Transcript EGNOS TRAN over Loran-C Factory Acceptance Test

The Challenge of Finding Your
Position in a World Hostile
to Radio Navigation
Prof.dr. Durk van Willigen
Reelektronika, Netherlands
ILA 2003
Boulder, Colorado, USA, 3-7 November 2003
Durk van Willigen
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Overwhelming GPS Success
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GPS revolutionised navigation
GPS is embraced by its users
GPS never fails 
Emerging worries on GPS 
Concern  PCCIP  Volpe Report
US leads rethinking on vulnerability GPS
From sole-means  dissimilar systems 
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Vulnerability a today’s Issue?
• Yes, because society never relied so
strongly on a single source of navigation
and time before the GPS era
• Yes, because never before the bad guys
were able to disable our core navigation
and time sources so easily and
untraceably, and over such large areas
• Yes, because many do not recognize this
flaw and do not take timely precautions
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User’s Attitude
• We have GPS, it performs excellent, it is
extremely cost-effective, so why worry?
• Question: Imagine living without fire fighters,
vaccination, life-boats, police, dikes, …
• We have them all, we generously pay for it, but
we are convinced that we will never need them
• Fortunately, we don’t need such precautions for
GPS or GLONASS or Galileo because these
systems are perfect !!
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Why Galileo next to GPS?
• Because Europe is an industrial high-tech
world player
• Europe aims to be successful in GNSS
technology just as it is with Airbus, ESA,
Concorde, TGV, GSM, Bach, Rembrandt, ….
• But like the US, Europe prefers to be autonomous in respect of navigation and timing
• Europe is keen to make profit with its own
Galileo business
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US-European Navigation Co-operation?
• Users will like Galileo as it doubles the
number of navigation satellites improving
availability in city areas
• Professional navigators think Galileo may
reduce the single-point-failure effects in
the technical and control segments
• US military highly dislikes Galileo’s PRS
as it makes GPS’ M-code less effective
• PRS = Public Restricted Services
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PRS versus M-code
• The US officially and repeatedly stated that it will
deny all non-US satellite navigation services if
US national security requires so
• Europe would like to prevent that
• Europe might also deny GPS to many other
countries if needed
• Question from a simple not involved observer:
– Does the US rule GNSS like the UK ruled the waves?
– Are the US and Europe each others hostages?
• In all public statements these issues are not
mentioned of course (ION-GPS 2003)
• What is the discussion all about?
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L1 spectrum (USA at ease)
C/A / -157 dBW
M-code / -158 dBW
(Earth Coverage Mode)
P(Y) / -160 dBW
GPS IIF
US-Europe
Conflict
1560
1565
1570
OS / -152 dBW
1575
1580
1585
1590
PRS / -152 dBW ?
Galileo
1555
Durk van Willigen
PRS / -152 dBW ?
1560
1565
1570
1575
1580
1585
1590
1595
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Denial Dilemma
• Imagine that the US would ever like to
deny GPS to non-US countries by
jamming civil parts of GNSS bands
• Then GPS CA and Galileo OS will stop 
– OS = Open Service
• So, the US continues with M-code and
Europe with its PRS 
• But if US would like to deny PRS also then
it will harm its own M-code as well, or the
other way around with identical effect 
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L1 spectrum (USA in action)
Spot Beam Mode
-138 dBW (+20 dB)
All non M-code signals
on L1, L2, and L5 can
be denied
1555
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1565
1570
1575
1580
1585
1590
1595
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Solution?
• Increase GPS M-code signal power levels
by e.g. 20 dB in selected areas so that
jamming PRS will not kill M-code signals
as a collateral damage 
• But what will happen if Europe would take
identical initiatives? 
• Challenging issue for American and
European politicians 
• Or, is it a technical challenge only? 
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Who Might Endanger GNSS?
• Hackers
• Feels good to get large user groups on a string
• Compare with virus creators
• Road users
• Attempt to cheat the system to get a free ride
• Thieves
• Disable car-theft protection systems
• Disable GNSS-based tracking and tracing of valuable cargo
• Terrorists
• Use your own imagination and, please, don’t tell anybody the
results
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Very Annoying L1 Dinky Toy
• Low GNSS power
levels makes jamming
relatively easy
– Just 100 Watts to
illuminate 38% of
earth’s surface
• Much progress
observed today in
jamming rejection
technology
– Outside military world
not yet available
– Complex
– Fail safe?
Durk van Willigen
•
•
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•
•
1 mW L1 jammer
100 meters range
30 mm on a side
4 hours on single battery
Not for sale !!
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A Powerful Solution
• Avoid Single-Point-Failure Structure
through integration of highly dissimilar
sub-systems
• Which systems are dissimilar to GPS?
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Integrated Navigation Concept
Inputs
Position
Determination
Navigation &
Guidance
Outputs
Navigation
Information &
Guidance/
Display
Signal
Generation
Autopilot
Sensor 1
Absolute Raw
Positioning Data
Sensor k
Sensor 1
Selection, Acquisition, Track aiding
Incremental Raw
Positioning Data
Sensor l
Sensor 1
Relative Raw
Positioning Data
Sensor m
Datalink 1
Integrated
Position,
Velocity,
Attitude,
Heading &
Integrity
Determination
Augmentation
Data Broadcast
Pilot Output
Nav Displays
Datalink n
Traffic Control and
Route Guidance
Traffic Control
Channel Input
Traffic Control
Channel Output
Sensor System &
Terrain/Roadmap
Database
Navigation Plan &
Navigation
Database
Pilot Input
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Galileo backing up GPS?
• Yes, because
–
–
–
–
Galileo has higher power level
Galileo uses some un-modulated carriers
More satellites yield better availability
If one control link fails the other one may survive
• No, because
– Low dissimilarity in frequency and power levels
– Denial requirement of the other party
• Conclusion: Other very dissimilar systems
needed
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Strengths/Weaknesses Navigation
Galileo/GPS/GLONASS
Loran-C/Chayka
(Un-)intentional long-range
interference robustness
Low
Very high
Unintentional short-range
interference robustness
High
Low*
Accuracy
High / Very high
Medium / High**
Availability in urban areas
Medium
High
Reliability
High
High
Initial provider costs
High
Medium
Recurring provider costs
Medium
Low
* Interference from e.g. car generators, computer monitors, etc
** Medium accuracy with accurate ASF tables, high accuracy with DLoran-C or SLA technology
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GNSS versus Loran
GNSS
Loran-C
Phenomenon
Risk
Effect
Solution
Risk
Effect
Solution
Long-range
interference
robustness
Low
High
BSA + DSP
Low
Low
DSP
Short-range
interference
robustness
Low
High
None
(non-linearity)
Medium
High
BSA + DSP
Spoofing
Low
Very high
RA(S)IM
Very low
Low
RA(S)IM
Shadowing
Medium
Medium
Many SVs
Low
Low
n.a.
Multipath
Medium
Medium
BSA +
MEDLL
Low
Medium
BSA + DSP
BSA = Beam Steering Antenna
DSP = Digital Signal Processing
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Questions
• If Loran is that good why are there no GPS-like
receivers available?
• Why are there no integrated GPS-Loran
receivers?
• How to integrate GPS and Loran-C?
• Integrate or mutually calibrate?
• What is the real error budget chain under
adverse signal conditions?
• Why are inertial sensors not integrated with
Loran to increase dynamic response?
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Frankfurt Down-Town
New Loran-C receiver not
yet available at time of test
Tall buildings and narrow streets
in Financial Center of Europe
GPS suffers from shadowing and
multipath
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GPS only in Frankfurt
111 m/div
71 m/div
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GPS-INS Integrated
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Unaided Versus Aided GPS
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TOA Tracking Accuracy @ Boston: 5m 95%
10
8
Integrate and dump
every 5 seconds
6
Latitude Error (m)
Measurements in
Boston harbor
Calibra
Integra
NovAt
4
2
0
-2
FAA LORAPP program
(LORAPP =
LORan Accuracy
Performance Panel)
-4
-6
-10
-8
-6
-4
-2
0
2
4
Longitude Error (m)
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Local Interference Cancellation-1
8000
Time Domain
6000
4000
2000
0
-2000
-4000
-6000
3340
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3380
3400
3420
3440
3460
3480
3500
3520
3540
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Local Interference Cancellation-2
120
Frequency Domain
115
[dB]
110
105
100
95
90
85
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95
100
Frequency [kHz]
105
110
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TOA Tracking Stability @ Boston
TOA, 30 sec integrated
0
5930X
Y-axis = 30 m/div
Time jumps due
to transmitter
time control
steps of 20 ns,
equivalent to 6 m
-0.1
9960X
8970X
us
-0.2
9960M
-0.3
5930M
-0.4
9960W
-0.5
9960Y
0
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100
150
200
250
time (minutes)
300
350
400
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Strengths/Weaknesses Augmentation
WAAS/EGNOS/MSAS
EGNOS via Eurofix
Long-range interference
robustness
High*
Very low
Short-range interference
robustness
Low
Medium
Availability in urban areas
Medium
High
Availability in Polar Region
None
High**
Reliability
High
High
Initial provider costs
High
Very low
Recurring provider costs
Medium
Very low
* Not relevant as under jamming conditions GNSS will fail too
** To be confirmed by real-life tests in the Artic Region. Covering Polar Region requires US and Russian stations to
broadcast DBAS data too
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EGNOS/Eurofix Station at 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
Thales
EGNOS
GPS
Antenna
Eurofix
Integrity
Monitor
GPS
Antenna
Durk van Willigen
Eurofix
Eurofix
Datalink Reference
Monitor
Station
Loran-C
GPS
Antenna Antenna
← Integrity Monitor PC
← Reference Station PC
← UPS
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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
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
7001X+9007W
250 kW
7001Y
250 kW
4970M+5960Z
1,200 kW
• ‘Polar Routes
Feasibility Study’,
Nav Canada and
FAAR, October 2000
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Integrated GPS/Loran/Eurofix Receiver
Signal Processor
77 x 51 mm
Durk van Willigen
Front End & ADC
77 x 47 mm
Credit Card
85 x 54 mm
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H-Field Antenna Testing
• Antenna testing requires many
skills and lots of enthusiasm
• High performance Loran
receivers need many aspects
to be verified
• Most Loran-C challenges are
known today, and are taken
care of
• Loran development is a multidisciplinary task
Antenna
under test
H-field
generating
loop
PC-controlled
turn table
• Much progress observed in US,
Asia and Europe
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Conclusions
• Loran-C/Chayka is the only wide area multimodal navigation life boat if GNSS fails
• Skywave and man-made interference largest
challenge to Loran-C land applications
• Loran-C receivers without GPS chip set may
have a too low market appeal
• With land applications low-cost rate gyros and
odometers may be of good help to smooth
tracking and to coast if both Loran and GPS fail
• Large advances in Loran-C technology must
now be marketed at high speed to create
critical mass to keep Loran-C/Chayka alive!!
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