Copyright B. Parkinson July 2007 The Future of Satellite Navigation (PNT) Professor Brad Parkinson Stanford University Much Credit and many thanks to Inside GNSS & GPS World for photos "You've got to be very careful if you don't know where you are going, because you might not get there." – -- Yogi Berra
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Copyright B. Parkinson July 2007
The Future ofSatellite Navigation
(PNT)Professor Brad Parkinson
Stanford UniversityMuch Credit and many thanks toInside GNSS &
GPS World for photos"You've got to be very careful if you don't know where you are going,
because you might not get there." –
-- Yogi Berra
2Copyright B. Parkinson July 2007
Purpose of this TalkDiscuss the Future of PNT:
• Navigation Satellite Systems• Augmentation Systems• Applicable Technology and
• User Applications
plus
• Issues for sustaining Civil Capability
For Satellite-based PNT
3Copyright B. Parkinson July 2007
CONTEXT: The “Big Five”Civil Goals for GPS (GNSS) (As recommended by the IRT)
GPS IIF Space Vehicle Weight- 1,672 kg (3,758 lbs)
Launch Vehicle• EELV (Delta IV, Atlas V)
Improvements/Upgrades from prior satellitesinclude:• Design life of 12 years• Twice the payload power of IIR satellites (2.440 kW)• Signals: L1 C/A, L1 P(Y), L1 M, L2 C/A, L2 P(Y), L2 M,
L3, L5
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Summary GPS – The Future IIRM(last) to add L5 IIF to be Launched – end of 2008 GPS III in Source Selection (RFP last July)
• Backwards Compatible• All IIF (IIRM+) signals• L1C – International Civil Signal• Higher Power with Flex• Improved Position and Timing Accuracy
Breakthrough: Instantaneous RTK through combination of GPS & Galileo
Agreement on Interoperability with GPS• But does this mean “Interchangeability?
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Quazi –Zenith Satellite System (QZSS)
Japanese Regional, Multi-use system
Supplement to GPS System
Includes WAAS like function
Adds communications and reporting
1st satellite 2010 (following several years later)
Orbits similar to USAF 621B of 1967• Regional coverage - “elliptical-synchronous”
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QZSS Orbit Constellation
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QZSS Ground Track and Coverage
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Original Planned Services of QZSS
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QZSS Technical Capabilities
??
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Original QZSS Applications
Japanese Quasi-Zenith Satellite System (QZSS)
Services of QZSS
Applications of QZSS
Source: Advanced Space Business Corpration.
Last updated: Thu, June 17, 2004 14:26
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Compass (Beidou) by ChinaThe Satellites
CommentOps?Loc.Constell.LocationLaunchSatellite
?MEOCZ-3AXichang14 Aug07BeiDou-1E
Recovered from asolar panelfailure
?GEO58.75°E
CZ-3AXichang3 Feb 07BeiDou-1D
YesGEO110.5°E
CZ-3AXichang25 May03BeiDou-1C
YesGEO80°ECZ-3AXichang21 Dec
00BeiDou-1B
YesGEO140°ECZ-3AXichang31 Oct
00BeiDou-1A
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Compass (Beidou) Accuracy:
• positioning 10 meters, velocity - 0.2 meter per second timingaccuracy - 50 nanoseconds.
System : To include at least 35 satellites• five geostationary Earth orbit (GEO)• 30 medium Earth orbit (MEO) satellites
4/14/2007 9:15:57 AMChina have successfully launched their second Compassnavigation satellite, which lifted off 4:11 am local time onSaturday from the Xichang Satellite Launch Center. TheLong March 3-A launch vehicle placed the Beidou-2Bsatellite in a 21,500 km orbit.
• Satellites transmit at 2491.75+/-4.08MHz• Ground receiver transmits back at 1615.68MHz.• The BeiDou reference - Beijing 1954 Coord. Sys.• Time reference Chinese UTC
East of 70 52.2W, 95% = 11.7 mWest of 70 52.2W, 95% = 18.3 m
Example Marine Data: Boston HarborExample Marine Data: Boston Harbor
eLORAN as Augmentation to GPS Demonstrated capability
for NPA Robust back-up signal Potentially “seamless”
backup for GPS users Relative cost is small Studied by IAT of IDA A potential deterrent to
deliberate interference
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Some Technologies of the Future
More use of “Real-time” Kinematic
New Signal Structures (e.g.L1C)
Beam Steering Antennas
Chip Scale Atomic Clocks
Deeper “system-level” integration
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Real-Time Kinematic: Today
L1 Code and Carrier L2 Carrier Data Link
10 km10 km
2 cm accuracy2 cm accuracy
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Galileo – How willRTK improve ?
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GPS Satellite Visibility for RTK
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GPS+Galileo Satellite Visibility for RTK
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RTK Accuracy-some improvement with Galileo
1 Cm
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Instantaneous RTK Reliability
1000 times betterfailure rate at 25 km
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CSAC (Chip Scale Atomic Clock)
In April 2005, Symmetricom demonstrateda 10 cc, 200 mWMiniature Atomic Clock (MAC) -surpassed DARPA's stability objectives
CSAC technology evolving to a smaller sizeand lower power, next demonstrate a laboratory prototype of a 1 cc,30 mW atomic clock.
At 100 seconds of integration time, the MAC stability is 4 parts in 10^11,equivalent to gaining or losing 1 second every 10,000 years
GNSS Payoffs• Quicker acquisition/re-acquisition
• Longer integration Times
• Can substitute for a satellite
~10 Seconds to drift ½a GPS wavelength
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Beamforming Antenna Technology All Digital
(improved affordablity)
Adapt to Satellite location(MEMS-IMU helps)
Reduced interference andMultipath
Space-Frequency AdaptiveProcessing can be included
Rejection ratios of 20dB ormore possible
Caution - small phase shifts:• Carrier up to 100o
• Code up to 1 Meter Courtesy Inside GNSS and Prof Lachapelle
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L1C will hopefully be MBOC(6,1,1/11)Common signal provides
hope for “interchangeability”
Codeless channel for long integration times
BOC vs MBOC• MBOC provides more power in higher frequencies
- Crisper definition of “edges’- Better multipath rejection
Courtesy Inside GNSS and Prof. Hein
This signal is symbolic of International Cooperation
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So what are the major new (orexpanded) applications going to be?"Predicting the future is easy. It's trying to figure out
what's going on now that's hard.“ - Fritz R. S. Dressler
Expanded Crustal Tracking Precicion Tracking and Reporting Robotic or Assisted Control Cell/GPS explosion – where will this go?
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Slow “earthquakes” areobserved in Cascadiaand Japan along thesubduction zones.
In Canada, these events take about 15 days,propagate northward, and occur every 16-18months.
GPS is Vastly Increasing our Understanding of Crustal Motion andEarthquakes
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The Northridge Earthquake Affected the Sierra Madre Fault 30 Km Away
Res
idua
l Lon
gitu
de (c
m)
• The earthquake probably triggered shallow slip on the Sierra Madre Fault.• This was the first time that long range fault interactions were observed.• Recent GPS Results Show Concentrated Deformation Near Downtown Los
Angeles
Sierra Madre Fault
1meter
JPL’s GPS station changed its motion as a result ofthe earthquake
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Tracking Applications Have Proliferated
GPS is
the key
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Another Precision Tracking Example(Optimizing Skiing Trajectories- courtesy “Inside GNSS” magazine
• GPS/IMU smoothed trajectory
• Also to be Applied to Autos
• Authors•Adrian Wagli & Jan Skaloud
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Robotic Use Of GPS
Typical Accuracy-Four Inches
Blind Landing Tests – 110 straight successes with one go around
Stanford Robot Tractor
Note fourantennas toprovide 0.1o
Attitude
Tracking Test @ 5 m/s – worst error ~3 inches!
Autonomous Model Helicopter
GPS Position, Velocity and Attitude
“Sandstorm” Vehicle negotiating difficultTerrain
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GPS in GSM Receivers 2011(69% of the Market, by units)
Current ASP ~ $2At $4 per unit-
100% of high endGSM Market
At $2 per unit –100% of the totalGSM market
? IMPLICATIONS ?
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Some Other Interesting Applications
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Towards Auto-guided Automobiles
Vector KinematicRecievers
MEMS/IMURadarsCooperative Tracking
of other vehicles
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And Perhaps the most Humanitarian:
Removing Unexploded Ordinance
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A Caution:Three Critical Issues
for GPtS
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GPS Applications have Proliferated
Military Civil
• Transportation- Aviation- Automobile- Maritime- Rail Control
• Public Services• Timing &
Frequency• Surveying• Surveillance• Other
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We are Victims of our success:
GPS Enormous Capability
Worldwide DependencyWhat must we do to insure that the
GPS Issue #3 –GPS and Galileo-True, Total Interoperability
Payoff – Availability, Accuracy and Robustness
Real Measure: Interchangeability “Mix and Match” with same ranging accuracy• L1C defined, implemented, and operable• Seamless WAAS/EGNOS/+ ?• True clock Synchronization and common grid
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As providers of GtPS
we must insure the Service
is Always Available - To meet:
the Safety, Economic, and Convenience
Needs
of the World
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Conclusions: The FutureNew GPtS signals means better fulfillment of
the “Big Five”Resulting Applications will increasingly be
dependent on robustness, accuracy, andavailability
Caution: the next six years may have degradedperformance if new systems continue to slip