Contents of this page may be automatically translated, we take no responsibility for the accuracy of the translation. Feel free to contact our customer support centre if you have any questions.
Network RTK is a real-time service for users using GNSS/RTK equipment. You also have access to a few support services based on your needs for planning and quality assurance.
Use our services
Description of the service
Network RTK provides the possibility of position determination in the reference system SWEREF 99 with measurement uncertainty at the centimetre level. The service also includes Network DGNSS, with the possibility of position determination with measurement uncertainty at meter level.
The service currently provides correction data for the satellite systems GPS, Glonass, Galileo and Beidou.
Network RTK requires a connection, usually via mobile Internet. An M2M SIM card (SIM card for machine-to-machine communication) is included free of charge in the subscription to Network RTK, for those who wish. Read more about the different kinds of subscriptions for Network RTK.
If you do not have the possibility to measure with Network RTK, you can use Virtual rinex for post-processing of your measurements.
Expected positional uncertainty
The positional uncertainty you can expect when using Network RTK depends primarily on the uncertainty in the path of the GNSS signal, the uncertainty in the correction data from the service, and the uncertainty in your own measurement procedure.
Measurement uncertainty is a measure of how large the spread of measured values is, e.g. for a number of network RTK measurements. Read more about the concept of measurement uncertainty (new window).
When measuring with Network RTK, and you have good measurement conditions the possibility, it is possible to obtain a measurement uncertainty, in the reference system SWEREF 99, according to the table below: The measurements are estimated on the basis of test measurements of the network RTK service and specified with coverage factor 2, which means that they are expected to cover at least 95% of all measurement values.
| In an area with about 10 km distance between the Swepos- stations |
In an area with about 35 km distance between the Swepos- stations |
In an area with about 70 km distance between the Swepos- stations |
|
|---|---|---|---|
| Determination of horizontal position (2D) | 10-15 mm | 15-20 mm | 25-40 mm |
| Determination of vertical position (above the ellipsoid) |
15-20 mm | 30-40 mm | 45-60 mm |
The values only include measurement uncertainty in the GNSS measurement; thus, the geoid model's uncertainty for height measurement must be added to abtain the uncertainty of the RH 2000 height determination.
The estimation of measurement uncertainty also presupposes that the various sources of error that affect the GNSS signal's path from satellite to receiver are at a "normal" level; see more in HMK – GNSS-based detail measurement. With the help of our support services, such as the ionosphere monitor, you have can assess whether the sources of uncertainty contribute more than "normal".
Error sources affecting GNSS measurement
Read more about sources of error affecting GNSS positioning.
Many of the sources of uncertainty can be managed using network RTK technology. But depending on how much and how quickly the sources of uncertainty vary on a given place there is also an uncertainty in how well a network RTK system can calculate correction data, which in turn depends on the distance between the reference stations.
Here you can see where the Swepos stations are located (new window).
Measurement procedure and local environment
Finally, the position uncertainty is affected by your own measurement procedure and the local measurement environment. If e.g. averaging of positions does not take place over a long enough time, the measurement uncertainty is negatively affected. Similarly, obstructions of the satellite signals, poor centering or incorrect antenna handling contribute to higher position uncertainty.
To minimize this type of uncertainty, you should follow the recommendations in the short manual and checklist and HMK – GNSS-based detailed measurement.
Terms and conditions
Questions and answers
Network RTK is a technology for high-accuracy GNSS positioning in real-time. The technology is based on permanent reference stations, e.g. Swepos.
The reference stations continuously observe the same satellites as the user, hence the error sources that currently affect the user's GNSS measurements can be estimated. The so-called correction data is calculated at Swepos' control centre and is sent to the user's GNSS equipment via mobile Internet. The user can then get a position in the reference system SWEREF 99 with an uncertainty at the centimeter level.
Read more about the network RTK technology.
Typical applications for network RTK are
- measurement of objects, i.e. determination of object position
- stake-out, i.e. marking of known positions
- cadastral surveys
- machine guidance and machine control in construction and agriculture applications.
... but all kinds of outdoor applications where you want an accurate position in SWEREF 99 are possible.
- An RTK-type GNSS receiver, i.e. a GNSS equipment performing carrier-wave measurements of several GNSS frequencies. In Sweden, there are vendors of several different RTK brands.
- Free line of sight towards the sky to allow observation of the GNSS satellites. At present, lock of signal is required for at least five GPS satellites.
- Subscription of a network RTK service.
- Mobile Internet access, for connection to the service.
The Swepos staff is available to help with support and troubleshooting. Among other things, we have tools to check your connection to the service. To save time, we suggest that you first go through the checklist for troubleshooting (pdf, in Swedish, new window). The checklist is also available as an appendix to the short manual (pdf, in Swedish, new window).
Some common problems are:
- If you cannot get a so-called absolute position with the RTK receiver - i.e. a position with measurement uncertainty at the meter level without correction data - you will also not be able to initialise a fixed solution using the network RTK service. Make sure you are receiving signals from a sufficient number of GNSS satellites.
- If you use mobile Internet to connect to the service, but do not have mobile coverage where you are, you will not be able to receive correction data from Swepos. Initialisation of a fixed solution then becomes difficult or impossible. Keep in mind that the local mobile coverage varies between different mobile operators.
- Local or temporary disturbances in the atmosphere can make it difficult to initialise a fixed solution and contribute to gross errors (large deviations) in RTK positioning. Using the ionosphere monitor (in Swedish, new window), you can quickly identify any ionosphere-related problems in your region.
We are available to help with support and troubleshooting. Among other things, there are tools for checking your connection to the service.
To save time, we suggest that you go through the checklist for troubleshooting (pdf, in Swedish, new window) before contacting Swepos Control Centre.
If you use mobile Internet to connect to the service, but do not have mobile network coverage where you are, you will not be able to receive correction data from Swepos. The local mobile network coverage varies between different mobile operators, so switching to another operator might provide better coverage.
An alternative to the real-time service can be to post-process your RTK measurements using virtual rinex.