors in the measured pseudoranges are essentially the same at both the base and the rover, as long as the baseline length is within a few hundred kilometers. Text source: https://kb.unavco.org/kb/print-618.html Image source: https://www.questuav.com/industries/surveying/attachment/ppk_setup_edited/ Part 2.1 GNSS Positioning Modes Guidelines and Specifications for Land Surveys ▪ Control Survey Accuracy Specifications according to DAO 2007-29 ▪ Selected Provisions of DMC 2010-13 related to GNSS-based surveys ▪ LMC No. 2015-01 (Guidelines on the use of RTK GNSS in the conduct of all kinds of lot surveys with tertiary accuracy) Control Point Establishment using GNSS Methods in the Philippines Specifications and procedures for CP establishment in the Philippines is governed by: ▪ DAO 2007-29 (Revised Regulations on Land ▪ DMC 2010-13 (Adoption of the Manual on Land Survey Procedures) o Articles 1 2, Articles 16 17, Articles 25 26 o Annexes III, XX Text source: https://kb.unavco.org/kb/print-618.html Image source: https://www.questuav.com/industries/surveying/attachment/ppk_setup_edited/ Control Survey Accuracy Specifications Geodetic Control Surveys Source: DENR, 2007. Revised Regulations on Land Surveys, DENR Administrative Order No. 2007-29. Control Survey Accuracy Specifications Project Control Surveys Source: DENR, 2007. Revised Regulations on Land Surveys, DENR Administrative Order No. 2007-29. Control Survey Accuracy Specifications For complete details: DENR, 2007. Revised Regulations on Land Surveys, DENR Administrative Order No. 2007-29. Available online at: https://server2.denr.gov.ph/uploads/rmdd/dao-2007-29_180.pdf Part 2.2 GNSS Positioning Modes Guidelines and Specifications for Land Surveys ▪ Control Survey Accuracy Specifications according to DAO 2007-29 ▪ Selected Provisions of DMC 2010-13 related to GNSS-based surveys ▪ LMC No. 2015-01 (Guidelines on the use of RTK GNSS in the conduct of all kinds of lot surveys with tertiary accuracy) Selected Provisions of DMC 2010-13, esp. those related to GNSS Article 1, Section 2: ▪ All Geodetic Control Surveys shall be conducted in the Philippine Reference System of 1992 (PRS 92) using survey grade GNSS receivers Section 9, On Maximum Baseline Length: ▪ Primary Geodetic Network o 1st order: 50 km o 2nd order: 25 km ▪ Secondary Geodetic Network o 3rd order: 5 km o 4th order: variable (each barangay shall have at least a pair of Control Points not more than 2 km apart) Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 10. Designing Network of Controls ▪ intervisibility of station are not necessary in order to have a good Network Geometry in the GNSS observation ▪ However, in the preparation of Network Design, it is necessary that points selected can be occupied, located in a stable ground and shall not be affected by any construction activities in the near future ▪ Swampy or loose soil areas should be avoided Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 11, on factors to consider in Network Design: The terrain and the physiographic features of the project area The availability of old Geodetic Controls Number of GNSS Receivers. More than Three (3) Receivers are sufficient for the purpose. Appropriate number and length of observations These are dependent on the type of receivers (single or dual) to be used and the purpose of the survey >> See Section 25 for other details. Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 13, on conditions that the Network Design shall conform to: ▪ The lines connecting the control points within the network should create closed polygons with the minimum number of sides, such as triangles that will create a rigid network. ▪ The Network shall be designed so that all stations or points included therein have at least three (3) known PRS 92 control points. ▪ The designed Network should have an adequate amount of Redundancy, or additional measurement over and beyond the absolute minimum required considering that the main objective is to have a required precision of the control point’s final coordinates. o As such, an optimal number of known points should be included, with as many cross ties and repeated measurements as possible. ▪ Schedules for the field observation shall also be included in the plan. o The field observations shall be timed when the Position Dilution of Precision (PDOP) is low. o A low PDOP value indicates a higher probability of accuracy. Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 14: ▪ Reconnaissance of the area shall be conducted to determine if there are control points that need to be transferred from their proposed sites to strengthen weak geometric figures. ▪ The result of the Reconnaissance shall finalize the preliminary Network Design. ▪ During the reconnaissance, the following shall be determined o (d) Proximity of radio station towers that may possibly disrupt transmission of data and presence of any obstructions above 15° of the horizon; Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 15: Geodetic Control Monuments Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 19: ▪ The establishment of geodetic control covering the 1st and 2nd Order Accuracy shall be done using a GNSS Receiver ▪ There shall be at least 3 receiver units per survey team ▪ The employment of more than 4 Receivers is preferable Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 20: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 22: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 23: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 23: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 23: Annex XX Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 24: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 24: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 24: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 25: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 26: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 27: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 166: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 186: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 186: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 186: Selected Provisions of DMC 2010-13, esp. those related to GNSS Section 186: Selected Provisions of DMC 2010-13, esp. those related to GNSS For complete details: DENR, 2010. Adoption of the Manual on Land Survey Procedures, DENR Memorandum Circular No. 2010-13. Available online: https://server2.denr.gov.ph/uploads/rmdd/dmc-2010-13_111.pdf Part 2.3 GNSS Positioning Modes Guidelines and Specifications for Land Surveys ▪ Control Survey Accuracy Specifications according to DAO 2007-29 ▪ Selected Provisions of DMC 2010-13 related to GNSS-based surveys ▪ LMC No. 2015-01 (Guidelines on the use of RTK GNSS in the conduct of all kinds of lot surveys with tertiary accuracy) Section 1. Registration of Receivers Before GEs can use RTK GNSS in the conduct of land surveys, RTK GNSS receivers shall be first registered pursuant to Section 22, DAO 2007-29. Section 2. Procedures and Conditions for the Use of RTK GNSS (1) Only Dual Frequency Receivers with pertinent specifications as stated in Section 202(g) of the DMC 2010-13 shall be used. Basic setup: ▪ One GNSS receiver as a base station ▪ At least one rover GNSS receiver Base receiver shall be located on a point with known WGS-84 coordinate. ▪ the point has unobstructed view of the sky ▪ horizon clearance: at least 15° in all directions! Section 2. Procedures and Conditions for the Use of RTK GNSS (2) The rover RTK GNSS receiver shall be mounted on a range pole and supported by a bipod ▪ helps avoid unnecessary movement of the instrument as in the case when it is hand held Section 2. Procedures and Conditions for the Use of RTK GNSS (2) In the conduct of land survey, the procedures in Sections 20- 27 of DMC 2010-13 shall be followed. The following conditions must be present: ▪ The lot to be subjected to survey shall be located in an open field wherein all corners shall have a horizon clearance of at least 15° in all directions Section 2. Procedures and Conditions for the Use of RTK GNSS (2) In the conduct of land survey, the procedures in Sections 20- 27 of DMC 2010-13 shall be followed. The following conditions must be present: ▪ The lot to be subjected to survey shall be located in an open field wherein all corners shall have a horizon clearance of at least 15° in all directions Section 2. Procedures and Conditions for the Use of RTK GNSS (2) Electronic Total Station (ETS) shall be used in the following ground situations to augment the RTK: ▪ Lot corners that are surrounded by buildings and other structures wherein the 15° horizon clearance is not met ▪ Lot corners that are surrounded by deciduous trees with thick canopy ▪ Lot corners that coincide with the corner of an existing concrete fence ▪ Lot corners that coincide with the building wall ▪ Lot corners located beneath a 20 meter radius of a high voltage power transmission line and other communication facilities Section 2. Procedures and Conditions for the Use of RTK GNSS (2) Electronic Total Station (ETS) shall be used in the following ground situations to augment the RTK: ▪ Lot corners that are surrounded by buildings and other structures wherein the 15° horizon clearance is not met ▪ Lot corners that are surrounded by deciduous trees with thick canopy ▪ Lot corners that coincide with the corner of an existing concrete fence ▪ Lot corners that coincide with the building wall ▪ Lot corners located beneath a 20 meter radius of a high voltage power transmission line and other communication facilities Other important guidelines: Root Mean Square (RMS) value of the station/location during RTK GNSS observation should be 35 or below RMS (Root Mean Square) is the solution RMS for the carrier phase observation, in millicycles of GNSS signal wavelength For example, for L1 carrier phase measurement: the RMS = 35 means 35 millicycles of L1 wavelength » L1 wavelength is 0.19 m » So, RMS in meters = (35/1000)*0.19 = 6.65 mm RTK observation time allotted for each lot corner shall not be less than two (2) minutes. At least 5 satellites tracked with good geometry (i.e., good DOP) Other important guidelines: The RTK rover received shall always be initialized prior to start of data collection ▪ must maintain lock to satellites and to base station radio signal while transferring from one station/location to another A baseline with intervisible ends and a length of at least 200 meters but not more than one (1) kilometer shall be established using the RTK instrument within the vicinity preferably not more than one (1) kilometer from the lot ▪ Distance from the RTK observation shall be compared with the distance using the ETS o difference shall not be more than one (1) centimeter for every 50 meters or 20 centimeters for every one kilometer LMC No. 2015-01 For complete details: LMB, 2015. Guidelines on the Use of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) in the Conduct of All Kinds of Lot Surveys with Tertiary Accuracy, LMB Memorandum Circular No. 2015- 001.  Questions? Department of Geodetic Engineering College of Engineering and Geosciences Caraga State University, Ampayon, Butuan City