35 ways to find your location Chris Heathcote Product experience manager Orange SA

1
35 ways to find your locationChris
HeathcoteProduct experience managerOrange SA

• OReilly Emerging Technology ConferenceFebruary
  9-12, 2004

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why am I here?

• in 10 years' time,
• there will be
• no concept of lost
• There will come an age in the far-off years
  When Ocean shall unloose the bonds of things,
  When the whole broad earth shall be
  revealed Seneca

3
where have we come from?

• the stars, the sun
• reading nature - birds, vegetation, wind
  direction, ocean swells (Polynesians)
• follow a path or coast
• the compass
• the almanac
• the astrolabe
• the sextant
• accurate clocks
• the map
• local knowledge (bushcraft)

4
no magic bullet

• GPS is not the solution
• don't just throw technology at the problem
• appreciate the toolbox
• match needs to methods for you and your users

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measures

• accuracy
• availability
• reliability / trust
• output useful to humans
• output useful to computers
• requirements for conversion (extra enablers
  needed)
• acquire or refine?

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good enough

• what is good enough for your users?
• how much benefit will they get?
• what will it cost them? - time, money,
  frustration
• most current consumer applications - 20-50m

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0. assume The Earth

• EARTH PIC
• accuracy 510 square Megametres
• availability until we conquer space
• requirements belief in a spherical Earth
• best for acquiring

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the time

• (light, dark, timezones)
• mainly relative position of people
• "It's 3 pm here
• "It's 7 am here
• easiest to use when moving long distances
• (these days)
• accuracy 1000 miles (E-W) n/a (N-S)
• availability clocks
• requirements UTC
• best for seafaring, conf calls

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2-7. cultural clues

• which cell phone operators available?
• which wi-fi providers?
• phonebox operators?
• phone number syntax?
• newspapers available?
• language being spoken?
• accuracy 1000 - 100,000 miles
• availability civilisations
• requirements up-to-date list of
  providers/information
• best for acquiring

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8. ask someone

• POLICEMAN PIC
• accuracy 10 metres ........
• availability civilisations
• requirements someone who knows where they are,
  social interaction, a common language
• best for refining

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9. use a map

• maps tell stories
• have to have a map that tells your story
• high cognitive load - getting orientation or
  locating on a map
• accuracy 10 metres - 1 mile
• availability from any good bookstore (good for
  civilisations)
• requirements geolocated mapping
• best for refining

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mobile phone location

• mainly available through network operators
• methods often made invisible to the user and the
  requester
• just different accuracy

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10. cell ID

• network reports which cell you are using
• not always connected to nearest cell
• can appear to move as you roam from cell to cell
• Timing Advance
• http//sitefinder.radio.gov.uk
• accuracy 50 metres - 2 miles
• availability cell coverage
• requirements network hooks
• best for acquiring

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11. cell ID (local lookup)

• extract cell ID from phone radio stack
• can be used for context (home, work)
• cell IDs reported may not correspond to available
  data
• proprietary information needed for real
  geopositioning (or lots of collaborative mapping)
• out-of-date / inaccurate data a problem
• accuracy 50 metres -5 miles
• availability wherever there's coverage
• requirements cell ID to lat/long data
• best for acquiring

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12. angle of arrival (AOA)

• detects angle of phone to transmitter
• network could then use more than one transmitter
  to position
• resolution not always precise
• - can be 45 degrees
• accuracy 50 metres - 200 metres
• availability coverage
• requirements AOA network
• best for acquiring

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13. time difference of arrival (TDOA)

• times signal from handset to cell transmitters
• http//www.trueposition.com
• accuracy 30 metres - 50 metres
• availability wherever there's coverage (and can
  find several transmitters)
• requirements network hooks, TDOA-enabled network
• best for acquiring

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14. observed time difference (OTD)

• phone times differences
• between receiving signals
• phone passes data to
• network for analysis
• accuracy 25 - 250 metres
• availability coverage
• requirements OTD handsets/network
• best for acquiring

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15. assisted GPS

• assistance information produced by cell network
• Simple GPS receiver built into phone handset
• combines with information from one or more GPS
  satellites
• needs AGPS enabled network
• needs more hardware and software in phone
• accuracy 10 metres - 50 metres
• availability wherever there's coverage (and
  clear view of one GPS satellite)
• requirements network hooks, AGPS-enabled
  network, AGPS-enabled phone
• best for acquiring

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geolocation technology
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16. GPS

• pretty good accuracy - at a cost
• Selective Availability
• can appear to move as satellites appear and
  disappear
• other systems - GLONASS, LORAN-C, Galileo

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GPS contd.

• needs more technology (though cost is coming
  down)
• eats battery
• needs clear line of sight to 3 or more satellites
• - cannot be used in a building, let alone in
  your pocket
• slow (for first fix)
• accuracy 10 metres - 75 metres
• availability clear view of three GPS satellites
  - four for elevation
• requirements a GPS receiver (and a few dozen
  satellites)
• best for acquiring

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17. WAAS and other GPS enhancements

• improve accuracy using other satellites, or fixed
  radio stations (EGNOS in Europe)
• reports any foreseen errors in GPS, and corrects
• could be commercialised
• accuracy 2 metres - 25 metres
• availability clear view of three GPS satellites
  other data sources (satellite, radio)
• requirements an enhanced GPS receiver (and a few
  dozen satellites)
• best for acquiring

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18. differential GPS

• two receivers pretty close to each other (200km)
• signals have had same atmospheric errors
• reference receiver is very accurately located
• transmits errors in location to roving receiver
• accuracy 1-3 metres
• availability clear view of three GPS satellites
  at two locations (and communications between)
• requirements DGPS receivers
• best for acquiring

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street furniture
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19. post codes / zipcodes

• lookup list from codes to locations
• can be very accurate for positioning
• proprietary data
• goes out of date
• only available when at a computer/phone book
• accuracy 10 metres to ... miles
• availability not when mobile
• requirements postcode database
• best for acquiring

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20. street names

• not all countries have street names
• hard to enter when mobile (picking is best)
• not unique
• accuracy 20 metres to
• hundreds of miles
• availability pretty good
• requirements street address lookup
• best for acquiring or refining

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20a. street corners / intersections

• high accuracy in built-up areas
• great for motorways
• even provides orientation in US cities (streets
  and avenues)
• accuracy 10 metres to 5-10 miles
  (motorways/"freeways")
• availability pretty good
• requirements street address lookup
• best for refining

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21. street numbers

• great - if they're available
• need street name as well
• accuracy 10-100 metres
• availability pretty good
• requirements street number and address lookup
• best for refining

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22. business names

• databases go out of date
• hard to enter when mobile
• multiple locations
• accuracy 10 metres
• availability good in urban locations
• requirements business address lookup
• best for refining

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23. landmarks and littlemarks

• user picks what they can see
• orientation from large landmarks
• (e.g. skyscrapers)
• maybe from street frontage photos
• accuracy lt 1 mile - as far as the eye can see
• availability ok in urban locations, depends on
• rural geography
• requirements landmark database and lookup
• best for refining

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24-26. phone boxes / public transport stops /
utility markings

• bus stops, fire hydrants,
• street lamps, traffic lights
• proprietary data - but open for
• collaborative mapping
• often localised - to council or area,
• let alone a city
• accuracy 10 metres
• availability ok in urban locations
• requirements access to database
• best for acquisition

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27. location street signs

• dedicated street signs for geolocation
• a nice idea in principle
• installed in London by a taxi firm (proprietary)
• http//www.location-net.co.uk/taxipoint/
• accuracy 10 metres
• availability bad
• requirements installation of street furniture
• best for acquisition

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28. geowarchalking

• postcode
• street name
• street numbers
• lat/long graffiti
• spray paint/sticker barcodes
• accuracy depends
• availability bad
• requirements crazy pirate geo-graffiti gangs
• (Marc Smith's 2)
• best for acquisition

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emerging technology
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29. dead reckoning

• accelerometers, electronic compasses
• highly accurate reckoning of relative position
• needs an accurate location (and time source) to
  start with
• accuracy as good as initial lock
• availability everywhere
• requirements accelerometer and decoding
• best for refining

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30. wi-fi triangulation

• needs wi-fi nodes with a location server
• needs accurate location of nodes
• ubiquitous wi-fi is an American dream
• used in art galleries and museums
• At this conference -
• http//activecampus2.ucsd.edu/oreilly/
• accuracy 5-20m.
• availability bad
• best for refining

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31. broadcast TV/radio triangulation

• needs broadcast reception from three different
  locations
• not likely in many areas (planning regulations)
• accuracy 50m
• availability ok

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32. IP lookup

• currently uninformative (normally the address of
  an ISP or reseller)
• some work to make this more dynamic
• accuracy a country, a continent

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location advertising
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33. encoding of location in access point name /
location points

• wi-fi node advertises location through SSID
• need a standard to be useful in more than one
  network of hotspots
• http//www.orangecone.com/archives/000088.html
• accuracy 100m

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34. local servers / Rendezvous

• fixed machines advertise their location through
  wi-fi
• need a standard
• http//www.headmap.org/
• accuracy 100-300m
• 35. bluetooth
• accuracy 1-100m.

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36. RFID

• RFID card scanned scanner is geolocated
• or in reverse - card senses if scanned (and
  potential lookup)
• http//www.starhill.us/mappingsensornets.html
• accuracy dead - 50m.

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a social future
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37. who you are near (inference)

• people (and people's things) reveal context
• if one of these is geolocated, this could be used
  by all
• 38. objects you are near
• your device asks others around for more-accurate
  locations
• "phone reports 50m accuracy
• "wi-fi connected computer nearby reports 10m
  accuracy by connected GPS
• "bluetooth node reports 5m accuracy with WAAS
• either pick what appears to be the most accurate,
  or aggregate and average the locations

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39. the road most traveled

• recording and aggregation of accurate flows
• time, speed and quantity of movement
• maps autogenerate themselves
• better directions, even see which direction your
  friends have been or normally go
• Amsterdam Real Time, http//www.waag.org

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a few messages

• location finding helps fulfill a basic human need
  - security
• technology helps - but no one technology fulfills
  every need
• what happens when technology fails?
• electronic acquisition pays no attention to
  geography - or the way humans think about their
  location
• choose your weapons carefully
• expect and use more than one method
• what if you want to be lost?

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questions?

• 35ways_at_anti-mega.com
• http//anti-mega.com
• presentation available from
• http//undergroundlondon.com/etech_35ways.ppt
• http//locative.net
• Geowanking mailing list
• geo on irc.oftc.net
• hope you had a good ETCon!
• (thanks to Rael and all at O'Reilly)