Difference between revisions of "Global navigation satellite system (GNSS)"

From FIThydrowiki
Jump to navigation Jump to search
Line 106: Line 106:
  
 
=Application=
 
=Application=
−
The 1D model of BASEMENT is based on river cross sections and its main application are river reaches where the level of detail is less important. The 2D model uses a triangular computational grid to reproduce the topography and can be applied to more detailed and complex problems than the 1D model, e.g. the inundation or river bar formation. BASEMENT supports Windows as well as Linux platforms and includes a graphical user interface (GUI) which supports the user during the model setup and simulation process (Figure 2). For grid generation, the QGIS plugin BASEmesh is provided by the developers and for visualization of the results, among others, the QGIS plugin Crayfish (QGIS 2.8) from Lutra Consulting (https://www.lutraconsulting.co.uk) can be used (Figure 3).
+
GNSS systems are used to georeferenced measurements. It is usually used in connection with other systems, such as ADCP, Drones, devices for monitoring fish migration, and other devices where the exact location is important.  
 +
 
 +
It is important to be aware of the accuracy of the GNSS data and if it fits the measurement. For bathymetry measurements it is recommended to have accuracy within a few cm, while discharge measurements can be done with accuracy at the submeter level.
 +
 
 +
There are mainly three different types of GNSS accuracy:
 +
#Standard, such as in cell phones and car navigation. The accuracy lies within 3-5 m horizontally and 5-20 m vertically. These systems don’t receive any correction signal.  
 +
#Advanced receivers, usually referred to as “differential GPS”. These are used in most scientific instruments. The accuracy lies below 1 m horizontally and 2 m vertically.
 +
#RTK-GPS need an internet connection to receive a correction signal. This usually is a real time signal (RTK = Real Time Kinematic), but it is also possible to get the correction for post processing.
  
 
=Other information=
 
=Other information=

Revision as of 14:29, 24 June 2019

Note: I (Bendik) have copy-pasted this as it was from the report. I don't think it is very good or that it necessarily belongs here. Review/revise.

Quick summary

Figure 1: Combination of 1D and 2D models in BASEMENT (source: VAW).
Figure 2: Graphical user interface of BASEMENT (source: VAW) (click to enlarge).
Figure 3: Visualization of BASEMENT results with QGIS plugin Crayfish (source: VAW) (click to enlarge).

Developed by: USA, EU, China, Russia

Date:

Type: Method

Suitable for the following [[::Category:Measures|measures]]:

Introduction

GPS is often used as a synonym for all of the different systems (Table 1).

Table 1: Different systems called as GPS.

System

BeiDou

Galileo

GLONASS

GPS

Owner

China

European Union

Russia

United States

Coverage

Regional, global by 2020

Global by 2020

Global

Global

Status

Basic service by 2018, to be complete by H1 2020

Operating since 2016, 2020 completion

Operational

Operational

Precision

10 (public) 0.1m (encrypted)

1m (public) 0.01m (encrypted)

4.5m - 7.4m

15m (no DGPS or WAAS)

Application

GNSS systems are used to georeferenced measurements. It is usually used in connection with other systems, such as ADCP, Drones, devices for monitoring fish migration, and other devices where the exact location is important.

It is important to be aware of the accuracy of the GNSS data and if it fits the measurement. For bathymetry measurements it is recommended to have accuracy within a few cm, while discharge measurements can be done with accuracy at the submeter level.

There are mainly three different types of GNSS accuracy:

  1. Standard, such as in cell phones and car navigation. The accuracy lies within 3-5 m horizontally and 5-20 m vertically. These systems don’t receive any correction signal.
  2. Advanced receivers, usually referred to as “differential GPS”. These are used in most scientific instruments. The accuracy lies below 1 m horizontally and 2 m vertically.
  3. RTK-GPS need an internet connection to receive a correction signal. This usually is a real time signal (RTK = Real Time Kinematic), but it is also possible to get the correction for post processing.

Other information

In addition to the use on regular Windows and Linux workstations, the upcoming version 3.0 of BASEMENT (March 2019) is designed to run on graphical processing units (GPUs) and distributed memory computer clusters allowing engineers to tackle problems with very large computational domains or long simulation time.

Relevant literature

  • Vetsch D., Siviglia A., Caponi F., Ehrbar D., Gerke E., Kammerer S., Koch A., Peter S., Vanzo D., Vonwiller L., Facchini M., Gerber M., Volz C., Farshi D., Mueller R., Rousselot P., Veprek R., Faeh R. 2018. System Manuals of BASEMENT, Version 2.8. Laboratory of Hydraulics, Glaciology and Hydrology (VAW). ETH Zurich. Available from http://www.basement.ethz.ch.

Contact information

Website (download, tutorials, etc.): http://www.basement.ethz.ch

Email: basement@ethz.ch

Retrieved from "https://www.fithydro.wiki/index.php?title=Global_navigation_satellite_system_(GNSS)&oldid=2047"