Leadership inLocation Technology

Location Anywhere, AnytimeGreg Turetzky for Stanford EE380

4/19/06

2

Is Location Important?Is Location Important?

3

Huge Growth in Mass Market Devices

AutomotiveAutomotive Mobile PhoneMobile Phone

ConsumerConsumer Mobile ComputeMobile Compute

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From “Where am I?” to “Where are you?”

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Future Products (?)

make sure you will never be forgottenforget-me-not panties™ have built-in GPS and unique sensor technology giving you the forget-me-not advantage.

protect her privatesEver worry about your wife cheating?

Want to know where your daughter is late at night?

Need to know when your girlfriend's temperature is rising?

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Early Satellite Navigation

• TRANSIT Doppler– (aka Navsat)

• 1960 -1996• Polar Orbits

– 1100 Km– 106 minutes

• 5 to 10 Satellites– Observe multiple

measurements off of 1 Satellite

Primarily used by Polaris submarines to reset their inertial guidance systems.

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A Short History of GPS

1973 Defense Navigation Satellite System (DNSS) passes Defense Systems Acquisition Review Council (DSARC)

1978 (Feb 22) PRN #1 Successfully Launched

1970

2000

1980

1990

1982 GLONASS #1 Launched

1990 Selective Availability Activated

1994 GPS Declared fully active

•1994 – FAA awards contract for Wide Area Augmentation System (WAAS) 1995 – SiRF Started

1986 – Motorola 4 Channel Eagle ($19K, 22 W)Q

2004 SiRF surpasses 10MU

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GPS - SPACE SEGMENT

• 24 satellites + 3 active spares• 6 orbital planes at 55°, 12 hour orbits, 20,000 km

nominal altitude

• Free worldwide coverage • Continuous signal - all weather

• L1 = 1575.42 MHz, L2=1227.6 MHz• PRN C/A (L1) and P (L1 & L2)

• Continuous navigation message (satellite ephemeris and almanac data)

• Measurement Data – Pseudo-range (distance to the Sv)– Carrier phase (wavelengths )

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GPS Satellite

GPS Antenna right-hand Circular Polarized (60W)

“Event”Detector

Uplink Antenna

Power CellsPositioning Thrusters

Q

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GPS Block IIR-M

• Second Civilian Signal– More Accuracy– 1.1m

• 1st Launch 2005• On line in 2010

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GPS Signals: Present and Future

L5ARNS/RNSS Band

L1ARNS/RNSS Band

L2RNSS Band

P(Y)

C/A

L2CM

L5

L1C

Current GPSDual Frequency w/

Semi-codeless P(Y)

Block IIR-MLaunch 2005Dual Frequency L1 C/A & L2C

Block IIFLaunch 2007Three Frequency L1 C/A, L2C, & L5

Block IIILaunch 2013

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

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GPS at L1

-95

-90

-85

-80

-75

-70

-65

-60

-55

-20 -15 -10 -5 0 5 10 15 20

Offset from 1575.42 MHz Center Frequency (MHz)

Pow

er S

pect

ral D

ensi

ty

(dB

W/H

z) R

elat

ive

to 1

Wat

t L1 C/A

L1 P(Y)

L1 M

L1C

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WAAS - Integrity & Accuracy

Roughly 4x per year a GPS SV Goes “Unhealthy”–WASS: 6 second alert for unhealthy SV–GPS: 30 minute alert for unhealthy SV via GPS system

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Signal Attenuation - How much?

• Forests: Large range (foliage type, humidity, trunks)• Residential houses - up to 30 dB• Commercial buildings: variable, in excess of 40 dB• Non-homogeneous attenuation exacerbate multipath

Transmitter

Reflected signal

ŅAttenuateddirect signalÓ

UserAbsorbed signal

Correct Range

Path of least resistance

Courtesy of Prof. LaChapelle at U of Calgary

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If the signal is too small to see in 1 msec, we must narrow the receive bandwidth. Coherent integration is the first choice technique.

#5 High Sensitivity GPS

Adapted from Darius Plausinaitis, Aalborg Univ. dpl@gps.aau.dk

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A-GPS: more useful, more often

Assisted GPS – Ephemeris, Differential Corrections, Time, and Frequency

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Galileo System

• Global Navigation Satellite System built by European Union – Operational 2008– The first Galileo test satellite – GIOVE-A was

launched on Dec.28, 2005– First navigation signals were transmitted by

GIOVE-A on Jan.12, 2006• Interoperable with GPS• 30 satellites in three Medium Earth Orbit MEO

planes at 23,616km above the earth– 9 satellite + 1 spare per plane– The inclination of the orbits was chosen to ensure

good coverage of polar latitudes, which are poorly served by the US GPS system

• One revolution 14 hours 4 min

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GNSS Spectrum

L5

E5 E6 L1E2 E1

1164

MHz

1214

MHz

1260

MHz

1300

MHz

1559

MHz

1587

MHz

1591

MHz

1563

MHz

1215

MHz

1237

MHz

L2

RNSS Bands RNSS Bands

ARNS Bands ARNS Bands

1610

MHz

GALILEO Bands (Navigation)

GPS Bands (Current & modernized)

GLONASS Bands (Current & modernized)

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GPS & Galileo at L1

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Data Collection (SiRF and Stanford)

BOC(1,1)BOC(15,2.5)

• Dish allowed us to see Galileo GIOVE-A signal when transmission was initialized• Code not necessary for data capture• Vector Signal Analyzer used to capture data from transmission

GIOVE-A E1-L1-E2

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Galileo First Contact

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GLONASS – Russia

• Soviet Era System• 2001 – 6 SVs• 2005 – 13 SVs• 18 SVs by 2008• 3 year life – today • 7 year life – new• Funding from India

Glonass Receivers use Multiple Frequencies = $$$

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QZSS – Japan

• Quasi Zenith Satellite System

• Modification of Geosynchronous Orbit

• Covers Japan and Southern Asia

• WAAS like data on L1, L2 and L5

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Satellites alone are never enough

Plus parking garages, tunnels, subway systems, etc.

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SiRF InstantFIX™System Model Overview

SiRF GPS Monitoring Information

SiRF Server SGEE

Ephemeris Synthesis

'UTTf xyzr

XYZxyzNS ∇⋅⋅= φλ

λφ λφφuU

ruU

ru

rUU r ⋅

∂∂

⋅⋅

+⋅∂∂

⋅+⋅∂∂

=∇'

cos1'1''

[ ]∑ ∑

∑

∞

= =

∞

=

⋅+⋅⋅

⋅+

⋅⋅

⋅−=

1 1

*

01

*

sincos)(sin

)(sin'

l

l

mlmlmlm

l

e

ll

l

l

e

mSmCPra

r

JPra

rU

λλφµ

φµ

∫ ⋅⋅⋅

⋅

=M

ll

le

l dmPRaM

J )'(sin1* φ

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TTFF Comparison

0102030405060708090

100

TTFF

Sec

onds

Open Sky UrbanCanyon on

Roof

UrbanCanyon on

Dash

InstantFixAutonomous

SF Urban Canyon

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1 Day Old Synthetic Ephemeris

Typical San Francisco Run with Extended Ephemeris

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7 Day Old Synthetic Ephemeris

Typical San Francisco Run with Extended Ephemeris

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External Sensors

• Inertial Navigation has been around for a long time– Accelerometers, Gyros, Compasses– Really big and really expensive

• Technology advances such as MEMS are moving fast– But MEMS does not follow Moore’s law

• Size and price barrier has been overcome today– Airbag, HDD protection, screen orientation, jitter control, stability

control are consumer products today

• Level of accuracy is the main barrier– Measuring acceleration or heading for their own sake is easy– Integrating those measurements for navigation requires an

exponential increase in performance

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Automotive leading the way

• The car platform has several major advantages– Not 6 degrees of freedom, only 2– Otherwise, the wheels don’t do much good

• Many sensors already built in– Odometer is good for distance– Gyro can be hard mounted to body frame

• Automotive technology is slow, consumers are fast– Need portable solutions with no mounting restrictions

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Anywhere, anytime today in a car

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Next Challenge

• Body frame– Belt clip provides good potential– Limited dynamics, wireless connection, pedometer

optimization

• Hand frame– Really want it inside your cell phone– More dynamics, no pedometer

• Object frame– Any item