Leadership in Location Technology Location Anywhere, Anytime Greg Turetzky for Stanford EE380 4/19/06
Is Location Important? Is Location Important? 2
Huge Growth in Mass Market Devices Automotive Automotive Mobile Phone Mobile Phone Consumer Mobile Compute Consumer Mobile Compute 3
From “Where am I?” to “Where are you?” 4
Future Products (?) protect her privates Ever 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? make sure you will never be forgotten forget-me-not panties™ have built-in GPS and unique sensor technology giving you the forget-me-not advantage. 5
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. 6
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 1994 GPS Declared fully active 1970 1980 1990 2000 1982 GLONASS #1 Launched 1990 Selective Availability Activated 2004 SiRF surpasses 10MU •1994 – FAA awards contract for Wide 1995 – SiRF Started Area Augmentation System (WAAS) 1986 – Motorola 4 Channel Eagle ($19K, 22 W) Q 7
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 ) 8
GPS Satellite GPS Antenna right-hand Circular Polarized (60W) Uplink Antenna “Event” Detector Power Cells Positioning Thrusters Q 9
GPS Block IIR-M • Second Civilian Signal – More Accuracy – 1.1m • 1 st Launch 2005 • On line in 2010 10
GPS Signals: Present and Future Current GPS C/A Dual Frequency w/ P(Y Semi-codeless ) P(Y) Block IIR-M Launch 2005 L2C Dual Frequency M L1 C/A & L2C Block IIF Launch 2007 L5 Three Frequency L1 C/A, L2C, & L5 Block III L1C Launch 2013 L1C, L2C, L5, & L1 C/A Code L5 L2 L1 ARNS/RNSS Band RNSS Band ARNS/RNSS Band 11
GPS at L1 -55 L1 C/A (dBW/Hz) Relative to 1 Watt -60 Power Spectral Density L1C -65 L1 P(Y) -70 L1 M -75 -80 -85 -90 -95 -20 -15 -10 -5 0 5 10 15 20 Offset from 1575.42 MHz Center Frequency (MHz) 12
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 13
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 e g n a R t c e r r o C Ņ Attenuated direct signalÓ Absorbed signal User Path of least resistance Courtesy of Prof. LaChapelle at U of Calgary 14
#5 High Sensitivity GPS If the signal is too small to see in 1 msec, we must narrow the receive bandwidth. Coherent integration is the first choice technique. Adapted from Darius Plausinaitis, Aalborg Univ. dpl@gps.aau.dk 15
A-GPS: more useful, more often Assisted GPS – Ephemeris, Differential Corrections, Time, and Frequency 16
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 17
GNSS Spectrum GALILEO Bands (Navigation) GLONASS Bands (Current & modernized) GPS Bands (Current & modernized) ARNS Bands ARNS Bands RNSS Bands RNSS Bands E6 E2 L1 E1 E5 L2 L5 1164 MHz 1214 MHz 1215 MHz 1300 MHz 1559 MHz 1563 MHz 1591 MHz 1610 MHz 1237 MHz 1260 MHz 1587 MHz 18
GPS & Galileo at L1 19
Data Collection (SiRF and Stanford) GIOVE-A E1-L1-E2 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 20
Galileo First Contact 21
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 = $$$ 22
QZSS – Japan • Quasi Zenith Satellite System • Modification of Geosynchronous Orbit • Covers Japan and Southern Asia • WAAS like data on L1, L2 and L5 23
Satellites alone are never enough Plus parking garages, tunnels, subway systems, etc. 24
SiRF InstantFIX ™ System Model Overview SiRF Server SGEE SiRF GPS Ephemeris Synthesis Monitoring Information = ⋅ ⋅ ∇ f T XYZ T xyz U ' φλ NS xyz r ∂ ∂ ∂ U ' 1 U ' 1 U ' ∇ = ⋅ + ⋅ ⋅ + ⋅ ⋅ U ' u u u φ λ ∂ r ∂ φ ⋅ φ ∂ λ r r r cos l µ * ∞ a ∑ = − ⋅ ⋅ φ ⋅ U ' e P (sin ) J l 0 l r r = l 1 l µ * ∞ l a [ ] ∑ ∑ + ⋅ ⋅ φ ⋅ λ + ⋅ λ e P (sin ) C cos m S sin m lm lm lm r r l = 1 m = 1 1 ∫ = ⋅ ⋅ φ ⋅ l J R P (sin ' ) dm l ⋅ l * l M a e M 25
TTFF Comparison 100 90 InstantFix 80 Autonomous 70 TTFF Seconds 60 50 40 30 20 10 0 Open Sky Urban Urban Canyon on Canyon on Roof Dash SF Urban Canyon 26
1 Day Old Synthetic Ephemeris Typical San Francisco Run with Extended Ephemeris 27
7 Day Old Synthetic Ephemeris Typical San Francisco Run with Extended Ephemeris 28
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 29
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 30
Anywhere, anytime today in a car 31
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 32
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