QUO VADIS? Where are we going in Satellite Navigation?web.stanford.edu/group/scpnt/pnt/PNT10/presentation_slides/3-PNT...QUO VADIS? Where are We Going in Satellite Navigation? Guenter

QUO VADIS? Where are We Going in Satellite Navigation?

Guenter W. HeinHead

of Galileo

Operations

and Evolution

DepartmentEuropean

Space

Agency

PNT Symposium, Stanford, CA, USA, 9 Nov

2010

QUO VADIS? | Guenter W. Hein | Stanford’s PNT, CA, USA | 09/11/2010 | Slide 2

OVERVIEW

•

Systems and Architectures

•

Frequencies, Signals and Generation

•

Clocks

•

Receivers

•

Interference and Security in GNSS

•

Conclusions


CURRENT AND PLANNED SATELLITE NAVIGATION SYSTEMS

GlobalGPS

Galileo

GLONASS

COMPASS

RegionalQZSS

IRNSS

AugmentationWAAS EGNOS

MSAS GAGAN

SDCM MASS

GINS (?)


SYSTEMS AND ARCHITECTURES

•

Large number of GNSS satellites in visibility in future

•

The users will pick up the best GNSS signals based on:

Power level

Easy acquisition

Adherence to multi-constellation standards


THE MORE SATELLITES THE BETTER?

GalileoGPS GLONASS

GalileoGPS

Galileo

COMPASSGLONASS

GPSGalileo

COMPASSGLONASS

GPSGalileo

GINS

?


SBAS FUTURE: FROM SINGLE TO DUAL FREQUENCY

SBAS (EGNOS + WAAS + MSAS)

GPS Single Frequency

SBAS (EGNOS + WAAS + MSAS) GPS Dual Frequency

SBAS (GPS L1 only) SBAS (GPS L1 + GPS L5)

LPV-200

1 2


EGNOS + WAAS + MSAS + GAGAN + SDCM (GPS Dual Frequency)

+ 10 RIMS/SBAS in Southern Hemisphere

EGNOS + WAAS + MSAS + GAGAN + SDCM

(GPS Dual Frequency)

3 4

SBAS FUTURE: MULTI-REGIONAL/DUAL FREQUENCY


5 SBAS (GPS + Galileo Dual Frequency)+ RIMS in Southern Hemisphere

Almost global- except polar regions - LPV-200 availability

SBAS FUTURE: MULTI-REGIONAL/FREQ/SYSTEM

5


CAT-I L1/L5 GPS + GAL

Ava

ilabi

lity

for H

AL:

40m

VA

L:10

mM

inim

um D

epth

of C

over

age:

5

< 50%

> 50%

> 75%

> 85%

> 90%

> 95%

> 99%

> 99.5%

> 99.9%

Longitude (deg)

Latit

ude

(deg

)

L1/L5 Service / 24 GPS + 27 Galileo satellites / GEOs set to monitored / RIMS Elevation Mask 15deg / MT28 ImplementedTimestep 300s / Duration 10 days / Gridsize 2.5x2.5deg

-180 -120 -60 0 60 120 180-90

-60

-30

0

30

60

90


ARCTIC COVERAGE STUDIED IN EGEP

•

Cooperation with Canadian Space Agency on definition of navigation payload on Polar Communication & Weather (PCW) HEO Molniya type satellites

•

With only a few more RIMS LPV- 200 service can be guaranteed in the Arctic

•

Alternative orbit options like IGSO to be studied in detail as well. Artemis could be (test) candidate (re-use similar to Chinese CAPS system)

•

Option of generative payload kept open

EGNOS /PCW LPV-200 GPS L1/L5 Availability

with +10 RIMS in Arctic

Artemis visibility


OVERVIEW

•


•


•

Clocks

•

Receivers

•


•

Conclusions


•

Compatibility refers to the ability of space-based positioning, navigation, and timing services to be used separately or together without interfering with each individual service or signal, and without adversely affecting national security

•

Interoperability refers to the ability of civil space-based positioning, navigation, and timing services to be used together to provide better capabilities at the user level than would be achieved by relying solely on one service or signal

COMPATIBILITY & INTEROPERABILITY

*NSPD-39: U.S. Space-Based Position, Navigation, and Timing Policy December 15, 2004


INTEROPERABILITY TODAY

Interoperability achievedInteroperability still to be achieved


•

All superpowers have or aim at their own navigation system

•

However: RNSS bands extremely scarce

RNSS portion of Radio Frequency (RF) spectrum congested

•

Especially for E1/L1 band

Bands suitable for RNSS usage very limited!

GPS

Galileo

COMPASS

QZSS

GLONASS (potentially)

CONGESTION OF E1/L1 BAND


•

Modernization of existing systems

•

Deployment of new systems

•

Intersystem interference is becoming an issue

Particularly for authorized services

Spectral separation plays a fundamental role

But also for open services

Galileo, GPS, Compass, QZSS, GLONASS (potentially) will provide interoperable signals increasing the noise floor and the consequent degradation of performance

•

L-Band may not serve all users in an ideal way (indoor/single frequency/ iono)

Spectral resources get scarce

NEW SIGNALS AND FREQUENCY BANDS MOTIVATION


•

ITU Allocation for C-Band (5010-5030) available for RNSS since WRC 2000

•

Technical difficulties and limitations in performance for that allocation–

C-band allocation adjacent to mission up-link (stop band required)

–

Narrow bandwidth (only 20 MHz minus stop band, say 15 MHz)

•

Advantages of C-

Band–

Higher resolution

–

Smaller ionospheric

impact

–

Smaller antennas at satellite

•

Drawbacks of C-Band–

Higher attenuation in atmosphere

–

Higher power at satellite or user array antennas needed

•

Studies indicate that C-band for GNSS mass market is not (yet) mature

•

C-band preferable for high-power signals and smaller antennas

•

Search for more bandwidth on C-band necessary

C-BAND DOWN-LINK FREQUENCY


•

S-Band (2483.5 –

2500 MHz) is RNSS regionally (Asia/America)

•

ITU allocation for S-Band (2483.5-2500 MHz) in Europe on agenda of WRC 2012

•

S-Band already successfully used by Chinese Beidou

since 2003

•

Indian IRNSS/GINS announced to provide navigation service in S-Band

•

S-Band already used today for communication (WLAN/Bluetooth)

•

Advantage: Synergies between navigation and communication (same front-end)

•

Disadvantage: Harsh interference environment expected

Clarity needs to be gained on the added value of combining navigation and communication in S-Band for mass market – Mission Definition

S-BAND DOWN-LINK FREQUENCY

• ITU divides world into three regions for radio spectrum management

• Region 1 • Europe, Africa, Middle East, west of the Persian

Gulf, Russia• Region 2

• American continent, some eastern Pacific Islands• Region 3

• China, Japan, East Asia and most of Oceania


ADVANCED ON-BOARD CLOCK MONITORING & CONTROL UNIT

•

To improve the stability of the on-board frequency reference and reduce its frequency jumps

•

Generates clock signal as weighted average/ensemble of all clocks rather than relying on the signal of one single master clock

DADEV Freq Jump

DADEV (2)

DADEV (3)

IEM

1x̂ D aa

Kalman Filter

Pre-processing „Laboratory Conditions“

DADEV Freq Jump

DADEV (2)

DADEV (3)

IEM

1x̂ D aa

Kalman Filter

Pre-processing „Laboratory Conditions“

Clocks Average Output signal


•

To detect signal integrity anomalies (e.g. evil waveforms) on-board and trigger alerts in real-time simplifying ground integrity checks

•

Exploits high signal-to-noise ratio available on-board

•

Signals could be monitored before transmitting antenna (1) or after that (2)

ON-BOARD SIGNAL MONITORING

Signal generationClockCoupler

Signal monitoring unit(correlator, signal measurements)Alerts

Antenna

Probeantenna

1

2

Payload

Monitoring equipment


SELF-EQUALISATION DEVICE

•

To measure signal distortions (e.g. spectrum, group delay) and generate corrections to signal generation parameters

•

Exploits high signal-to-noise ratio available on-board

•

Correction loop not necessarily in real-time (e.g. could be via ground command), as observed signal distortions are slowly drifting (hours)

ClockCoupler

Antenna

Payload

Self-Equalisation Device

Frequency generation,amplification, multiplexing

Navigation signalgeneration

Correction loop


•

To improve the ground sensor stations tracking performance, especially in presence of multipath and interference

•

Antenna array and receiver processing allow satellite tracking with narrow beams, keeping multipath and interference out, resulting in better performance and robustness of orbit determination

ADVANCED GROUND SENSOR STATIONS W/ BEAM-FORMING

Antenna array

MultipathInterference


•

Evolution in signal structure was driven in the past by

Higher accuracy, spectral separation and spectral shaping

•

Future signals shall comply with stringent spectral requirements

IMPROVEMENT OF SIGNAL CHARACTERISTICS

•

Complexity versus performance figures such as TTFF

Time to Acquisition (TTA)

Time for data demodulation

→

Need to investigate on ways to reduce TTA and time for data demodulation

Help Navigation signals could support fast acquisition

Separate, dedicated low chip rate signal

Flexibility of data message

Embedding of variable content part in addition to fixed one

Combination of the data information at symbol level instead of bit level


CURRENT AND FUTURE PAYLOADS

CURRENT FUTURE


•

On-Board Integrity Monitoring

Lower requirements on ground segment and/or user segment

•

Inter-satellite Links

Intra-system communications

Inter-satellite ranging

Autonomy

•

SBAS payloads

From transparent to generative

REBALANCE OF COMPLEXITY: GROUND TO USER SEGMENT


INTEGRITY – WHERE FROM ?

GNSS ?

SBAS ?RAIM ?


GIC / RAIM OPTIONS

•

Relative RAIM (RRAIM) relaxes TTA, but limited to GIC (GNSS Integrity Channel) performance; still requires GEO transmission

•

Absolute RAIM (ARAIM) method proposed by FAA; based on multiple solution separation; still needs:

Prototyping on real data

Threat analysis

Message consolidation

Satellite failure rate definition

•

Note: ARAIM only works with 30 or more satellites -> multi– constellation seems to be solution

RRAIM Concept

ARAIM PLs (URA 1m, bias 0.5m, GPS/Gal fail 10-4/7)


ARAIM RESULTS FOR 30 SVS URA = 0.5 m

For VAL = 35m, NDP & Acc: 97.77% coverage at 99.5% availability< 50% > 50% > 75% > 85% > 90% > 95% > 99% >99.5% >99.9%

Longitude (deg)

Latit

ude

(deg

)

URA = 0.5m, Bias = 0.5m, URE = 0.25m, rBias = 0.1m

-150 -100 -50 0 50 100 150

-80

-60

-40

-20

0

20

40

60

80

99.5% VPL - 20.46 m avg., 35m avail = 99.99%< 15 < 20 < 25 < 30 < 35 < 40 < 45 < 50 > 50

Longitude (deg)

Latit

ude

(deg

)

URA = 0.5m, Bias = 0.5m

-150 -100 -50 0 50 100 150

-80

-60

-40

-20

0

20

40

60

80

ARAIM currently predicted upon a user update rate of ~ 1hour

Reference: Eldredge, Satellite-Based Augmentation System (SBAS) Integrity Services, ICG WG-B, Munich, March 8, 2010

GPS


OVERVIEW

•


•


•

Clocks

•

Receivers

•


•

Conclusions


Potential Future Technologies

For reference (Galileo)

For reference (GPS)

FUTURE TECHNOLOGIES

y (1sec) y (104sec) mass volume power

RAFS 5x10-12 5x10-14 3.2 kg 2.5 litres 30 W

PHM 1x10-12 1x10-14 19 kg 29 litres 60 W

Mini PHM 1x10-12 1x10-14 12 kg 15 litres 40 W

Caesium 3x10-12 1x10-14 10 kg 12 litres 30 W

Laser pumped RAFS

1x10-12 1x10-14 3.5 kg 3 litres 30 W

Cold Atoms /

Trapped Ions5x10-13 5x10-15 3.5 kg 3 litres 30 W

GPS RAFS 2.5x10-12 5x10-15 6.2 kg 4.8 litres 30 W

GPS and GIOVE


• Transfer of stable frequency GEO to GNSS (MEO)–

Two-way links and master clock(s) in the GEO▫

Real time

▫

Does not require clock/ambiguity parameters for orbit determination

–

Ultra stable oscillators in MEO

–

Cancellation of first order Doppler

–

Real time frequency dissemination

–

Steering of GEO frequency from the ground

• Time System–

Reference time frame in space (independent of earth)

FREQUENCY & TIME DISSEMINATION VIA GEO


OVERVIEW

•


•


•

Clocks

•

Receivers

•


•

Conclusions


SEVEN TECHNOLOGY ENABLERS FOR CONSUMER GPS

Technology Consequence

A-GPS Faster, longer, higher

Massive Parallel Correlation Longer, higher with coarse-time

High Sensitivity Small, cheap antennas

Coarse Time NavigationFast TTFF without periodic

wakeup

Low TOW Decode time from weak signals

Host-based GPS Single die

RF-CMOS

* F. van Diggelen: A-GPS Assisted GPS, GNSS, and SBAS, Artech House, 2009


RECEIVER PLATFORMS

Card1995

SoftwareCode

> 2010Chip

2005-2010

Box1975-90

TodayToday

CardIntegrated2000-2005

2.5 cm

* T. Pany: Navigation Signal Processing for GNSS Software Receivers, Artech House, 2010


SOFTWARE RECEIVER APPLICATIONS

Application Justification

GPS/INS integration Easy access to tracking loops and convenient development environment

GPS reflectometry Detailed signal analysis in post processing, with arbitrary number of correlators

Indoor reference receiver

Combine indoor and outdoor signals at signal processing level yielding an accurate determination of signal attenuation

Phased array antennas Simple data flow inside the receiver of the different antennas and easy access to signals

GPS translator system Flexible receiver at server side. RF frontend as part of weapon which is finally destroyed is cheaper than complete receiver

Network based positioning of mobile phones for E911

Flexible receiver at server side

Signal analysis tool Possibility to implement dedicated analysis and monitoring algorithms with visualization capabilities

High-end receiver Possibility to implement high-end signal processing and navigation algorithms such as frequency domain signal processing, multi-correlator, vector delay lock loop etc.

* T. Pany: Navigation Signal Processing for GNSS Software Receivers, Artech House, 2010


MOORE’S LAW

* Gordon Moore


ENTERING A NEW WORLD GRAPHENE: SILICON’S SUCCESSOR?

* www.amo.de

•

Graphene is a one-atom thick sheet of carbon atoms arranged in hexagonal rings

•

Enormous potential for serving as an excellent electronic material

•

New kinds of transistors based on quantum physics

–

The electrons find no obstacles in graphene

–

The electrons roam freely across the sheet of carbon, conducting electric charge with extremely low resistance


THE FUTURE IS THE INTEGRATION OF ELECTRONICS AND PHOTONICS

* www.amo.de


OVERVIEW

•


•


•

Clocks

•

Receivers

•


•

Conclusions


INTERFERENCE SOURCES

•

Unintentional –

Received power levels only –160dBW into 0dBIc antenna▫

Easy to disrupt operation▫

Shared use of ARNS band

–

Harmonics from radio sources – examples:▫

Digital television▫

Regulatory requirements insufficient to provide protection

▫

Ultra-wide band transmissions▫

Multiple sources could engender widespread interference

–

Out of band emissions from adjacent bands–

MSS emissions into L1 band

•

Intentional–

Jamming used to deny access to navigation signals–

Inter and intra-system noise


EFFECTS OF INTERFERENCE

•

Degradation of signal to noise ratio

Increase in noise level due to interference source

Lowering effective signal level

Blocking of signal in receiver’s RF and IF stages via RF filtering or signal blanking

Reduction of signal content

Noise interference

Continuous Wave (CW) interference

•

Analysis technique

Computation of

Effective C/N0

as absolute figure of merit

Degradation of C/N0

as relative figure of merit


MANAGING GNSS INTERFERENCE

•

There is a substantial amount of information on interference that must be verified, analyzed, and coordinated

•

GNSS Service Disruptions

Detection / Reporting

Information & Data Analysis

Identification / Location

Mitigation

Reference: 2Reference: 2ndnd

GNSS Vulnerabilities and Solutions Conference, GNSS Vulnerabilities and Solutions Conference, BaskaBaska, , KrkKrk

Island, Croatia, Sept. 3, 2009, Hank Island, Croatia, Sept. 3, 2009, Hank SkalskiSkalski, U.S. Dept. of Transportation, U.S. Dept. of Transportation

US Approach


ESA ACTIVITIES ON RFI DETECTION AND LOCATION

Phase A RFI Mission Study and Definition of a Payload

RFI detection, characterization, reporting and information to the GNSS users


OVERVIEW

•


•


•

Clocks

•

Receivers

•


•

Conclusions


CONCLUSIONS

•

After 2020: More than 40 MEO navigation satellites in view

Higher accuracy and availability (urban areas), redundancy allows more sophisticated methods (robustness, advanced RAIM algorithms, etc.)

If signals RF compatible and

interoperable

However, further congestion of L-band increases noise floor

New frequency bands for evolution ?

C-band, S-band, other bands ?

•

Integrity: Global versus Regional Systems versus User Level

Multi-frequency/system regional SBAS can cover almost whole world and ARAIM may serve aviation

Just sophisticated RAIM for non-aviation integrity?


•

Improvements in payloads

Higher flexibility and power, on-board integrity monitoring

•

Rebalance of complexity between space and ground segment

ISL allow reduction in ground stations

Integrity moves to user level•

New space and ground clocks in development

Mini PHM, optically pumped Caesium, laser-pumped RAFs, cold atoms/trapped ions, clock ensemble in space, optical clocks

Higher accuracy (relativistic positioning needs 10-19)

However, satellite navigation needs primarily stable space clocks!

•

Geo-based Time Reference System in Space

Distribution of time from GEO to MEO may allow cheaper/simpler clocks on MEO

CONCLUSIONS


•

Future receiver development

Assisted GNSS

Real S/W receivers versus FPGA

Chips

Silicon > Graphene

Electronics and photonics merge in future

Radio Frequency spectrum is full

Intentional versus unintentional interference

Degradation of navigation performance

Security aspects for protected signals

Spectral overlap

CONCLUSIONS


Measure what is measurable,

and make measurablewhat is not so.

Galileo Galilei*1564 1642

13

Documents

QUO VADIS? Where are we going in Satellite Navigation?web.stanford.edu/group/scpnt/pnt/PNT10/presentation_slides/3-PNT...QUO VADIS? Where are We Going in Satellite Navigation? Guenter