GPS, GLONASS, Galileo, BeiDou, · 2020. 4. 5. · Multi-GNSS Future: GPS, GLONASS, Galileo, BeiDou, … Pratap Misra. Sogei Workshop . GNSS Technology Advances in a Multi-Constellation

Multi-GNSS Future:

GPS, GLONASS, Galileo, BeiDou, …

Pratap Misra

Sogei Workshop GNSS Technology Advances in a Multi-Constellation Framework

Rome, April 22-23, 2013

Source: International Committee on GNSS (ICG)

© 2013 Pratap Misra

GNSS Global Satellite Navigation System

• Originally defined by the International Civil Aviation Organization (ICAO) as: “a worldwide position and time determination system

that includes one or more satellite constellations, aircraft receivers and system integrity monitoring, augmented as necessary to support the required navigation performance for the intended operation”

• GNSS = a satellite navigation system • All GNSSs follow the GPS model

2


Multi-GNSS Future* Outline

• Why Do We Need So Many Systems? • GNSSs Under Development:

– Global Systems: GPS III, GLONASS, Galileo, & BeiDou

– Regional Systems: Japan’s QZSS, India’s IRNSS

– Regional Augmentations: US’ WAAS, NDGPS; Europe’s EGNOS; Japan’s MSAS; Russia’s SDCM; India’s GAGAN

• Coexistence: Compatibility • Cooperation: Interoperability • Competition: Who will be Number 1?

3 * Opinions of the author alone


GNSS Status • 75 working satellites in early 2013

– GPS: 31 – GLONASS: 24 – Galileo: 4 – BeiDou: 16

• 5-7 Launches Scheduled in 2013: 2 GPS IIFs; 2 Galileo; 1 GLONASS-K

• Only GPS is operational and in > 1 billion mobile devices – market expected to grow to 5 billion

• 4 operational systems with 120 satellites in 2020

4

Source: ICG-7 presentation by Dr. Lu Xiaochun


It’s Not Just About Navigation, It’s About Economics & Politics

• Sovereignty • National Pride • Markets & International Trade

– Brand Building, Consumer Confidence • Standards & Certification • Intellectual Property & Patents • Military Use & National Security

5

Source: ICG

GNSS Users’ Perspective

6 Source: GPS SPS PS, 2008


Performance Metrics My System is Better than Yours

• Accuracy • Availability of Service • Integrity (or Reliability)

– Can I count on my position estimate to be ‘correct’? • Robustness

– Can the system withstand ‘small’ disturbances? • Security • Challenge:

– Deliver service like a utility: water or power supply – Rigorous, constant maintenance: No screw ups!

7


GPS has Set High Standards

• Delivers a lot more than promised – Near flawless performance over 20 years

• Made it Look Easy • A Victim of its Own Success?

– Satellites last for ever, no screw-ups – No urgency in Washington re budgets?

• Success Breeds Imitators • Can GPS Remain #1 ?

– Remains to be seen: The race is GPS’ to lose – Not sitting still

8


9

GPS Modernization

• Space Segment – Cross links among satellites, flexible power, spot beam,

integrity monitoring – Additional, more capable military signals: M-code on L1

and L2 – Additional, more capable civil signals: L2C, L5, L1C

• Control Segment – Block II OCS OCX to fly new spacecraft – Distributed architecture, security

• User Segment – MGUE (Mil. GPS User Equip’t): Enhanced A-J, A-S, A-T – New security architecture: SAASM Pronav – New paradigm: from ‘form-fit’ military receivers to GPS

chipsets

GPS III satellite Source: Lockheed

10

GPS Signal Modernization

C/A Code • Civil Use • Degraded

P(Y) Code • Encrypted


1227.6 MHz (L2)

1575.42 MHz (L1)

(2 May 2000)

M-Code (Starting 2005)


Misra 2010

Civil Signal (Starting 2010)

L2C-Code (Starting 2005)

1176.45 MHz (L5)

L1C (2014)

Direct Sequence Spread Spectrum

11

×

×

=

carrier

spread spectrum waveform

Tc

Td data waveform

modulated spread spectrum signal

T0

f0 = 1/T0 = carrier frequency (Hz) Rc = 1/Tc = chipping rate (chips/s) Rd = 1/Td = data rate (bits/s)

Source: Dr. Chris Hegarty, MITRE

Binary Offset Carrier Modulation

×

×

=

×

Carrier

Spreading code

Square wave

Data

BOC signal*

*Shown at baseband (i.e., without carrier)

Tsq

Fsq = 1/Tsq = subcarrier frequency (Hz)

12

Source: Dr. Chris Hegarty, MITRE

13

Evolution of GPS Signals

1176.45 MHz

Block II / IIA / IIR 1989 - 2005

Block IIR-M Starting in 2005

Block IIF Starting in 2010

1227.6 MHz 1575.42 MHz

C/A

P(Y)

M L2C M

P(Y)

L1 L2 L5

14

> $1b award to LMC in 2008

> $1b award to Raytheon in 2009

15


16

Global’naya Navigatsionnaya Sputnikovaya Sistema

GLONASS • History

– Developed by Soviet Union, first launch: 1982 – Declined under Russia, but now revived – Have launched 81 satellites so far

• Constellation – 24 satellites in 3 orbital planes, 64.8º inclination – 19,100 km altitude, 11 ¼ hour period

• Signals – 3 allocated bands: G1 (1602 MHz), G2: (1245

MHz), G3 (1202 MHz) – C/A-like code: 511 chips, 1 ms code period, 50

bps data – All SVs use same PRN with frequency division

multiple access (FDMA) using 16 frequency channels, reused for antipodal SVs

GLONASS Constellation Source: ROSCOSMOS

17

Soviet-built GLONASS Aviation Receiver & Tool box (circa 1990)

ASN-16


GLONASS Status & Plans

• 24 working satellites in 2013 • New satellites GLONASS-K and

GLONASS–K2 under development • CDMA signal planned • No significant user base

18

GLONASS-M

GLONASS-K

Source: ROSCOSMOS

19

Galileo • Jointly financed by EC and ESA • “Seen” as a civil system, but

military role may emerge • 5 Services being considered

– Free: Open Service – For a Fee :

• Commercial Service • Safety-of-Life Service • Public Regulated Service • Search & Rescue Service

• 30 MEOs in 3 planes inclined at

56° • First experimental satellite

launched in 2005

Source: ESA


Galileo Status & Plans

• 4 in-orbit validation (IOV) satellites (launched in 2011 & 2012)

• Ground infrastructure (monitor stations & control centers) capable of generating navigation messages

• First 3-D positioning demonstrated at ESTEC (March 12, 2013)

• Plans – First full-operational capability (FOC)

satellites to be launched in 2013 – 18 FOCs in orbit in 2014

• Budget of €7.9 billion for deployment & exploitation (2014-2020) under discussion

20

Source: ESA


21

Etymology of BeiDou

• BeiDou (北斗)* – Bei: North/Northern

– Dou: a traditional Chinese container used for measuring grain by volume

– BeiDou: Big Dipper constellation • Ladle • Butcher’s cleaver • Drinking gourd • Coffin & mourners • Charles’ wain

*Courtesy of Dr. Grace Gao, Stanford University

Source: Wikimedia


22

BeiDou/Compass

• Chinese • Beidou -- 1

– Regional system – 3 GEOs orbited in 2000 – 2003 – ‘Active’ system

• Beidou-- 2 or Compass – Global system (under

development) – Plan: 5 GEOs, 27 MEOs, 5

IGSOs


BeiDou Status & Plans

• Constellation: 5 GEOs, 5 IGSOs, 4 MEOs • Regional (Asia/Pacific) system operational • Launched 16 BeiDou-2 satellites since 2007,

No launches in 2013 • Released an ICD for B1 open service SIS in

2012 • Plans:

– Final constellation: 5 GEOs, 3 IGSOs, 27 MEOs

– 40 more satellites to be launched – Operational:2020

23


Marketing a GNSS: You’d Like Our System Better!

– Protecting Domestic Markets, Finding Foreign Markets

– Balance between open trade and Protectionism

– Regulation (A Little Arm Twisting) • Russia’s plan to “require” GLONASS in civil aircraft operating in

its airspace; import tariffs on GNSS receivers that don’t include GLONASS

• China’s plan to “require” transportation operators to use BeiDou

– Political Muscle • Russia agreement with India to promote GLONASS adoption

24

Marketing GPS-1

25

http://gps.gov

http://gps.gov/

Marketing GPS-2

26

http://gps.gov

http://gps.gov/

Marketing GPS-3 Is This the Best of Madison Avenue?

27

Marketing Galileo

28

http://gsa.europa.eu/galileo

http://gsa.europa.eu/galileo

Marketing GLONASS

29

www.glonass-ianc.rsa.ru

http://www.glonass-ianc.rsa.ru/

Marketing BeiDou

30

www.beidou.gov.cn

http://www.beidou.gov.cn/

Case for QZSS-1

31 Source: A presentation by Japan at the ION GNSS 2008 in Savannah, Georgia, on 17 September 2008

Case for QZSS-2



QZSS Status

• 3 satellites planned in highly elliptical 36,000-km altitude orbits

• First satellite launched in 2010

33 Source: JAXA


IRNSS Indian Regional Navigation Satellite System

• 3 GEOs, 4 IGSOs • First launch: any day

34

Source: ISRO


Multi-GNSS Future* Outline

• Why Do We Need So Many Systems? • GNSSs Under Development:

– Global Systems: GPS III, GLONASS, Galileo, & BeiDou

– Regional Systems: Japan’s QZSS, India’s IRNSS

– Regional Augmentations: US’ WAAS, NDGPS; Europe’s EGNOS; Japan’s MSAS; Russia’s SDCM; India’s GAGAN

• Coexistence: Compatibility • Cooperation: Interoperability • Competition: Who will be Number 1?

35 * Opinions of the author alone


Coexistence & Cooperation among GNSSs

36

• Coexistence: Compatibility Living peacefully with others despite fundamental

disagreements

• Cooperation: Interoperability Working together for a common purpose

Coexistence: RF Compatibility Spectrum Allocations

37

GPS GLONSS GPS

L2 L1

1240 1216 1563 ~ ~ 1587 MHz

L-Band: 1 GHz – 2 GHz

LF MF HF VHF UHF SHF

30 kHz 300 kHz 3 MHz 30 MHz 300 MHz

3 GHz

GPS

Radio Spectrum

Coexistence: RF Compatibility Spectrum Allocations

38

Galileo GPS

L5, E5A

Galileo GPS GLONASS Galileo Galileo GPS

E5B L2 G2 E6 E2 L1 E1

1164 1188

1215

1240 1256

1260

1300

1559

1216 1563

~ ~

G1

1593

GLONASS

1610

1587 MHz

L-Band: 1 GHz – 2 GHz

LF MF HF VHF UHF SHF

30 kHz 300 kHz 3 MHz 30 MHz 300 MHz

3 GHz

GNSS

Radio Spectrum

Coexistence: RF Compatibility GPS, GLONASS, & Galileo Fill Upper L-Band

39

Source: ?

GNSS Signal Plans

40

Future CDMA signal

SBAS (US Europe

India Japan)

QZSS (Japan)

IRNSS (India)

COMPASS (China)

Galileo (Europe)

GLONASS (Russia)

GPS (US)

L1 L5 L2

Compass & IRNSS In S-band

1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300 Frequency (MHz)

Source: Dr. John Betz, MITRE


Coexistence: Political Compatibility

• Galileo’s erstwhile plans to broadcast over the M-code frequencies

• BeiDou’s current plans to broadcast over Galileo’s PRS code

41


Cooperation: Interoperability The More Systems, The Better

• Common time standard: UTC – Each GNSS uses its national time standard – Transmit biases among national standards

• Common coordinate frame: ITRF – Each GNSS uses its reference coordinate frame – Establish transformations among coordinate frames

42

GPS + GLONASS + Galileo in 2013

43 Source: Curran-Petovello-Lachapelle, GPS World, April 2013

U.N. is on the Job

44

http://unoosa.org/oosa/en/SAP/gnss/icg.html

45


GPS III • Next generation satellites

– First launch anticipated ~2014

• Potential Block III features (to be phased in incrementally): – New L1 civil (L1C) signal – Increased levels of accuracy, availability, reliability, and integrity – High-speed uplink/downlinks/cross-links – “Spot beam” for military M-code signal

• Longer pseudorandom codes for open signals – Improves cross-correlation performance

• Data-less (pilot) components – Portion of signal energy devoted to component with no navigation

data modulation – Enables more robust tracking

• Advanced modulation schemes – Binary offset carrier and variants

• Robust forward error correction – Convolution encoding, low-density parity check

• More precise navigation data

46

Hegarty


Spectrum Sharing Considerations

• All systems recognize the need for Radio Frequency Compatibility – Technical details for assessment and acceptance still being worked

• Increasing recognition of National Security Compatibility for military or authorized signals – Pioneered by GPS for M code signal – Mimicked by Galileo for PRS – Accepted by IRNSS – Still being discussed with GLONASS and COMPASS

• Interoperability of civil signals with GPS civil signals viewed as benefitting everyone – New systems become useful even with only a few satellites launched – GPS remains the world standard as others mimic it – Users obtain better geometry and availability from more satellites

47


QZSS Status

• 3 satellites planned in highly elliptical 36,000-km altitude orbits

• First satellite launched in 2010

48 Source: JAXA


IRNSS Indian Regional Navigation Satellite System

• 3 GEOs, 4 IGSOs • First launch: any day

49

Source: ISRO

50

GPS III Source: Lockheed-Martin.

51


GPS Modernization

• First announced in 1998 by Vice President Gore – Additional civil signals

• More – and More Capable – Signals – Civil signals: from 1 to 4 – Military signals: from 2 to 4

• “Classic” GPS Modernized GPS GPS III • 2005 was the Year of Transition

– First GPS Block IIR-M satellite launched – An additional civil signal: L2C – Additional military signals on L1 and L2: M-codes

• GPS III to be completed ~ 2020

52


53

GPS Modernization

• Space Segment – Cross links among satellites, flexible power, spot beam,

integrity monitoring – Additional, more capable military signals: M-code on L1

and L2 – Additional, more capable civil signals: L2C, L5, L1C

• Control Segment – Block II OCS OCX to fly new spacecraft – Distributed architecture, security

• User Segment – MGUE (Mil. GPS User Equip’t): Enhanced A-J, A-S, A-T – New security architecture: SAASM Pronav – New paradigm: from ‘form-fit’ military receivers to GPS

chipsets

The current Hand-Held Military Receiver Suffers in Comparison to Civil

Counterpart

54

• Comm: voice, email/text message • Positioning: GPS, Wi-Fi, cell towers • Camera: geo-tagged pictures • Social networking: Where other iPhones are • … • Lost iPhone

DAGR

Hand-Held Military Receiver Suffers in Comparison to Civil Counterpart

55

DAGR

Common GPS Module (CGM)

Enablers Build “Engines” + =

Integrators Build Applications

Global GPS Use

Commercial Method (GPS “engines” enable multiple applications)

Proposed MGUE Approach (Emulate commercial, Build the engine!)

GPSW Builds Enabling “Engines” + =

Integrators Build Applications

Global Military GPS Use

Common GPS Module (CGM)

GPS Has Raised Expectations

57

Instantaneous, meter-level position estimates EVERYWHERE Performance metrics: accuracy, continuity, integrity, availability Intense research focus on multi-sensor navigation


Current Navigation Challenges Multi-Sensor Navigation

• Open interface standards for plug-and-play sensors • Software architectures to accommodate re-configuration of

sensors • Dynamic calibration/characterization of sensors of diverse

quality • Kalman-type filters to process asynchronous data from

changing sensors of diverse quality New Technologies

• Better MEMs sensors, Atomic reference mass accelerometers & gyros (“cold atoms interferometry”)

• Chip-scale atomic clocks (CSACs) • Inertia of elastic waves/self-calibration/3-D fabrication

58

Ohio State Univ. photo

59


60

BeiDou/Compass

• Chinese • Active system

– 2 - 3 geostationary satellites orbited in 2000 – 2003

– I MEO launched in 2007 • Mission: unclear • (08/15/2011) four geostationary

satellites, a medium earth orbiting spacecraft, and the four IGSO satellites now on orbit.


61

Implications of Foreign GNSSs for GPS

• Technical – Compatibility and Interoperability

• Political – Sovereignty, national pride, – Who is #1?

• Economic – Commercial activity, technical innovation

• Military – Complicates Navwar issues:

• Protect U.S. military use • Prevent hostile use, • Preserve civil use (outside the area of military ops)


62

Satellite Navigation Overview Outline

• Principles of Satellite Navigation

• GPS Overview: System, Signals and measurements, Performance

• Applications and Performance Metrics • Potential Partners/Rivals: GLONASS,

Galileo, BeiDou/Compass, …

Frequency Plans

Frequency Plans*

*Adapted from T. Grelier et al., Inside GNSS, May/June 2007

Frequency Plans*

*Adapted from T. Grelier et al., Inside GNSS, May/June 2007 65


66

GLONASS • History

– Developed by Soviet Union, first launch: 1982 – Declined under Russia, but newly revived – Similar to GPS: Passive, one-way ranging – 10-12 working satellites over the past 5 of years, currently 16 – No significant user base


• Signals – 3 allocated bands: G1 (1602 MHz), G2: (1245 MHz), G3 (?) – C/A-like code: 511 chips, 1 ms code period, 50 bps data – All SVs use same PRN with frequency division multiple access

(FDMA) using 16 frequency channels, reused for antipodal SVs • Plans: 18 SVs in 2008, full constellation in 2011 (?)

67

GPS+GLONASS Satellite Visibility

Misra/1997

HDOP VDOP

2 3 4 5 6

Dilution of Precision (DOP) 1 0

99.999 99.99

99

95 90

50

30

10

1

0.1

0.01

GLONASS-21 GPS+GLONASS (2x21)

10 9 8 7

GLONASS-21 GPS+GLONASS (2x21)

Prob

abili

ty (%

)

Prob

abili

ty (%

)

50 30

10

1

99.9

70

4 6 8 10 12

Satellites Visible 2 20 18 16 14

68

GPS & GLONASS Position Estimates* 1-Minute Samples, 15 June 1996

69

GPS & GLONASS Position Estimates* 1-Minute Samples, 15 June 1996


70

BeiDou/Compass

• Chinese • BeiDou: Regional System

– Active system – 2 - 3 geostationary satellites

orbited in 2000 – 2003 • Compass: GNSS

– 1 MEO launched in 2007 •


71

Summary: Take-Away Points • Satellite navigation systems exploit basic properties of radio waves:

Transit exploited the Doppler effect, GPS exploits the known speed of propagation

• GPS is based on the old idea of trilateration, but implemented with the technology of the second-half of the 20th century: space-based radio transmitters, ultra-stable clocks, and spread spectrum signals

• A GPS receiver measures pseudoranges to the satellites by measuring pseudo-transit times of radio signals. It takes 4 satellites (i.e., 4 pseudoranges) in order to estimate position (x, y, z) and time t

• With a clear view of the sky, it’s easy to get positioning accuracy of several meters with a $100 GPS receiver, or relative positioning accuracy of millimeters with a pair of $1000 receivers.

• GPS satellites are 20-watt transmitters 20,000 km away, so the signals reaching the earth are very weak and, therefore susceptible to interference.

• The success and breadth of GPS applications is attributable largely to “the chip.” The VLSI revolution was well-timed for GPS


GPS Modernization

• First announced in 1998 by Vice President Gore – Additional civil signals

• More – and More Capable – Signals – Civil signals: from 1 to 4 – Military signals: from 2 to 4

• “Classic” GPS Modernized GPS GPS III • 2005 was the Year of Transition

– First GPS Block IIR-M satellite launched – An additional civil signal: L2C – Additional military signals on L1 and L2: M-codes

• GPS III to be completed ~ 2020

72

73

GPS Signal Modernization

C/A Code • Civil Use • Degraded



1227.6 MHz (L2)

1575.42 MHz (L1)

(2 May 2000)



Misra 2010

Civil Signal (Starting 2010)

L2C-Code (Starting 2005)

1176.45 MHz (L5)

L1C (2014)


74

Galileo GPS

L5, E5A

Galileo GPS GLONASS Galileo Galileo GPS

E5B L2 G2 E6 E2 L1 E1

1164 1188

1215

1240 1256

1260

1300

1559

1216 1563 ~ ~

G1

1593

GLONASS

1610

1587


75

GLONASS • History

– Developed by Soviet Union, first launch: 1982 – Declined under Russia, but now revived – Similar to GPS: Passive, one-way ranging – 22 working satellites in March 2011 – No significant user base


• Signals – 3 allocated bands: G1 (1602 MHz), G2: (1245 MHz), G3 (1202 MHz) – C/A-like code: 511 chips, 1 ms code period, 50 bps data – All SVs use same PRN with frequency division multiple access

(FDMA) using 16 frequency channels, reused for antipodal SVs • Plans: full constellation in 2011, evolving capability as CDMA

signals are added <www.glonass-ianc.rsa.ru>

76

Soviet-built GLONASS Aviation Receiver & Tool box (circa 1990)

ASN-16


77

Summary: Take-Away Points • GPS is based on the old idea of trilateration, but

implemented with the technology of the second-half of the 20th century: space-based radio transmitters, ultra-stable clocks, and spread spectrum signals.

• The success and breadth of GPS applications is attributable largely to “the chip.” The VLSI revolution was well-timed for GPS.

• A GPS receiver measures pseudoranges to the satellites by measuring pseudo-transit times of radio signals. It takes 4 satellites in view (i.e., 4 pseudoranges) in order to estimate position (x, y, z) and time t

• With a clear view of the sky, it’s easy to get positioning accuracy of several meters with a $100 GPS receiver, or relative positioning accuracy of millimeters with a pair of $1000 receivers.

• GPS satellites are 30-watt transmitters 20,000 km away, so the signals reaching the earth are very weak and, therefore susceptible to interference.

78

GNSS = A Satellite Navigation System

79


• Compatibility – Radio Frequency Compatibility:

no harmful interference among signals

– National Security Compatibility: spectral separation between GPS civil signals and other systems’ signals, and M code

• Interoperability – Two systems are better than

one – Requires attention to signal

designs, system performance, and coordinate frames and time references

Compatibility & Interoperability of Radionavigation Systems

80

Source: Unknown

81

82

83

84

85 Source: A presentation by Japan at the UN International Committee on GNSS Expert Meeting in Montreal on 15 July 2008


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GPS, GLONASS, Galileo, BeiDou, · 2020. 4. 5. · Multi-GNSS Future: GPS, GLONASS, Galileo, BeiDou, … Pratap Misra. Sogei Workshop . GNSS Technology Advances in a Multi-Constellation