Contents Malaysia Real Time Kinematic GPS Network System
Historical Geodetic Infrastructure of Malaysia The Move to Real-time Application using RTK GPS Limitations of Classical RTK MyRTKne MyR TKnett Con Concep ceptt MyRTKne MyR TKnett Con Config figura uratio tion n
Geodesy Section, Mapping Division Department of Survey and Mapping Malaysia
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Historical Geodetic Infrastructure of Malaysia
Peninsular Malaysia Primary GPS Network
BT68
MRT
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East Malaysia Primary GPS Network
Malaysia Active GPS System (MASS Network)
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IGS Connection
SHAO
LHAS KUNM
WUHN
PIMO
IISC
NTUS
BAKO
COCO KARR
GUAM
MASS DATA ON THE WEB
BAKO – Bakosurto Bakosurtonal, nal, Indonesia COCO – Cocos Island, Australi Australia a GUAM – Guam Island, Island, USA IISC – Indi Indian an Ins Institut titute e of of Scien Science ce KARR – Karratha, Australia Australia KUNM – Kunmin Kunming, g, China LHAS LHA S – Lha Lhasa, sa, Tibe Tibett NTUS – NTU, Singapore Singapore PIMO – Mine and Geo Geoscie science nce Bureau, Philippine SHAO – Shangh Shanghai ai Observatory, Observatory, China WUHN – Wuhan Wuhan,, China KARR – Karratha
GPS
Data available after 24 hours
Post-processing
application
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The Move to Real-time Application using RTK-GPS Classical GPS and kinematic survey ( post-processed) post-processed) can determine the precise position of a roving receiver relative to a stationary station. Classical GPS and kinematic technique requires office procedure/work before coordinate of a station can be derived – time consuming Real time kinematic kinematic (RTK) surveying is the latest dynamic GPS survey technique. RTK-GPS utilize short observation times and enable you to move between station. RTK-GPS can instantly determine the position of a roving unit to centimeter-level accuracy using carrier phase positioning. This technique is ideal for various application such as engineering, cadastral, topographic and detail s urveys.
Limitations of Classical RTK Limited range from single reference station Errors grow with baseline length (ppm) Reliability and performance decrease with distance to the next reference station Dependency on single reference station No integrity monitoring No alarming
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Single Base Station Surveying
MyRTK TKn net - RTK VRS Networking
Two receivers Productivity loss Potential gross error in establishing RS Power supply Communications/radio Dial-in systems: Each reference station uses different number to call
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Objectives of MyRTKnet Geodetic Infrastructure for GNSS Realtime Positioning Reference Frame and Coordinates System Sys tem – GDM GDM200 2000 0 Monitoring of Tectonic Movement Geodynamic Studies
MyRT My RTKn Knet et Co Conc ncep eptt The
use of a network of reference stations instead of a single reference station allows to model the systematic errors in the region and thus provides the possibility of an error reduction. This
allows a user not only to increase the distance at which the rover receiver is located from the reference, it also increases the reliability of the system and reduces the RTK initialization time.
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The network error correction terms can be transmitted to the rover in the following mode: A Virtual Reference station mode as described below. This mode requires bi-directional communication. The basic advantage of this mode is that it makes use of existing RTCM and CMR standards implemented in all major geodetic rover receivers and thus is compatible with existing hardware.
The “Virtual Reference Station” concept is based based on having a network of GPS reference stations continuously connected via data links to a control center. A computer at the control center continuously gathers the information from all receivers, and creates a living database of Regional Area Corrections. These are used to create a Virtual Reference Station, situated only a few meters from where any rover is situated, together with the raw data, which would have come from it. The rover interprets and uses the data just as if it has come from real reference station.
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Implementation Principles of the VRS functional system solution 1. We need a number of reference reference stations (at least three), which are connected to the network server via some communication links. 2. The GPS rover sends its approximate position to the control center that is running GPSNet. It does this by using a mobile phone data link, such as GSM, to send a standard NMEA position string called GGA. 3. The control center center will accept accept the position, position, and responds by sending RTCM correction data to the rover. As soon as it is received, the rover will compute a high quality DGPS solution, and update its position. The rover then sends its new position to the control center.
The network server will now calculate new RTCM corrections so that they appear to be coming from a station right beside the rover. It sends them back out on the mobile phone data link (e.g.GSM). The DGPS solution is accurate to +/-1 meter, which is good enough to ensure that the atmospheric and ephemeris distortions, modeled for the entire reference station network, are applied correctly. This technique of creating raw reference station data for a new, invisible, unoccupied station is what gives the concept its name, “The Virtual Reference Station Concept”
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VRS Data Flow Reference station data streams back to the server via leased lines or LAN/WAN
VRS Data Flow Roving receiver sends its position back to the server VRS position is established
VRS
NMEA
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VRS Data Flow Server uses VRS position to create „corrected “ RTCM realreal-time data VRS
Rover surveys as in „normal “ “ RTK – – but getting VRS data as if from a nearby reference station
RTCM
NMEA
MyRTKnet Configuration Network of 50 dual frequency GNSS referense stations in Peninsular Malaysia Network of 28 dual frequency GNSS reference stations in East Malaysia Control Centre at JUPEM Headquarter
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Reference Station Setup
MyRTKn MyR TKnet et Sy Syste stem m Set Setup up
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Reference Stations Components
Reference Stations Set-up
Cisco 1721 router Dlink Dlin k 5port Switch Switch 10/100Mbps 10/100Mbps Trimble 5700 with Zephyr antenna (27 stations) Trimble NetR5 with Zephyr antenna (51 stations) Advantech Adam 6017 A/D module Micromate Hybrid UPS System System for 48 hours back up power Micromate Micr omate RS2888 Auto Restart Restart System System Lightning protection Moxa 5410 terminal terminal server server (27 stati stations) ons)
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Types of Monument
Reference Station (Jerantut)
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Reference Station (Buk (B ukit it Pa Pak k Api Apil) l)
Reference Station (Port Dickson)
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Reference Station (Tokai)
Reference Station (Arau)
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Reference Station (Behrang)
Control Centre Set-up
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Control Centre Configuration
Control Centre Components Six GPSNet server with hot swap redundancy Two Maintenance servers for system monitoring and data archiving Two WEBROUTER servers for web server and data distribution. 3745 router for access to the Internet and GITN cloud 10/100/1000 switch to interconnect all components UPS to hold the system for power backup
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RTK Control Central Network 19" System Rack
Servers are installed on 19" System Rack
Ethernet Link``
Et hernet Link ``
VRS Secondary Server Functions: - Win 2003 Srv OS - VRS application - UPS Service
VRS Primary Server Functions: - Win 2003 Srv OS - VRS application & VRS Registry Mirror - UPS Service
Distributed to both VRS Servers
Communication Protocol
Et hernet Link ``
GPStream Server Functions: - Win 2003 Srv OS - Splitter and Line Relay
3Com 24 port Gigabit Switch Maintenance & Archiving Server Functions: - Win 2003 Srv OS - Base Station physical status monitor - connectivity check to all base stations - RINEX file recov ery in event of communications failure - Running UPS Service - Internal HPDLT Tape Backup - Access server accouning
Cisco 3745 Router
1Mbps lease line with ISDN backup
RTK*NET (IP VPN)
64K leased line with ISDN backup
RTK Base Station
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Basic Requirement for Rover GPS Receiver with FW and controller supporting VRS RTK corrections Data Logger Logger which which run WindowsCE WindowsCE and supports PPP connections to ISPs or to GPRS – Trimble TSCe / ACU However; if using older Trimble controllers or other third party equipment that do not have NTRIP Support built into the controller, an external PDA or computer is required Mobile Phone with GSM Data / GPRS services
External PDA Connection Here we have a TSC1 connected to serial port 1 of the 5700, a PDA connected serial 3 of connected to serial the 5700 and the cell phone connected to the second serial port of the PDA.
z
F 1 F 2 F3
Next
7 4 1 + /-
But how does this work?
F 4 F 5
Esc
M en u
E n t er
8 5 2 0
9 6 3 .
Ø
The TSC1 instructs the 5700 that it is going to use a RTK VRS type of solution with the radio/corrections source connected to serial port 3. We dial the cell phone to connect to GPRS from the PDA and the PDA runs an application to select the NTRIP source and then to decode the NTRIP formated corrections and output the pure RTCM or CMR to the 5700.
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VRS Data Flow T
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Reference station data streams stre ams into into the theGITN GITN IP cloud via 64K leased lines.
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From the GITN cloud, all reference station data is immediately sent to Seksyen Geodesi KL over a 1M leased line.
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Coverage in Peninsular Malaysia
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Remote users connect by getting onto the internet using GPRS or GSM to ISP and selecting the IP address of the GITN Internet Gateway 202.75.44.154port 8080. 202.75.44.154
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The GITN Internet Gatway forwards requests on port 8080 to the GPStream computer on which the NTRIP server is running.
Other users can also access the wenserver at 202.75.44.154 for access to customizable Rinex files for post processing and other services.
Upon receipt of the NMEA GGA string from the particular user, the system will begin to stream network RTK corrections to the user.
Courtesy of John Serink Serink of Trimble
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Coverage Cove rage in Sabah Sabah & Sarawak Sarawak
MyRTKn MyR TKnet et Are Area a Cover Coverage age
Malaysia RTK GPS Network System (MyRTKnet) Kudat 30 km Radius Existing MyRTKnetStation 30 km Radius New MyRTKnetStation (2006) 30 km Radius New MyRTKnetStation (2007) 30 km Radius MASS Upgrade (2006)
Kota Belud Kota Kinabalu
Jambongan Sandakan
Ranau
Beaufort Labuan
Miri Marudi
Long Seridan Bintulu Mukah Sibu
Belaga
Semantan Kapit
Kuching
Tebedu
Sri Aman
Keningau
Tenom Lawas Long Pa Sia Limbang Long Semado
Tungku Lahat Lahat Datu Tawau Semporna
Within the Peninsular Malaysia RTK Net and Densed Den sed Net Networ work k in Sabah Sabah and Saraw Sarawak ak and and <30 km beyond, Network RTK will be functional Where a reference station exists, within a 30Km range Single Base RTK will be available Throughout the Peninsular Malaysia and parts of Sabah Sabah and Sarawak Sarawak,, DGPS Net Net will be operational
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Services Provide 5 difference services for users in Peninsular Malaysia 95% Network Network RTK RTK coverage coverage - VRS 95% Single Base RTK coverage 95% Post-proces Post-processs Virtual Virtual Rinex Data coverage Provide Single Base RTK service for all reference refer ence station stationss in Sabah and Sarawak Sarawak Provide Rinex Rinex Data for all reference stations
Accuracy VRS and Single Base RTK ±
3 cm
DGPS coverage ±
20 - 50 cm
Post-pro Post -process cess Virtual Virtual Rinex Rinex Data <
±
3 cm
100% DGPS coverage
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Application Engineering Survey Topographic Survey Boundary Survey Construction Staking Utility Extension Survey Flood Survey Study and Analysis Photogramm Photo grammetri etricc Cont Control rol Surveys
Application GIS Applications Control surveys for monumentat monumentation ion Wetland Location Surveys Soil Location Survey Flagging Clearing Limits Tree Surveys Mapping and Navigation
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