GNSS Flashcards
1
Q
What are the elements of the GPS system?
A
Space segment
Control segment
User segment
2
Q
What are the properties of the space segment of GPS?
A
- Orbits at 20,200km
- At least 24 satellites
- 6 Orbital planes
- 12 hours to complete one orbit
- Each orbital plane is at 55˚ to the equator
3
Q
What is contained on the navigation message obtained form the GPS satellites? What is each?
A
- Ephemeris: present position of the satellite in orbit
- GPS time reference: Atomic clock time of the satellite
- Clock corrections: Self explanatory
- Almanac data: parameters for the orbital data of the entire constellation
- System maintenance status: Self explanatory
4
Q
What is RAIM?
A
Receiver autonomous integrity monitoring
Receiver will monitor the integrity of the position solution,, and the number of reliable satellites data is being taken from
5
Q
What are the modes of GPS receiver operation?
A
Navigation with RAIM
2D or 3D navigation without RAIM
Dead reckoning
6
Q
What are the errors of the GPS?
A
- Ephemeris error
- Multi-path error
- Ionospheric propagation effects
- Tropospheric propagation effects
- Receiver error
- Clock error
- Interference
7
Q
What human factor considerations/ errors are there when using the GPS?
A
- Mode Error
- Data entry error
- Cross checking
- Automation induced complacency
- Non standard displays
- Control knobs and switch designs
- Compulsive fiddling
- Loss of situational awareness
