Transcript EGNOS TRAN over Loran-C Factory Acceptance Test

EGNOS TRAN: Broadcasting
EGNOS messages over the
Eurofix Datalink
Gerard Offermans,
Arthur Helwig & Durk van Willigen
Reelektronika, the Netherlands
ILA 32 – 4-7 November 2003
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Gerard Offermans - reelektronika
What is EGNOS?
• EGNOS = European WAAS
• Differential Corrections and Integrity for GPS
• Ground network of RIMS measure satellite
range errors
• Range errors are spit into ionospheric
component and satellite specific errors
• Broadcast of Wide-Area data via
Geostationary Satellites
• All based on RTCA DO-229B documentation
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Why EGNOS TRAN?
EGNOS GEO visibility in München
EGNOS
NOT Visible
EGNOS
Visible
From: The GLORIA Project by M. Maurer, ILA-29, Washington, DC.
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EGNOS TRAN solution
• Eurofix datachannel capacity appr. 30 bps
• EGNOS bandwidth 250 bps
EGNOS TRAN solution
• EGNOS TRAN does not back-up GEO
datalink
• EGNOS TRAN backs-up EGNOS
functionality
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EGNOS TRAN Local Area solution
• EGNOS receiver outputs RTCM SC104
LAAS correction data for all satellites in
view of Loran Transmitter
• Eurofix Station converts this message to a
standard Eurofix message
• User gets Local Area correction
– Input into standard GPS receivers
– Suffers from Spatial Decorrelation
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EGNOS-Eurofix Local Area
EGNOS
satellite
Eurofix
data
RTCM
Thales EGNOS
RX
EGNOS
PC
Loran-C
pulses
Loran-C
TX
250 kW
Loran-C TX
RTCM to Eurofix data
conversion & Eurofix
transmission control
H-field
Loran-C
Antenna
RTCM
DGPS RX
Eurofix RX
GPS
Antenna
Including Eurofix to
RTCM data conversion
DGPS user
position
EGNOS Rx calculates RTCM corrections based on reference position and EGNOS data
EGNOS/Eurofix PC unpacks RTCM messages and reformats to standard Eurofix messages
User receives standard Eurofix messages and applies as LAAS correction
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EGNOS TRAN Wide Area solution
• EGNOS receiver provides “raw” EGNOS data
• Eurofix Station extracts information and reduces
dataset
• Eurofix Station reformats information into ETRAN Eurofix message
• User calculates ionospheric delay and satellite
clock errors for all satellites based on estimated
User position
– Pure Wide Area solution
– No spatial decorrelation
– Requires position feedback to the Eurofix receiver
(GPS or Loran-C)
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EGNOS-Eurofix Wide Area
EGNOS
satellite
Eurofix
data
EGNOS
format
Thales EGNOS
RX
EGNOS
PC
EGNOS to Eurofix data
conversion & Eurofix
transmission control
Loran-C
pulses
Loran-C TX
250 kW
Loran-C TX
NMEA
(position)
H-field
Loran-C
Antenna
RTCM
DGPS RX
GPS
Antenna
Eurofix RX
Including EGNOS
Eurofix to RTCM data
conversion
DGPS user
position
Thales Rx passes DO-229 EGNOS data on to EGNOS PC
EGNOS PC unpacks EGNOS data and reformats into EGNOS Eurofix messages
User receiver receives Eurofix messages and stores EGNOS data
User receiver calculates optimal correction data based on user position (true wide area)
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ETRAN Message Types
E-TRAN
Type
EGNOS
Source
Content
0
Do not use !
1
Fast corrections, 2 satellites/message
2
Fast & slow correction, 1 satellite/message
3
Slow correction, 1 satellite/message
25
4
Ionospheric grid
18
5
Ionospheric Grid delay model parameters,
3 IGPs/message
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ILA 32 – 4-7 November 2003
0
9
2-5
2-5 + 25
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Wide Area EGNOS TRAN message types
ETRAN type 0 – Do not use data
Field
Bits
# bits
Units
Range
Eurofix Type (8)
1-4
4
16
ETRAN Type (0)
5-7
3
8
Body (all zeroes)
8-56
49
CRC
57-70
14
Source: EGNOS message 0! (WAAS compatibility mode)
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Wide Area EGNOS TRAN message types
ETRAN type 1 – Fast correction (2 satellites/message)
Field
Bits
# bits
Units
Eurofix Type (8)
1-4
4
16
ETRAN Type (1)
5-7
3
8
Satellite ID
8-15
8
256
Fast correction
16-27
12
UDREI
28-31
4
0-16
Satellite ID
32-39
8
256
Fast correction
40-51
12
UDREI
52-55
4
Spare
56
1
CRC
57-70
14
0.125 m
0.125 m
Range
-256 – 255.875 m
-256 – 255.875 m
0-16
Source: EGNOS message 2,3,4,5 (satellite fast corrections)
EGNOS message 0! (WAAS compatibility mode)
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Wide Area EGNOS TRAN message types
ETRAN type 2 – Fast & Slow correction (1 sattellite/message)
Field
Bits
# bits
Units
Eurofix Type (8)
1-4
4
16
ETRAN Type (2)
5-7
3
8
Satellite ID
8-15
8
256
Fast correction
16-27
12
UDREI
28-31
4
0-16
IOD
32-39
8
256
δaf0
40-50
11
Spare
51-56
6
CRC
57-70
14
0.125 m
Range
-256 – 255.875 m
2-31 s
2-21 s
Source: EGNOS message 2,3,4,5,0 (satellite fast corrections)
EGNOS message 25 (satellite slow corrections)
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Wide Area EGNOS TRAN message types
ETRAN type 3 – Slow correction (1 satellite/message)
Field
Bits
# bits
Units
Range
Eurofix Type (8)
1-4
4
16
ETRAN Type (3)
5-7
3
8
Satellite ID
8-15
8
256
IOD
16-23
8
256
δaf0
24-32
9
2-31 s
2-23 s
δx
33-40
8
0.250 m
-32 – 32
δy
41-48
8
0.250 m
-32 – 32
δz
49-56
8
0.250 m
-32 – 32
CRC
57-70
14
Source: EGNOS message 25 (satellite slow corrections)
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Wide Area EGNOS TRAN message types
ETRAN type 4 – Ionospheric Grid
Field
Bits
# bits
Units
Range
Eurofix Type (8)
1-4
4
16
ETRAN Type (4)
5-7
3
8
Grid Sub ID
8-9
2
4
Total Subs
10-11
2
4
IODI
12-13
2
0-3
IGP mask bits
14-53
40
Spare
54-56
3
CRC
57-70
14
Source: EGNOS message 18 (ionospheric grid mask)
Eurofix station coverage area & Gridpoints ‘in view’
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Wide Area EGNOS TRAN message types
ETRAN type 5 – Ionospheric Grid delay model parameters (3 IGPs/message)
Field
Bits
# bits
Units
Eurofix Type (8)
1-4
4
16
ETRAN Type (5)
5-7
3
8
IODI
8-9
2
0-3
First Grid point
10-17
8
160
IGP vertical delay estimate
18-26
9
Grid IVEI
27-30
4
IGP vertical delay estimate
31-39
9
Grid IVEI
40-43
4
IGP vertical delay estimate
44-52
9
Grid IVEI
53-56
4
CRC
57-70
14
0.125 m
Range
0-63.875 m
0-15
0.125 m
0-63.875 m
0-15
0.125 m
0-63.875 m
0-15
Source: EGNOS message 26
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Wide Area EGNOS message distribution
Satellite and Ionospheric corrections are interleaved:
2 Satellite Corrections to 1 Ionospheric Correction
Fast and slow corrections are
interleaved (2 to 1)
2 type-1 Fast corrections
(2 SVs)
1 type-2 Fast & slow correction
or type-3 Slow correction
Grid and IGP data messages are
interleaved (1 to 7)
1 type-4 Ionospheric grid
7 type-5 IGP data (3 IGPs)
In total 113 IGP points for Sylt area, so a whole transmission sequence is:
3 type-4 messages (grid) + 38 type-5 messages (IGP data) interleaved 2 to 1
Approximately 123 (=3 times 41) messages before all (IGP) data is acquired
Sylt update rate is one message every 2 seconds (single rate)
EGNOS TRAN Cold start acquisition time 246 seconds (4 minutes)
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Installation at Loran-C station Sylt
250-kW Solid State transmitter @ 100 kHz
200-m Antenna mast
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Installation at Loran-C station Sylt
Antenna mounts
Equipment Rack
EGNOS TRAN equipment
← Thales EGNOS Rx
← Modem & power supply
← EGNOS TRAN PC
Existing Eurofix installation
← Eurofix Rx & power supply
← 2x GPS Rx & Modem
← CPU switch
← Integrity Monitor PC
← Reference Station PC
Thales
EGNOS
GPS
Antenna
Eurofix
Integrity
Monitor
GPS
Antenna
ILA 32 – 4-7 November 2003
Eurofix
Eurofix
Datalink Reference
Monitor
Station
Loran-C
GPS
Antenna Antenna
← UPS
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LORADD EGNOS TRAN Receiver
Get your EGNOS TRAN receiver upgrade today!!!
**
• ‘All-in-view’ Loran-C/Eurofix receiver, tracks all stations
• Improved Loran tracking and Eurofix datalink performance through
advanced DSP algorithms
• Modified to perform User Differential Correction calculations based on
received EGNOS TRAN messages
• Used in trials with EGNOS TRAN on 6731Z and Eurofix on 7499M (Sylt)
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Measurements
• Performed by Teleconsult Austria
Country
– The Netherlands
– Germany
– France
– Sweden
ILA 32 – 4-7 November 2003
Mode
E-TRAN LAAS
E-TRAN LAAS
E-TRAN LAAS
E-TRAN RAAS
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Measurement results - Göteburg
ILA 32 – 4-7 November 2003
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Measurement results - Göteburg
ETRAN 100% availability
EGNOS GEO: 100% availability
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Measurement results
• EGNOS TRAN Datalink performed well,
even in areas where GEO is unavailable
• Generally, where GEO and EGNOS TRAN
via Eurofix are available, the DGPS
performance is similar
• E-TRAN Local Area mode is less accurate
than E-TRAN Wide Area mode
(spatial decorrelation)
• Proven EGNOS functionality back-up
using “low bit-rate” data channel
ILA 32 – 4-7 November 2003
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Potential
European
Eurofix
coverage
…which is
about the
footprint of
EGNOS
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Polar Routes
• Restricted Russian
polar routes: Polar 1
to 4
• Preferred random
routing in Canada
• 2005: 9000+
commercial polar
flights estimated
• Savings:
– Flying time: 2+ hrs
– Costs: US$ 16
k/flight
– Time slots Atlantic
• ‘Polar Routes
Feasibility Study’,
Nav Canada and
FAAR, October 2000
ILA 32 – 4-7 November 2003
7960M
560 kW
9990Y+7960Z
1,000 kW
9990Y+7960Z
1,000 kW
5960X
1,200 kW
4970X+5960Y
250 kW
7270X+5930Z
800 kW
25
7001X+9007W
250 kW
7001Y
250 kW
4970M+5960Z
1,200 kW
Gerard Offermans - reelektronika
Conclusions
• ETRAN exceeds SBAS availability in cities, forests
and mountainous environment
• Loran-C navigation function very dissimilar backup
for GPS outages
• Loran-C TX modification low-cost, especially if
station has access to WAAS or EGNOS data
networks
• Can be implemented on Eurofix in Europe as well
as on Loran-Comm in the US
• E-TRAN Data update can easily be improved by
using dual-rate and multiple stations
ILA 32 – 4-7 November 2003
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More information
• http://galileo.cs.telespazio.it/egnostran/
• http://galileo.cs.telespazio.it/egnostran/
home/files/etran4gis.pdf
• [email protected]
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