While this method provides a fundamental reference with good pass-to-pass accuracy, achieving high absolute accuracy for the rover requires the utilization of an exceptionally precise reference position.
There are three ways of determining the geodetic reference position of your base station:
- Using a known reference point Setting up the base station antenna above a known reference point, such as a geodetic control point or survey marker, offers a convenient method for acquiring a reliable reference position for the base receiver.
- Using NTRIP service You can connect to a NTRIP service to receive correction data. By logging the RTK positions and averaging them, it is possible to obtain a highly accurate reference position in a short amount of time.
- Using an online PPP post-processing service If there is no reference point or RTK network in your region, don’t worry, you can calculate the position of the base station by using an online Precise Point Positioning (PPP) service.
This approach is particularly suitable for users with an easy access to an accurate and up-to-date reference point.
This method proves beneficial for users situated in regions with access to an NTRIP service or RTK network.
Popular services include CSRS-PPP service, OPUS and APPS. Generally, these services recommend a minimal log file duration (usually 1-3 hours) and an ideal duration (typically 24 hours).
Some PPP services might require antenna calibration. If so, ensure you have a calibrated antenna like Calibrated Survey GNSS Tripleband + L-band antenna (IP67).
In this tutorial we will use CSRS-PPP service. You can receive a rapid result in about few hours. For the most accurate result, you might have to wait for 12-18 days.
How to determine the reference position of your base station?
Firstly, enable L5 with Septentrio Mosaic-X5.
- Connect the receiver to your PC via the USB port labeled as POWER+GPS.
- Open Septentrio web interface by typing 192.168.3.1 in your browser.
- L5 is disabled by default with Septentrio Mosaic-X5, thence we will enable L5 by going to Menu Bar–> Admin–>Expert Control–>Control Panel–>Navigation–>Advanced User Settings–>Tracking–>Signal Tracking.
Expand all satellite signals and select all band.
Click OK and save configuration.
Secondly, choose your preferred method to determine the geodetic reference position.
- Select an accurate and up-to date reference point, such as a geodetic control point or survey marker.
In this tutorial, we use the Senyals-geodesics of Catalunya.
Ensure that the reference point is situated in a location with a clear view of the sky, free from trees or other obstacles that may obstruct satellite signals.
- Setting up the base station antenna above the reference point. With the use of a tribrach and tripod this can be done very accurately.
- The location of your base station will coincide with the Geodetic point’s location. You can retrieve the geographic coordinates information from the geodetic point’s description. Ensure to incorporate altitude information by adding the height difference between your Antenna Reference Point (ARP) and the marker.
Thirdly, set the reference position as your antenna reference point static position.
- Go back to Septentrio web interface. In the menu bar go to GNSS–>Position. At Mode choose Static. At Reference position select Geodetic 1
- Now scroll down and expand the Advanced Settings.
- Continue scrolling down until you find Antenna Reference Point Static Position – Geodetic.
Set the latitude, longitude and altitude you obtained from previous steps.
Note that the altitude to be set should be the ellipsoid altitude (if you need more info about different types of altitudes you can check out tutorial about GNSS altitudes).
- You can set the coordinate with Degrees, Radians or DMS.
- Press Ok and Save the configuration.
Finally, enable correction data output.
- Select the interface you want to use to output correction data. If you are using one of the following plugins: Ethernet NTRIP Master, WiFi NTRIP Master, 4G NTRIP Master, you will configure RTCM3 output at COM2.
If you don’t know how to do it, refer to the tutorial How to configure simpleRTK3B as static base station.
- Congratulations! Now you can use your receiver as a static base station with centimeter level absolute accuracy. On the up-right corner, you will see the position mode is Fixed and with correction output.