BeginnerTopic 22 of 112Civil & Structural
GPS and GNSS surveying
Satellite positioning gives accurate coordinates.
In depth
GNSS (GPS, GLONASS, Galileo, BeiDou) positions receivers by trilateration to satellites. RTK and PPP give centimetre accuracy using corrections; handheld devices give metres. Needs sky view; multipath and atmospheric errors matter. Widely used for control, mapping and machine guidance.
Key points
- Static vs RTK
- Datum and projection
- Base stations and CORS networks
ExampleConstruction machines use RTK GNSS to cut to design grade.
GNSS gives accurate positions over large areas quickly, so it is used for mapping, machine guidance and monitoring of movements.
What is GPS and GNSS surveying?
Satellite positioning gives accurate coordinates.
Why is it important to understand GPS and GNSS surveying?
GNSS gives accurate positions over large areas quickly, so it is used for mapping, machine guidance and monitoring of movements.
How accurate is GNSS?
Standard handheld receivers give metre-level accuracy, while survey-grade systems with corrections reach centimetre accuracy.
Why can GNSS fail?
Buildings, trees and tunnels block satellite signals, so the signal can be lost or degraded in urban and forested areas.
How is GPS and GNSS surveying used in practice?
Typical applications include guiding a bulldozer blade with satellite positioning on a road job, mapping a large catchment area for a drainage study and monitoring the slow movement of a landslide with GNSS receivers.
What should I learn before GPS and GNSS surveying?
Study "Theodolite and total station" first (topic 21 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of GPS and GNSS surveying?
Static vs RTK. Datum and projection. Base stations and CORS networks.
Can you give an example of GPS and GNSS surveying?
Construction machines use RTK GNSS to cut to design grade.
What comes after GPS and GNSS surveying?
The next topic is "Contours and maps", which builds directly on this one.
How difficult is GPS and GNSS surveying?
It is classed as Beginner in Civil & Structural (topic 22 of 112). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.