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

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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.  
 
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=
 
=Quick summary=
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[[file:basement_1d_2d.png|thumb|250px|Figure 1: Combination of 1D and 2D models in BASEMENT (source: VAW).]]
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[[file:gps_boat_remote.png|thumb|250px|Figure 1: Differential GPS mounted on a remote-controlled boat for bathymetry and discharge measurements.]]
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[[file:basement_gui.png|thumb|250px|Figure 2: Graphical user interface of BASEMENT (source: VAW) (click to enlarge).]]
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[[file:gps_single_point.png|thumb|250px|Figure 2: RTK-GPS for single point measurements at very high accuracy (< 1 cm).]]
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[[file:basemet_qgis.png|thumb|250px|Figure 3: Visualization of BASEMENT results with QGIS plugin Crayfish (source: VAW) (click to enlarge).]]
 
  
 
Developed by: USA, EU, China, Russia
 
Developed by: USA, EU, China, Russia

Revision as of 14:32, 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: Differential GPS mounted on a remote-controlled boat for bathymetry and discharge measurements.
Figure 2: RTK-GPS for single point measurements at very high accuracy (< 1 cm).

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

General accuracy is depending on

  • Number of satellites / selective availability
  • Angle between the satellites = Dilution of Precision (DOP)
  • Reflection from buildings/obstacles = multipath error
  • Atmospheric conditions

Only the last point, the atmospheric conditions, can be corrected with the differential and RTK GPS.

Relevant literature

Contact information

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

Email: basement@ethz.ch

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