GEOGRAPHICAL POSITIONING SYSTEMS GPS

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GEOGRAPHICAL POSITIONING SYSTEMS (GPS)
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GPS

• GPS SATELLITES ( 25)
• GPS RECEIVERS
• WITH COMBINATION, CAN DETERMINE LOCATION ON EARTH
• WAAS
• WIDE AREA AUGMENTATION SYSTEMS (ACCURACY 6 FEET)
• WITH APPROPRIATE RECEIVERS (ACCURACY 1 CM)
• 400MM/YR

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USES

• NAVIGATION
• COMPUTER CONTROLLED
• HARVESTERS
• MINE TRUCKS
• HAND HELD
• HIKING
• ?TURN POINTS
• GLIDERS
• AUTOMOTIVE NAVIGATION
• PDA, CAR COMPUTER

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• SURVEYING
• GPS FOR VISUALLY IMPAIRED
• GEOCACHING
• GAMES
• AIR FLIGHTS
• GPS TO TRACK
• SOME WONT ALLOW TRACKING
• OTHERS ENCOURAGE IT
• PRECISION TIMING
• ATOMIC CLOCKS
• 14 SECONDS DIFFERENCE SINCE 1980
• NO LEAP SECONDS

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TECHNOLOGY

• DOPPLER EFFECT
• (SEE WIKIPEDIA)
• USED TO LOCATE SPUTNIKS
• REVERSE PROCESS TO IDENTIFY LOCATION ON EARTH

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GPS TECHNOLOGY

• 24 SATELLITES 3 SPARE
• 6 ORBITAL PLANES
• 12,600 MILES
• ANY LOCATION ON EARTH 4 SATELLITES IN DIRECT
  LINE OF SIGHT
• TIME SYNCHRONIZED LOCATION CONSTANTLY CONFIRMED

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RECEIVERS

• POSITION
• LATITUDE
• LONGITUDE
• HEIGHT
• SATELLITE SENDS SIGNAL
• BASED ON TIME TO RECEIVE IT, ORBIT IS CALCULATED
• RECEIVER LOCATION CAN BE CALCULATED (COMPLEX)

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IMPROVING ACCURACY
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SELECTIVE AVAILABILITY

• PUBLIC
• MILITARY USE
• DELIBERATE ERROR IN PUBLIC SYSTEMS
• LATER
• SAME ACCURACY IN CIVILIAN SYSTEMS
• SELECTED DENIABILITY IS POSSIBLE

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GPS JAMMING

• INTENTIONAL
• SIZE OF A CIGARETTE BOX
• ATTRACT BOMBS AWAY FROM TARGETS?
• SIMILAR BUT STRONGER SIGNALS
• 50KM INTERFERENCE
• UNINTENTIONAL
• AMPLIFIED TV SIGNALS

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OTHER SYSTEMS

• GLONASS
• LIMITED USEFULNESS
• FULL OPERATION IN 2008
• GALILEO
• TARGET DATE 2010
• CHINA AND FRANCE
• NO DETAILS

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SMART ANTENNAS

• ELECTROMAGNETIC RADIATION IS POLLUTION
• SMART ANTENNAS TRACK LOCATION OF RECEIVER SEND
  SIGNALS DIRECTLY NO BROADCAST

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• MULTIPLE ANTENNAS
• DIGITAL PROCESSOR
• COMBINE AND MANIPULATE INCOMING AND OUTGOING
  SIGNALS
• ANTENNA ARRAYS

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ANTENNAS

• CONVERT ELECTRIC CURRENTS AND VOLTAGES INTO EM
  RADIATION
• BROADCAST IN ALL DIRECTIONS
• DIE OVER DISTANCE
• ABSORBED BY AIR, BUILDINGS ETC
• CAN RECEIVE EM SIGNALS AND CONVERT TO CURRENTS

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RADIO VS. PHONES

• RADIO, TV
• BROADCAST
• CELL PHONES
• NARROWCAST
• RADIO BEAM WILL GO FURTHER IF ENERGY FOCUSED ON
  SENDING IN ONE DIRECTION INSTEAD OF MANY

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• TWO ANTENNAS
• CAN REINFORCE
• HIGHER SIGNAL STRENGTH
• CAN CANCEL EACH OTHER OUT
• LOWER SIGNAL STRENGTH

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ADAPTIVE ARRAYS