My Rtk Net

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 MyRTKnet Concept MyRTKnet Configuration

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

2

East Malaysia Primary GPS Network

Malaysia Active GPS System (MASS Network)

3

IGS Connection

SHAO

LHAS KUNM

WUHN

PIMO

IISC

NTUS

BAKO

COCO KARR

GUAM

MASS DATA ON THE WEB

BAKO – Bakosurtonal, Indonesia COCO – Cocos Island, Australia GUAM – Guam Island, USA IISC – Indian Institute of Science KARR – Karratha, Australia KUNM – Kunming, China LHAS – Lhasa, Tibet NTUS – NTU, Singapore PIMO – Mine and Geoscience Bureau, Philippine SHAO – Shanghai Observatory, China WUHN – 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) 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 (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 surveys.

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

MyRTKnet - 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

MyRTKnet Concept

Geodetic Infrastructure for GNSS Realtime Positioning Reference Frame and Coordinates System – GDM2000 Monitoring of Tectonic Movement Geodynamic Studies


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 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 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 will accept the 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“ corrected“ RTCM realreal time data VRS Rover surveys as in „normal“ 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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Peninsular Malaysia MyRTKnet

East Malaysia MyRTKnet

7.00

UUMK ARAU

6.50

KUDA

7

LGKW GETI TOKA

KBE L

6.00

PASP

SIK1

UMSS

AYER

SGP T 5.50

USMP

6

SETI

KRAI

GRIK

KUAL

BABH

LAB1

TERI LASA

5.00

GMUS

JAMB

RANA

SAND

BEAU KENI TENO

LAHA TUNK

LIMB LAWA

5

Latitude

CAME

PUPK

LIPI

CENE

TLKI

4.00 SBKB

Latitude (N)

MUKH PUSI

4.50

JRNT BEHR SRIJ BENT

MERU BANT

BAHA P DIC

MARU

MUKA

JUML

SIBU MERS GAJA

2

AMAN TEBE

1

JHJY KUKP

TGPG

110 100.00

100.50

1 01.00

101.50

102.00

Longitude

102.50

103.00

103.5 0

KAPI

UMAS

SPGR

1.50

99.50

BELA

SEMA

TGRH

PRTS

2.00

99.00

BINT

KRO M SEG1

2.50

TAWA

4

3

MUAD

UP MS K LAW

3.00

LSEM

PEKN

TLOH

3.50

SEMP

MIRI

104.00

104.50

111

112

113

114

115

116

117

118

119

105.00

Longitude (E)

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Reference Station Setup

MyRTKnet System Setup

²

²

²

²

²

²

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Reference Stations Components

Reference Stations Set-up

Cisco 1721 router Dlink 5port Switch 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 for 48 hours back up power Micromate RS2888 Auto Restart System Lightning protection Moxa 5410 terminal server (27 stations)

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Types of Monument

Reference Station (Jerantut)

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Reference Station (Bukit Pak Apil)

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``

Ethernet Link``

VRS Secondary Server Functions: - Win 2003 Srv OS - VRS application - UPS Service

VRS Prim ary Server Functions: - Win 2003 Srv OS - VRS application & VRS Registry Mirror - UPS Service

Distributed to both VRS Servers

Communication Protocol

Ethernet Link``

GPStream Server Functions: - Win 2003 Srv OS - Splitter and Line Relay

3Com 24 port Gigabit Sw itch Maintenance & Archiving Server Functions: - Win 2003 Srv OS - Base Station physical status monitor - connectivity check to all base stations - RINEX file recovery in event of communications failure - Running UPS Service - Internal HP DLT Tape Backup - Access server accouning

Cisco 3745 Router

1Mbps lease line with ISDN backup

RTK*NET (IP VPN)

64K leased line with ISDN backup

RT K Base Station

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Basic Requirement for Rover GPS Receiver with FW and controller supporting VRS RTK corrections Data Logger which run 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 to serial 3 of the 5700 and the cell phone connected to the second serial port of the PDA.

z

F1

F2

F3

N e xt

But how does this work?

F4

F5

Es c

Menu

En t er

7 4

8 5

1 + /-

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

T

Reference station data streams into the GITN IP cloud via 64K leased lines.

T T

From the GITN cloud, all reference station data is immediately sent to Seksyen Geodesi KL over a 1M leased line. T

Coverage in Peninsular Malaysia

Remote users connect by getting onto the internet using GPRS or GSM to ISP and selecting the IP address of the GITN Internet Gateway 202.75.44.154 port 8080.

T

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 of Trimble

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Coverage in Sabah & Sarawak

MyRTKnet Area Coverage

Malaysia RTK GPS Network System (MyRTKnet) Kudat 30 km Radius Existing MyRTKnet Station 30 km Radius New MyRTKnet Station (2006) 30 km Radius New MyRTKnet Station (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 Datu Tawau Semporna

Within the Peninsular Malaysia RTK Net and Densed Network in Sabah and Sarawak 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 and Sarawak, DGPS Net will be operational

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Services Provide 5 difference services for users in Peninsular Malaysia 95% Network RTK coverage - VRS 95% Single Base RTK coverage 95% Post-process Virtual Rinex Data coverage Provide Single Base RTK service for all reference stations in Sabah and Sarawak Provide Rinex Data for all reference stations

Accuracy VRS and Single Base RTK ± 3 cm

DGPS coverage ± 20 - 50 cm

Post-process Virtual 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 Photogrammetric Control Surveys

Application GIS Applications Control surveys for monumentation Wetland Location Surveys Soil Location Survey Flagging Clearing Limits Tree Surveys Mapping and Navigation

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