GPS and Survey Flashcards
GPS
Global Positioning System
In Situ Data
are collected on the ground by a human being/special data collection instruments.
Important characteristic of in situ datasets
You identify where each measurement was collected in geographic space.
GNSS
Global Navigation Satellite Systems
Important Applications of GPs (5)
- determining your exact location anywhere on the surface of the Earth
- Having the GIS network software identify the optimum route to a desired location.
- the use of GPS onboard an aircraft in support of the collection of digital aerial photography, LiDAR, or other types of remote sensor data.
- The GPS determines the x, y, and z position of the aircraft at the exact instant that an aerial photograph is taken or a LiDAR pulse of laser energy is emitted or received.
- information from airborne GPS receivers is used on commercial aircraft to constantly transmit the plane’s position to air-traffic controllers and to help the pilot land the plane
FIVE examples of modern uses for GPS
- crowd sourcing
- Precision agriculture
- collecting GPS points
- accurate terrestrial land surveying
- using GPS and GIS to find the optimum route to a location
How many satellites are necessary to provide full GPS coverage of the Earth?
24
4 placed in 6 orbits, 60° apart
Three segments of a GPS
SPACE segment
CONTROL segment
USER segment
Space Segment
24 satellites orbiting the earth, with 4 place in 6 orbits, 60°apart.
Control Segment
Control to launch, maintain and constantly determine location of satellites.
- atomic clock
User segment
People on the ground us GPS receivers to communicate with the GPS satellites to obtain continuous, accurate, worldwide, all-weather x,y,z position.
Crowd sourcing
the act of outsourcing tasks traditionally performed by an employee or contracter, to an undefined, large group of people or community
GPS and precision agriculture
GPS helps to control special tractors and farm implements during land preparation, planting, fetilization and harvesting
why might you collect GPS points
To document the exact location of the route you have taken/compute the speed that you travelled the route
GPS receivers are composed of:
AN ANTENNA
CENTRAL PROCESSING UNITY
ATOMIC CLOCK