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METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 1
METIS Second Master Training & Seminar
Augmentation Systems Available in Egypt
ByEng. Ramadan Salem
M. Sc. Surveying and Geodesy
Email: ramadan_salem@link.net
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 2
The METIS project is managed by the European GNSS Supervisory Authority through Euro-MED GNSS I project
1. GNSS Error Sources2. What Is Augmentation?3. Benefits of Augmentation4. Different Types of Augmentation Systems Available in Egypt5. Comparing Free EGNOS vs. Commercial OmniSTAR VBS
Augmentation Systems Available in Egypt:Plan of the Presentation
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 3
GNSS Error Sources
GNSS Satellites
User’s Receiver Calculates Position
• Errors in calculated position:– Multipath– Ionospheric & Tropospheric Delays– Satellite Clock and Orbit Errors– Receiver Clock and Noise Errors– Selective Availability (S/A) if any (GPS Only).
– Dilution of Precision (DOP)
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 4
User’s Receiver Calculates PositionReference Receiver
Calculates Position
Compares to its own fixed position
Calculates Error
Transmits Corrections
Applies Correction to Calculated position
What Is Augmentation ?
User Receiver
GNSS Satellites
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 5
GPS-LikeSignal
DifferentialCorrections
Use/Don’t UseMessage
+ ACCURACY+ AVAILABILITY+ CONTINUITY
+ Integrity
Benefits of Augmentation
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 6
1. Differential Positioning:A. Post-Mission.B. Real-Time:
i. Local Coverage (RTK)ii. Global Coverage (OmniSTAR VBS & HP).
2. Ground-Based Augmentation System (GBAS)• Pseudolite (Beacons)
3. Space-Based Augmentation System (SBAS)• EGNOS
Augmentation Systems Available in Egypt
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 7
Then data is downloaded to PC
(1-A) Post-Mission Diff. Positioning
Base Receiver(Known Point)
Rover Receiver(Unknown Point)
GNSS SatellitesGNSS Satellites
The software matches the time tags, detects error at base station and subtracts the same error at the same time from the roving file.
The data is collected at the sametime by the 2 receivers having thesame record interval.
Post-ProcessingSoftware
Rover (Unknown)Position
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 8
(1-B) Real-Time Diff. Positioning
Base Receiver(Known Point)
Rover Receiver(Unknown Point)
GNSS SatellitesGNSS Satellites
computes the satellite range corrections
applies the corrections to their measured ranges, using the corrected ranges to compute their position
TelemetryLink
Global(e.g. OmniSTAR)
Global(e.g. OmniSTAR)
Local(e.g. RTK)
Local(e.g. RTK)
Real-Time Corrections
Both Base and Rover observe at least 4 common satellites at the same time
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 9Base Station
Base Radio
Rover Radio Antenna
GPS Antenna
Rover Radio
(1-B- i) Real-Time Kinematic (RTK)
Base Radio Antenna
RTC
M M
essa
ges
Choke Ring Antenna
• According to RTCM Message Type:– RTK Remote: Centimeter Accuracy– DGPS Remote: Sub-meter Accuracy
• Data Link: a radio link, telephone line, cellular phone or any other medium that can transfer digital data.
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 10
(1-B- ii) OmniSTAR Services Types
Virtual Base Station Virtual Base Station ((VBSVBS) Method) Method
Meter-Level Accuracy
WideWide--Area Carrier Phase Area Carrier Phase Positioning MethodsPositioning MethodsDecimeter-Level Accuracy
The OmniSTAR L-Band Signal:- First provided in Australia in 1995.- Available in the USA since 1997.
Segment:UserSingle Frequency Receiver
Segment:UserDual Frequency Receiver
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 11
OmniSTAR System Component
Atmospheric Correction Message
GPS Satellite
SubscribedLand or Air User
3 Network Control Centers
100 OmniSTARGPS Monitor Sites
6 L- Band Geostationary
Satellite
OmniSTAR Concept of Work
GPS Signal
DGPS Up-Link
6 Uplink StationOmniSTAR GPS
Virt
ual B
ase
Stat
ion
(VB
S)
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OmniSTAR Worldwide Coverage
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 13
Baud RateFrequencySatellite12001535.1525 MHzEA-SAT (Europe)
OmniSTAR EA-SAT Coverage Map
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• Provides Meter-level Accuracy Real-Time positioning using pseudorange code observations.
• Suitable for Moving Applications: the reference station follows the user around.
• Regular Accuracy over The Entire Coverage Area.
• Highly Reliable: It is not dependent on any single reference station.
• No position jumps: VBS gradually changes the contribution of any reference station in the position solution, as the user moves.
• Correction data is available for all GPS satellites in view at the user’s location.
Advantages of OmniSTAR VBS
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OmniSTAROmniSTAR--HP HP ((LandLand))
StarFixStarFix--HP HP ((MarineMarine))
Multiple Reference Multiple Reference StationStation
Precise Orbit and Precise Orbit and Clock MethodClock Method
Wide Area Carrier Phase Wide Area Carrier Phase Positioning MethodsPositioning Methods
StarFixStarFix GSS GSS ((MarineMarine))
SkyFixSkyFix XP XP ((MarineMarine))
Wide-Area Carrier Phase Positioning Methods
Note: The distance to the closest station is more than 500 km
Not location dependent
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• In 1997, Egypt Ports and Lighthouse Authority (PLA) established marine differential GPS radio-beacon service,
• These six stations are in service since 1998(Egyptian notice to mariner number 8/1998 published by PLA on 17/9/1998).
• Cover the two coastlines along the Mediterranean and the Red Sea.
Objective:To provide safe GPS navigation to vessels approaching the Egyptian water and the Suez Canal.
Each DGPS radio-beacon contains:• 2 Single Frequency (L1) GPS reference stations,• 2 Integrity Monitors, • 4 GPS Antennas,• High Frequency Communication Station.
(3) Pseudolites (Beacons) In Egypt
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Difference between GPS satellite and pseudolite: Pseudolite position is described in geographical termsnot in the orbital elements used by satellites.
GPS Satellite
satellite signal direct to user
satellite signal to
Pseudolite
Pseudolite at a known point on the ground
A Pseudolite works as a complete “ground-based satellite”.
Pseudolite makes the following:1. Measures the satellite signals,2. Creates a precisely timed GPS-like signal,3. Then transmits it over a datalink to user.
User
Pseudolite Concept of Work
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 18
Expected Rangeat 75 μV/m (NM)
Power(Watt)
Frequency(kHz)LocationStation
150200307.031º 21´ 33´´ N27º 14´ 48´´ E
MersaMatrouh
150200284.031º 09´ 14´´ N29º 52´ 47´´ EAlexandria
126200290.031º 16´ 22´´ N32º 17´ 32´´ EPort Said
150200298.028º 21´ 07´´ N33º 06´ 37´´ ERas Gharib
126200293.527º 50´ 56´´ N34º 18´ 50´´ ERas Umm Sid
260500314.526º 08´ 16´´ N34º 15´ 39´´ EQuser
Pseudolite Locations in Egypt
They are 6 in number located: • 3 along the Mediterranean: Port Said, Alexandria and Mersa Matrouh.• 3 along the Red Sea: Ras Umm Sid, Ras Gharib and Quser.
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 19
Mersa MatruhMersa MatruhAlexandriaAlexandria Port SaidPort Said
Ras GharibRas GharibRas Umm SidRas Umm Sid
QuseirQuseir
Pseudolite Coverage In Egypt
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• EGNOS stands for European Geostationary Navigation Overlay Service
• It’s the European version of Satellite Based Augmentation Systems (SBAS)
• It is a joint project of the European Tripartite Group (ETG):– European Space Agency (ESA), – The European Commission (EC) and– The European Organization for the safety of the Air
Navigation (EUROCONTROL).
• ESSP has begun the Initial Operations in July 2005, under contract with ESA.
(4) EGNOS
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 21
33 Geo SatellitesGeo SatellitesAOR-E / IND-W/ ARTEMISGNSS SatellitesGNSS Satellites
6 Navigation Land Earth Stations (NLES)
4 Mission Control Centers (MCC)
33 Reference & Integrity Monitoring Stations (RIAM)
EGNOS Wide Area Network (EWAN)
EGNOS Concept of Work
Augmented Navigation
SBASSBASMessageMessage
Integrity & Integrity & Ranging + Ranging + CorrectionsCorrections
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 22
DGPS MAXDGPS MAXZ-MAXZ-MAX
Instruments Used in Test:• Z-Max GPS and GNSS Solution Software from Thales
Navigation:For fixing a point and its post-processing software, GNSS Studio, for post-processing.
• 2 DGPS Max GPS receivers from CSI-Wireless
EGNOS vs. OmniSTAR VBS Test
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Antenna Splitter
EGNOS OmniSTAR
CDA-3 Antenna
EGNOS vs. OmniSTAR VBS Test
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 24
Programs Used:– Autodesk AutoCAD 2004– Microsoft Excel 2003– NMEA Extractor v3.0 with UTM Calculator v1.2 module:
By Ramadan Salem using Microsoft Visual Basic v6.0– Satellite Availability v1.0:
By Ramadan Salem using Microsoft Excel Visual Basic for Applications (VBA).
EGNOS vs. OmniSTAR VBS Test
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 25
Graphs Drawn over Time:
– Position Scatter Plot
– Used Satellite Availability
– Number of Viewed and Used Satellites in Position Calculation
– PDOP, HDOP and VDOP Values
– DGPS Age
– ∆Easting, ∆Northing and ∆Altitude over time
– 2D and 3D Error Distance
– Std. Dev. of Computed Latitude, Longitude and Altitude.
EGNOS vs. OmniSTAR VBS Test
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 26
Data Collected with the Following Conditions:
– Data collected in form of NMEA Sentences using (GGA, GLL, VTG, ZDA, RMC, GSA, GSV, GST and RRE).
– Test Duration: 11 Hours
• Start Time: 13 UTC on 28th of February , 2005• End Time: 00 UTC on 1st of March, 2005
– Mask Angle: 5°
– Record Interval: 1 sec
– Observations with PDOP > 6 are excluded from graphs and statistics.
EGNOS vs. OmniSTAR VBS Test
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 27
Number of Viewed & Used Satellites
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 28
1514131110080704030201292827262524222120191816
Max.Min.VBS129# Sat. Viewed117 #Sat. Used
151413111008070403012928272625242220191816
OmniSTAR VBS:
For EGNOS:
Used Satellites PRN Numbers
Max.Min.EGNOS129# Sat. Viewed94 #Sat. Used
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 29
Om
niST
AR
EGN
OS
Used Satellite Availability over Time
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Max.Min.EGNOS98.03.0PDOP7.70.9HDOP12.71.1VDOP
Max.Min.VBS2.51.3PDOP14.81.4HDOP2.21.0VDOP
DOP Values Over Time
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 32
AverageMax.Min.VBS0.1851.182-1.293∆ E
-0.7240.515-3.101∆ N0.0824.028-3.372∆ Alt.
AverageMax.Min.EGNOS0.0412.02-3.87∆ E
-0.07813.86-3.60∆ N1.23010.03-3.97∆ Alt.
∆E, ∆N and ∆Alt. over Time
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 33
∆E, ∆N and ∆Alt. over Time
∆N
∆E
∆Alt.
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 34
EGNOS
OmniSTAR VBS
Average ∆ E, ∆ N and ∆ Alt. for each 1hr over Test Period
∆E, ∆N and ∆Alt. over Time
METIS Second Master Training & Seminar, Cairo (Egypt), 06-07.11.2007Page 35
Scatter Plot over Test Period
For OmniSTAR VBS:2D Offset Distance (m) = 0.7475 m
For EGNOS:2D Offset Distance (m) = 0.0885 m