The Future of Satellite Navigationv11 - Stanford...

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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


CONTEXT: The “Big Five”Civil Goals for GPS (GNSS) (As recommended by the IRT)

1. Assured Availability of GPS signals-Includingimpaired situations (mountains, urban areas, foliage, etc.)

2. Resistance to Interference (RFI)

3. Accuracy

4. Bounded inaccuracy to limit wild points

5. Integrity - eliminating HMI, meetingrequired time to alarm


The Outline - What’s New?

Satellites Augmentations Summary of New Signals and Payoffs New Technology New Applications Cautions Conclusions


The Eras of Satellite NavigationFocus on the future

Pioneers -Transit

Deploymentand

Applications Development

2020201520102005200019951990198519801975197019651960

GPS Synthesis & Dev.Competition

IOC

GULF

D-1

IRAQ

Glonass

Augmentations – WAAS et.al.

Upgraded GPS +Galileo andGLONASS

“Robustening”

Our Focus


An Expanding GNSS World –Basic Satellite Systems

GPS

GLONASS (Russia)

Galileo (Europe)

QZSS (Japan)

Compass (China)


System Comparisons (courtesy Prof. Hein and Inside GNSS)


GPS Next Steps and Future


GPS Space Vehicle Comparisons

Category Block I Block II Block IIA Block IIR Block IIR-M Block IIF

SV Dry Mass444 Kg

(978 Lbs)

860 Kg

(1896 Lbs)

860 Kg

(1896 Lbs)

1039 Kg

(2291 Lbs)

1074 Kg

(2368 Lbs)

1453 Kg

(3204 Lbs)

EOL Power 410 W 710 W 798 W 1061 W 1061 W 2405 W

Design Life 5 years 7.5 years 7.5 years 10 years 10 years 12 Years

First Launch 22 Feb 1978 14 Feb 1989 26 Nov 1990 23 Jul 199720 May 2005

(Scheduled)

2006

(Scheduled)

Launch Vehicle Atlas E/F Delta II Delta II Delta II Delta II EELV (Both)

EC Nav Payload

(Signals)

L1 C/A, L1 P(Y),

L2 P(Y)

L1 C/A, L1 P(Y),

L2 P(Y)

L1 C/A, L1 P(Y),

L2 P(Y), L3

L1 C/A, L1 P(Y)

L2 P(Y), L3

L1 C/A, L1 P(Y),

L2 P(Y), L2 C,

L1 M, L2 M, L3

L1 C/A, L1 P(Y),

L1 M, L2 C,

L2 P(Y),L2 M,

L3, L5

May 2005 Q4 2008

L1 C/A, L1 P(Y), L1M, L2C,

L2 P(Y), L2M,L3, (+L5)

Our Focus


GPS Block IIR/IIRM Technical Specifications

Space Vehicle Weight• 1,039kg (2,291 lbs)

Launch Vehicle – Delta IIDesign Life – 10 YearsPayload Power

• Solar panels generate up to 1061 watts (EOL)Signals

• L1 C/A, L1 P(Y), L2 P(Y), L2 C/A, L1M, L2M, L3(+ L5)


GPS Block IIF Technical Specifications

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


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


Summary - Spectrum of Modernized GPS Signals

L5ARNS/RNSS Band

L1ARNS/RNSS Band

L2RNSS Band

P(Y)C/A

L2CM

L5

L1C

Earlier GPSDual Frequency w/Semi-codeless P(Y)

Block IIR-MLaunch 2005Dual Frequency

L1 C/A & L2C (+L5)

Block IIFLaunch 2008Three FrequencyL1 C/A, L2C, & L5

Block IIILaunch 2013

L1C, L2C, L5,& L1 C/A Code

L5

New!


GPS Satellite Status 9 July 07

168.512.06.9313.05.93II-A2265775

18.613.11.0526.09.05IIR-M28874174

39.005.04.0420.03.04II-R28190193

133.609.04.9628.03.96II-A2383332

158.728.03.9410.03.94II-A2302761

C

6.813.12.0617.11.06IIR-M29601125

164.728.09.9330.08.93II-A2277954

82.817.08.0016.07.00II-R26407283

128.401.10.9612.09.96II-A24320302

52.518.02.0329.01.03II-R27663161

B

180.824.03.9223.02.92II-A21890255

176.830.09.9209.09.92II-A22108274

114.718.12.9706.11.97II-A2503083

8.813.10.0625.09.06IIR-M29486312

166.920.07.9326.06.93II-A2270091

A

Active life(months)Input dateLaunch

dateTypeSCNORADPR

NSlo

tPlane

174.711.12.9222.11.92II-A2223116

173.105.01.9318.12.92II-A22275295

35.909.07.0423.06.04II-R28362234

113.231.01.9823.07.97II-R24876133

179.423.07.9207.07.92II-A22014262

78.910.12.0010.11.00II-R26605141

F

76.615.02.0130.01.01II-R26690184

130.815.08.9616.07.96II-A23953103

41.912.01.0421.12.03II-R28129222

85.201.06.0011.05.00II-R26360201

E

190.230.08.9104.07.91II-A21552246

163.522.11.9326.10.93II-A2287744

50.812.04.0331.03.03II-R27704213

90.203.01.0007.10.99II-R25933112

31.522.11.0406.11.04II-R2847421

D

Active life(months)Input dateLaunch

dateTypeSCNORADPRNSlotPla

ne

Total 30 Satellites Average Age 8.9 yrs.Standard Deviation 5.0 yrs. Oldest: operational 15.9 yrs – (Launched 4 July 1991)

Legitimate Concern for Future:Satellites 30 → 24 ??


GLONASS : Global Orbiting NavigationSatellite System (Russia)Nominally Comparable

to GPS.Orbit

• 64.8 deg inclination• 3 orbit planes• 19,100 km circular (8 day repeat track)

Design Life -1 to 2 years24 Active Satellites when Operational

Glonass - M


GLONASS : Global Orbiting NavigationSatellite System (Russia)

Accuracy: 50-70 meters C/A signals(10-20 meter accuracy military signals)

Spacecraft• 3-Axis stabilized, nadir pointing. Dual solar arrays.

Navigation signals (25 0.5625 MHz channels)• 2 bands: 1602.5625 - 1615.5 MHz & 1240 - 1260

MHz.• EIRP 25 to 27 dBW. -Right hand circular polarized.

Cesium clocks provide time accuracy to 1000nanoseconds.


GLONASS status on 9 July 2007(10 Operational Satellites – none older than 5 years)

27.806.02.0526.12.042412797068

18.207.10.0526.12.042413712057

25.708.12.0410.12.032404701016

switched off36.109.07.0613.02.0301.12.012382711075

41.129.01.0410.12.032403795064

59.504.01.0201.12.012381789123

switched off38.319.04.0702.02.0410.12.032402794012

26.506.02.0526.12.042411796071

I

NotesActive life(months)

OutagedateInput dateLaunch

dateCosmosNumber

GLONASS Number

FrequencyChannelSlotPlane

Comssing25.12.0624257160015

3.203.04.0725.12.0624247150414

2.703.04.0725.12.0624267170410

II

switched off8.809.07.0731.08.0625.12.0524187130224

8.931.08.0625.12.0524197140323

switched off46.507.02.0721.01.0325.12.0223947911022

49.831.01.0325.12.0223957920821

switched off17.409.07.0722.01.0625.12.0524177980319

switched off66.525.05.0705.01.0113.10.0023747831018

III


GLONASS Snapshot of Visibility


GLONASS the Future

Renewed Funding and Support by Russia

Apparently in negotiations with India

FDMA signal not as useful as CDMA• Notwithstanding, Combined GPS-GLONASS

receivers are important for impaired situations

• Apparently considering CDMA

Central Issue remains Satellite Lifetime andconstellation sustainability/affordability


EU Galileo Satellite Constellation

Constellation of 30 satellites in MEO• 27 active satellites - 3 spares• 23616 km height above earth• 1+2/3 revolutions/day• 56° inclination

Cost Saving setup ofGalileo constellation• Only 3 orbital planes compared to 6 with GPS• 3 Soyuz (2 satellites per launch) +

3 Ariane5 (8 satellites per launch)• Soyuz launches will be used during

the In-Orbit Validation (IOV) Phase

EADS-Astrium 2 0 0 3


Galileo – Technical Aspects


Galileo

Open Service (3 frequencies, free of charge)

Commercial Service (3-4 freq., not free, +integrity)

Safety of Life Service (airborne, railways etc.)

Public Regulated Service (security related, military)

Search and Rescue (compatible to COSPAS-SARSAT)

Galileo Services


Frequency Plan

MissionUplink

C1

5030 MHz5000 5010

GALILEO

OS + OS / SOL / CS CS / PRS

OS / SOL / PRS

GPS

1216 1240 1256

E3 E4

1260 1300 MHz

E6

12151164 1188

E5B L2 G2

GALILEOGALILEOGPS/ GALILEO

E5A / L5

GLONASS

1563 1587 1591 1610 MHz1559

E1E2 G1L1

GPS/ GALILEO GLONASS

Upper L-Band

Lower L-Band

C-Band

EADS-Astrium 2 0 0 3


First Galileo satellites

Contracts awarded in July 2003

GIOVE -A satellite

operational 12 Jan 2006 (by Surrey Satellite Technology Ltd (UK)

GIOVE A2 on contract as frequency insurance

EADS-Astrium (Munich) is building GIOVE – B (Launchdelayed to 2008?)


Looking Ahead - Galileo Galileo - operational 2013 – 2014 (?) Commercial Model evidently not Viable

• Difficult to compete with free resource World wide users will benefit from new

signals -Improved accuracy, higher reliability, better availability

Breakthrough: Instantaneous RTK through combination of GPS & Galileo

Agreement on Interoperability with GPS• But does this mean “Interchangeability?


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”


QZSS Orbit Constellation


QZSS Ground Track and Coverage


Original Planned Services of QZSS


QZSS Technical Capabilities

??


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


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


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.


Compass Operational Concept(A 2-way “active” system)

• 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

Consequences:

• Large, power-hungry equip.

• Location revealed

• Could institute user charges

• Limits on number of users


GPS has Fathered aNumber of Augmentations…

Ground Based• NDGPS (US) (Marine Beacons) + EDGPS (EU)

• LAAS (Future)• (eLORAN) decision soon??

Space Based• WAAS (Operational)• EGNOS• MSAS• GAGAN• Commercial

We will only touch on a few


European DGPS Beacons Corrections Broadcast

over marine beacons Similar to NDGPS (US) Accuracies typically 1-2

Meters Main Target is Marine

Users In US, congress

authorized at least 2beacons for each state


Wide Area AugmentationSystem (WAAS)

Safer Increased Capacity Cost Effective


WAAS Prototype Results -May 1999Vertical Accuracy - 3 Locations, 99.9% < 2.5m

Worst Accuracy of 100,000 Data points

was 7 MetersTypical Errors less than 2 feet


Japanese MSAS Status (similar to WAAS)


MSAS Performance

Typically 1 to 2meters 95%


Commercial Augmentations (OmniStar example)

Well established Worldwideservice

Partnered with GPSequipment manufacturers

Annual fee ~$1000 Oil Exploration and

Agricultural Markets XP: "better than 20 cms" &

HP: "better than 10 cms",95%CEP.

Would compete with GalileoCommercial services


-40 -30 -20 -10 0 10 20 30 40-30

-20

-10

0

10

20

30

East Error - m

North

Erro

r - m

Overall 95% accuracy 16.4 m

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


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


Real-Time Kinematic: Today

L1 Code and Carrier L2 Carrier Data Link

10 km10 km

2 cm accuracy2 cm accuracy


Galileo – How willRTK improve ?


GPS Satellite Visibility for RTK


GPS+Galileo Satellite Visibility for RTK


RTK Accuracy-some improvement with Galileo

1 Cm


Instantaneous RTK Reliability

1000 times betterfailure rate at 25 km


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


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


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


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?


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


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


Tracking Applications Have Proliferated

GPS is

the key


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


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


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 ?


Some Other Interesting Applications


Towards Auto-guided Automobiles

Vector KinematicRecievers

MEMS/IMURadarsCooperative Tracking

of other vehicles


And Perhaps the most Humanitarian:

Removing Unexploded Ordinance


A Caution:Three Critical Issues

for GPtS


GPS Applications have Proliferated

Military Civil

• Transportation- Aviation- Automobile- Maritime- Rail Control

• Public Services• Timing &

Frequency• Surveying• Surveillance• Other


We are Victims of our success:

GPS Enormous Capability

Worldwide DependencyWhat must we do to insure that the

Trust in GPtSis not misplaced?


THE “Big Five” Civil Goals for GPS

1. Assured Availability of GPS signals-Including impaired situations(mountains, urban areas, foliage, etc.)

• Number of GPS Satellites/Geometry• Interoperability and Standardization with Galileo et al

2. Resistance to Interference (RFI)• Additional Satellite RF power and Frequency Diversity• More jam resistant GPS receivers

3. Accuracy• Require Prediction Accuracy (Satellite Clocks and Age of Update)• Improved Satellite Geometry is essential• Augmentations: WAAS, LAAS,EGNOS, MSAS, NDGPS, PLs

4. Bounded inaccuracy to limit wild points• Concerned with the 1% or less “wild data points”• Good Satellite Geometry Coverage is Imperative

5. Integrity - eliminating HMI, meeting required time to alarm• WAAS• RAIM

Three of top four Goals are driven by the number of satellites –

hence DSB & IRT30+X satellite recommendation


GPS Issue #1 – (Availability)Constellation Sustainment

Average on-orbit life 8.9 years First IIF currently available for launch:

May 2008 First GPS III currently available for

Operations - April 2014

Needed: Sustained, high-level supportfor earlier GPS III delivery and availability

It is imperative the we avoid “GPS Brownouts”


Illustrating why current number of Satellitesis Minimal (Courtesy GPS World and John Lavrakas)

DOP is strongly driven by Masking Angle andnumber of satellites (the impaired user’s problem)

Above 10o, less than 30 satellites destroysaccuracy and availability

Monthly Availabilityof 24 sats 92 to 100%

DOP vs. Mask Angle (degrees)

The Knee


GPS Issue #2 –GPS Robustness (Deterrence)

Constellation size of 30+X for users inimpaired environments (the GDOP imperative)

Affordable GPS Receiver InterferenceRejection Technology (inertial integration anddigital beam steering technology)

GPS Backup – Loran?

Need: Full, urgent Commitment by US

Needs full development

Needs decisions


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


As providers of GtPS

we must insure the Service

is Always Available - To meet:

the Safety, Economic, and Convenience

Needs

of the World


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

Limited only by Imagination!

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