?????????????????????????????????????Global Positioning System: GPS

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?????????????????????????????????????Global
Positioning System GPS

• ????? ????????????????????????? ??????????????
  ????????????????????chaya_at_chiangmai.ac.th

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???????
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Global Positioning System GPS
GPS ??????????????????????????????????????????????
????????????????????????????????????????
GPS ?????????????????????????????
??????????????????????? ?

• ?????????? Line of Sight
• Any time of day and night/ All weather
• Very high geodetic accuracy
• ??????????????????????????????????????????????

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????????????????????? GPS
????????? (Space Segment)
????????????? (User Segment)
?????????? (Control Segment)
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????????????????????? GPS????????? (Space
Segment)

• ???????? 24 ??? ?? 6 ??????
• ????????????????????????????? 4 ???
• ???????????????? 55 ?????????????
• ??????????????????????? 22,200
  ?????????????????????
• ????????????????????? 12 ???????
• ???????????????????????????????????????????
• ?????????????????????????????????????????? L1???
  L2

Name NAVSTAR Manufacturer Rockwell
International Altitude 10,900 nautical
miles Weight 1,900 lbs (in orbit) Size 17 ft
with solar panels extended Orbital Period 12
hours Planned Lifespan 7.5 years Constellation
24 satellites
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????????????????????? GPS?????????? (Control
Segment)

• Calibrates and Synchronize ????????
• ?????????????????????????????????
• ???????????????????????????????????????????????
• ??????????????????????????

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????????????????????? GPS????????????? (User
Segment)

• ??? RF ??????????????????????????????????????????
  ??????????????????????????????????????????
  ???????????????????????
• ??? Baseband ?????????????????????????????????????
  RF ??????????????????????? ??????????????????????
  ???????
• ???? Microprocessor ?????????????????????
  Baseband ???????????????????????????
  ????????????????????????? ???? ??????????? ???????

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How GPS Work?
4. Once you know distanceto a satellite, you
then needto know where the satelliteis in space
5. As the GPS signal travelsthrough the
ionosphere and the earths atmosphere, it gets
delayed
3. To measure travel time,GPS needs very
accurateclocks
1. Triangulation from satellitesis the basis of
the system.
2. To triangulate, GPS measures distance using
the travel timeof a radio message
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??????????????????????????? GPS
????????????????
???????? 1
???????? 2
???
???????? 3
???????????????????????????????????????? GPS
??????????????????????????????????????? 3
???????????????????????????????????????
???????GPS?????????????????????????????3??????????
??????????????????? ????????????????????????? GPS
???????????????????????????? ???????? X ????
??????? ??????????????? 3 ????????????????????????
?????????????? GPS ??????????????
(186,000?????????????)????????????????????????????
???????????????? ???????????????????
??????????????????????????
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??????????????????????????? GPS
?????????????????????????????????????????????????
GPS ??? 0.10 ?????? ????????????????????????? GPS
??? 18,600 ???? (186,000 ????????????? X 0.10
?????? 18,600 ????) ????????????????????????????
?????????????????????????????????? 18,600 ????
??????????????????????????????????????????????????
??????????????????
??????????????????????????????????????????????????
?? GPS ??? 0.08 ?????? ?????????????????????????
GPS ??? 13,200 ???? (186,000 ????????????? X 0.08
?????? 13,200 ????) ????????????????????????????
?????????????????????? Intersect
?????????????????????????????????????????????? 2
????????????????
???????? 1
???????? 2
???
???????? 3
??????????????????????????????????????????????????
?? GPS ??? 0.06 ?????? ?????????????????????????
GPS ??? 11,160 ???? (186,000 ????????????? X 0.06
?????? 11,160 ????) ????????????????????????????
?????????????????????? Intersect
??????????????????????????? 3 ???
?????????????????????????????? 2
????????????????????? 3 ??????????????????????????
????????????????????????????? ?????????? GPS
??????????????????????????????????????????????????
????????????? GPS ??????????? ????????????????????
?????????????????????????????????????????????
?????? ???????????????????????? 3
????????????????????? ??????????????????? GPS
???? ?????????????????????????? (
??????????????????) ??????????????????????????????

http//www2.cs.science.cmu.ac.th/seminar/2547/GPS/
index4.htm
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??????????????????????????? GPS

• ????????????????????????( Standard Positioning
  Service, SPS)????????????????????????????????????
  ??????????????????????????? ??????????????????????
  ???????????????????????????????????????
  ??????????????????????????????? ??? 100 ????
  ???????? 156 ???? ????????? ?????????????????????
  Coordinated Universal Time (UTC) 340 nsec
• ????????????????????????( Precise Positioning
  Service, PPS)????????????????????????????????????
  ??????????????????????????? ??????????????????????
  ??????????????????????????????????????????????????
  ????? ????????????????????????????????????????????
  ????????????????????????????????????????????????
  ?????????????????????????????????? 22 ????
  ???????? ??? 27.7 ???? ?????????
  ????????????????????? UTC 200 nsec

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GPS Accuracy

• ????????????????????????(Satellite and Receiver
  Clock Errors)
• ????????????????????????????????Dilution of
  Precision (DOP)
• ?????????????????????????? Selective
  Availability (S/A)
• ??????????????????????????????(Ionospheric and
  atmospheric delays)
• ????????????????????????????(Multipath Error)

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Differential GPS the ultimate in accuracy
Reference receivers
Field receivers
Error correctionmessage
Field receivers
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GPS Fieldwork
???????? ???? ??????? ??????????????????????
???????????????????????????????
???????????????????????????? GPS
?????????????????????????
????????????? ??????????????????????????
??????????????????????? Base Station
????????????????
???????? ????????????????
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Global Navigation Satellite Systems (GNSS)
Global Navigation Satellite Systems (GNSS) is the
standard generic term for satellite navigation
systems that provide autonomous geo-spatial
positioning with global coverage.

• GLONASSThe formerly Soviet, and now Russian,
  Global'naya Navigatsionnaya Sputnikovaya Sistema
  (Global Navigation Satellite System), or GLONASS,
  was a fully functional navigation constellation
  but since the collapse of the Soviet Union has
  fallen into disrepair, leading to gaps in
  coverage and only partial availability. The
  Russian Federation has pledged to restore it to
  full global availability by 2010 with the help of
  India, who is participating in the restoration
  project
• GalileoThe European Union and European Space
  Agency agreed on March 2002 to introduce their
  own alternative to GPS, called the Galileo
  positioning system. At a cost of about GBP 2.4
  billion,4 the system is scheduled to be working
  from 2012. The first experimental satellite was
  launched on 28 December 2005. Galileo is expected
  to be compatible with the modernized GPS system.
  The receivers will be able to combine the signals
  from both Galileo and GPS satellites to greatly
  increase the accuracy.
• CompassChina has indicated they intend to expand
  their regional navigation system, called Beidou
  or Big Dipper, into a global navigation system a
  program that has been called Compass in China's
  official news agency Xinhua. The Compass system
  is proposed to utilize 30 medium Earth orbit
  satellites and five geostationary satellites.
  Having announced they are willing to cooperate
  with other countries in Compass's creation, it is
  unclear how this proposed program impacts China's
  commitment to the international Galileo position
  system.

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Global Navigation Satellite Systems (GNSS)
Comparison of GNSS systems
System Country Coding Orbital height period Number of satellites Status
GPS United States CDMA 22,200km, 12.0h 24 operational
GLONASS Russia FDMA 19,100km, 11.3h 20 operational with restrictions, CDMA in preparation
Galileo Europe CDMA 23,222km, 14.1h 27 in preparation
Compass China CDMA 21,150km, 12.6h gt30 in preparation

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????????????????? GPS

• ???????????
• ????????????????????????????
• ???????????????????

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????????????????? GPS
AVLS (Automated Vehicle Location System)
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????????????????? GPS

• ???????????????????? GPS
• ????????????????
• ???????????????????????
• ????????????????????????

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????????????????? GPS

• ??????????????????????????
• ???????????????????
• ????????????????????????
• ???????????????????????????????????????????

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????????????????? GPS

• ????????????????????????
• ???????????????????????????
• ???????????????????????????????????????

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????????????????? GPS
?????????????? (Logistics) ??????????????????

• - ???????????????????
• ?????????????
• ??????????? ?????????????

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?????? Function Go To ?? GPS
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?????? Function Go To ?? GPS

• ?? MARK 1 ?????

• ?????????????????????????

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?????? Function Go To ?? GPS

• ?????????????????????????????????????????????????
  ?
• ???????????????? OK

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?????? Function Go To ?? GPS

• ????????? waypoints
• ??????????? ????????????????????????

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?????? Function Go To ?? GPS

• ???????????????????? Go To ???????????????????????
  ????????????????????????????????????????

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?????? Function Tracking ?? GPS

• ????????? Tracks ???????????? PAGE
• ????? Track ????????????? ?? ?????????????
  ????????? Clear

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?????? Function Tracking ?? GPS

• ?????????????????????? ??????????????????? Track

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?????? Function Tracking ?? GPS

• ???????????????????????????????????????????
  ??????????????????????? ?????? ??????? SAVE
  ??????????????????????????????????????????