Principle, Segment, Limitation, Error of GPS, DGPS, GLONASS, GALILEO
GPS principle
Same as why three or four satellite using. See above answer.
GPS limitation
GPS doesn’t work on some places because of inclination of 55 degree to equator
No control by user
GPS jamming
GPS error
GPS segment
Ground base segment
Space segment
Receiver segment
GPS
27 satellite 24 operation 3 spare
6 orbit
20200 km above
55 degree inclined to equator
Period 11 h 58 m
5-10 m accuracy
DGPS
Where higher accuracy of position fixing required. (survey, drilling, oceanography.)
Used to enhance the accuracy of GPS system.
Not independent, GPS receiver needed
Coverage within 370 km of DGPS reference station
3-5 m accuracy
DGPS principle
DGPS reference station is situated at a fixed location.
From DGPS reference station GPS receiver tracks satellite and make calculation.
GPS receiver also make calculation for it’s actual position.
Finally, correction are sent to GPS user.
DGPS limitation
Not independent, GPS receiver needed.
Coverage within 370 km of DGPS reference station.
For greater coverage more DGPS reference station need to be added.
Lack of integrity
No control by user
GPS error
GLONASS
Russian based satellite system
GPS and Glonass share same principle
GLONASS
27 satellite 24 operation 3 spare
3 Orbit
19100 km above
64.8 degree inclination to equator
Period 11 h 16 m
5.6 m accuracy
GLONASS limitation
Lack of integrity
No control by user
Lack of availability
error
GLONASS error
Satellite clock error
User clock error
Ionospheric and tropospheric delay
Multipath error
Solar flare
Spoofing
GALILEO
European based satellite system
GPS, Glonass, Galileo share same principle
GALILEO
30 satellite 27 operation 3 spare
3 Orbit
23222 km above
56 degree inclination to equator
Period 14 h 05 m
4-15 m accuracy
GALILEO limitation
Lack of integrity
No control by user
Lack of availability
error
GALILEO used for
Search and rescue
Commercial Navigation
