The Challenge of Finding Your Position in a World Hostile to Radio Navigation
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Transcript of The Challenge of Finding Your Position in a World Hostile to Radio Navigation
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Durk van Willigen
1reelektronika
The Challenge of Finding Your Position in a World Hostile
to Radio Navigation
Prof.dr. Durk van Willigen
Reelektronika, Netherlands
ILA 2003Boulder, Colorado, USA, 3-7 November 2003
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Durk van Willigen
2reelektronika
Overwhelming GPS Success
• 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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Durk van Willigen
3reelektronika
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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Durk van Willigen
4reelektronika
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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Durk van Willigen
5reelektronika
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 auto-nomous in respect of navigation and timing
• Europe is keen to make profit with its own Galileo business
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Durk van Willigen
6reelektronika
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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Durk van Willigen
7reelektronika
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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Durk van Willigen
8reelektronika
L1 spectrum (USA at ease)
P(Y) / -160 dBW M-code / -158 dBW(Earth Coverage Mode)
C/A / -157 dBW
1565 15801575 1585 159015701560
GPS IIF
1565 15801575 1585 159015701555 15951560
Galileo
OS / -152 dBW PRS / -152 dBW ?
PRS / -152 dBW ?
US-Europe Conflict
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Durk van Willigen
9reelektronika
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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Durk van Willigen
10reelektronika
L1 spectrum (USA in action)
Spot Beam Mode-138 dBW (+20
dB)
1565 15801575 1585 159015701555 15951560
All non M-code signals on L1, L2,
and L5 can be denied
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Durk van Willigen
11reelektronika
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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Durk van Willigen
12reelektronika
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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Durk van Willigen
13reelektronika
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?
• 1 mW L1 jammer• 100 meters range• 30 mm on a side• 4 hours on single battery• Not for sale !!
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Durk van Willigen
14reelektronika
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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Durk van Willigen
15reelektronika
Integrated Navigation Concept
Sensor 1
Sensor 1
Sensor l
Sensor k
Sensor 1
D ata link 1
Traffic C ontro l C hannel Input
Traffic C ontro l C hannel O utput
D ata link n
Increm enta l R awPosition ing D ata
Absolute R awPosition ing D ata
R elative R awPosition ing D ata
Augm entation D ata B roadcast
Traffic C ontro l and R oute G uidance
Sensor m
IntegratedPosition,Velocity,A ttitude,
H eading &Integrity
D eterm ination
Sensor System &Terra in /R oadm ap
D atabase
N avigation P lan &N avigation D atabase
N avigationInform ation &
G uidance/ D isp layS ignal
G eneration
Selection, Acquisition, Track a id ing
Inputs OutputsPositionDetermination
Navigation &Guidance
Pilot Input
P ilo t O utputN av D isp lays
Autopilo t
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Durk van Willigen
16reelektronika
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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Durk van Willigen
17reelektronika
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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Durk van Willigen
18reelektronika
GNSS versus Loran
GNSS Loran-CPhenomenon Risk Effect Solution Risk Effect Solution
Long-range interference robustness
Low High BSA + DSP Low Low DSP
Short-range interference robustness
Low HighNone
(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 MediumBSA + MEDLL
Low Medium BSA + DSP
BSA = Beam Steering Antenna
DSP = Digital Signal Processing
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Durk van Willigen
19reelektronika
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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Durk van Willigen
20reelektronika
Frankfurt Down-Town
Tall buildings and narrow streets
in Financial Center of Europe
GPS suffers from shadowing and multipath
New Loran-C receiver not yet available at time of
test
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Durk van Willigen
21reelektronika
GPS only in Frankfurt
111 m/div
71 m/div
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Durk van Willigen
22reelektronika
GPS-INS Integrated
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Durk van Willigen
23reelektronika
Unaided Versus Aided GPS
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Durk van Willigen
24reelektronika
TOA Tracking Accuracy @ Boston: 5m 95%
Calibrated LoranIntegrated NavNovAtel POSA
Longitude Error (m)420-2-4-6-8-10
Latit
ude
Err
or (
m)
10
8
6
4
2
0
-2
-4
-6
Measurements in Boston harbor
Integrate and dump every 5 seconds
FAA LORAPP program
(LORAPP =LORan Accuracy Performance Panel)
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Durk van Willigen
25reelektronika
Local Interference Cancellation-1
3340 3360 3380 3400 3420 3440 3460 3480 3500 3520 3540
-6000
-4000
-2000
0
2000
4000
6000
8000
3340 3360 3380 3400 3420 3440 3460 3480 3500 3520 3540
-6000
-4000
-2000
0
2000
4000
6000
8000
Time Domain
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Durk van Willigen
26reelektronika
Local Interference Cancellation-2
85 90 95 100 105 110
90
95
100
105
110
115
120
Frequency [kHz]
[dB
]
85 90 95 100 105 110
90
95
100
105
110
115
120
Frequency [kHz]
[dB
]
Frequency Domain
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Durk van Willigen
27reelektronika
0 50 100 150 200 250 300 350 400
-0.5
-0.4
-0.3
-0.2
-0.1
0
5930X
9960X
8970X
9960M
5930M
9960W
9960Y
time (minutes)
us
TOA, 30 sec integrated
TOA Tracking Stability @ Boston
Y-axis = 30 m/div
Time jumps due to transmitter time control steps of 20 ns, equivalent to 6 m
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Durk van Willigen
28reelektronika
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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Durk van Willigen
29reelektronika
EGNOS/Eurofix Station at Sylt
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
← UPS
Equipment RackAntenna mounts
ThalesEGNOS
GPSAntenna
EurofixIntegrityMonitor
GPSAntenna
EurofixReference
StationGPS
Antenna
EurofixDatalinkMonitorLoran-CAntenna
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Durk van Willigen
30reelektronika
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
4970M+5960Z 1,200 kW
4970X+5960Y 250 kW
5960X 1,200 kW
7001Y 250 kW7270X+5930Z
800 kW
7960M 560 kW
9990Y+7960Z 1,000 kW
7001X+9007W 250 kW
9990Y+7960Z 1,000 kW
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Durk van Willigen
31reelektronika
Integrated GPS/Loran/Eurofix Receiver
Credit Card 85 x
54 mmFront End &
ADC77 x 47 mm
Signal Processor77 x 51 mm
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Durk van Willigen
32reelektronika
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 multi-
disciplinary task
• Much progress observed in US,
Asia and Europe
Antenna under test
H-field generating
loop
PC-controlled turn table
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Durk van Willigen
33reelektronika
Conclusions
• Loran-C/Chayka is the only wide area multi-modal 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!!