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Transcript of GPS
GLOBAL POSITIONING SYSTEM
WHAT IS IT?
The Global Position System (GPS) is a space-based navigation and precise-positioning tool, that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.
HOW IT WORKS?
TYPES OF GPS
What are some of the advantages of using GPS ???
What are some of the disadvantages of using GPS??
Managing Consultant/Snr. GIS Analyst
Geographic Information Solutions (U) Ltd
PARTS OF GPS
COMPONENTS OF A GPS SYSTEM
A GPS receiver calculates its position by precisely timing the signals sent by
GPS satellites high above the Earth. Each satellite continually transmits messages that include
the time the message was transmitted
satellite position at time of message transmission
- 1957 the history begins
-1989 to 1994 launched 1st and 24th satellite
-1996 was officially inaugurated
1.Overview of GPS
History of GPS
Components of GPS
Errors of GPS & how to minimize
2.Introduction to GPS Receiver
5.Hands-on Practice session
This course is meant to give you jump start knowledge on field data collection using GPS receivers
Customizing your Device
GPS Errors and Limitations
This system works pretty well but inaccuracies do pop up- e.gs of errors
Recreational, Mapping and Survey grade GPS devices (<15m, Sub-meter, Sub-centimeter accuracy)
Dependency on signal satellite signal-(obstacles can distort the signal and introduce error)
Benefits of Collecting GPS Data
Ability to link sample data to many attributes
New units of analysis-climatic zones or ethnic regions
New variables can be extracted for multivariate analysis-(involves observation and analysis of more than one statistical outcome variable at a time)
Preparing the GPS receiver for data collection
From the main menu, select
GPS—sets the GPS to Normal,
WAAS/EGNOS (Wide Area
Geostationary Navigation Overlay
Service), or Demo Mode (GPS off).
select Setup >
main menu, select Setup
> Display > Backlight Timeout.
Adjusting the Backlight
press power button to open the backlight status page.
Use the Rocker to adjust the
main menu, select Setup
> Display > Battery Save > On.
Colors—sets the colors used on the
Main, Setup, Find Style—allows
you to select how the main menu,
setup menu, and search menu
—allows you to
take screen captures on the device.
Customizing the Unit
You can customize units of measurements for
distance and speed, elevation, depth,
temperature, and pressure.
1. From the
main menu, select Setup> Units.
2. Select a setting.
3. Select a unit for the setting.
4. Repeat steps 2–3 for each setting
you want to customize.
Important to initialize the GPS receiver before data collection can proceed.
It is done to enable the GPS receiver acquire the latest pseudorandom code, almanac and ephemeris data from the orbiting GPS satellites.
a) it has not been used for long periods of time typically two weeks or more
b) it was been moved through long distances (>500km) since the last time of use.
Hint:- Watch out for GPS Device date and time
"When you fail to prepare your preparing to fail"
Data collection is an expensive venture in terms of time, money and skills involved. E.g area of study is several hundred kilometers away from the base.
Always keep it in mind that in all types of research, data collection is the most critical steps because all subsequent steps e.g. analysis etc.
Minimize costs/loses while maximizing the benefits from it.
• Have a note book for making sketches and taking notes as you work in the field.
• Make sketches of what you map while you work in the field. It helps a lot when compiling the data to make the final product in mapping software.
• Have a good idea of what you are going to map (points, lines or polygon features) and develop a comprehensive coding for each feature type.
• Be sure to carry enough batteries for the GPS to last for the entire duration.
• If necessary create space by freeing the memory of the GPS. It is good practice to download all the data onto the PC before deleting it from the GPS.