RTK
The GNSS Compass internal GNSS receiver(s) supports RTK GNSS which uses correction data (RTCM messages) from a nearby base station to provide accuracy of up to 0.01 m in real time. An RTK system requires additional infrastructure equipment to generate and receive corrections data, and is not practical for all applications.
There are two different methods for receiving RTK corrections:
- Network
- Radio modem
For applications where GNSS Compass can achieve internet access, network RTK corrections (NTRIP) are recommended.
For applications that are unable to access the internet, radio modems can be used to communicate between GNSS Compass and the base station, see Radio Modem RTK Corrections.
Network RTK Corrections (NTRIP)
NTRIP can be configured as follows:
-
Using the GNSS Compass web UI NTRIP Client in the Configuration Menu.
-
Using the GNSS Compass Manager application, select NTRIP Client under the Tools menu.
-
Using the Spatial Manager for Android application. This is convenient for field testing or when temporary RTK corrections are required, for example for performance trials. Download from the Google Play store.
Any of these NTRIP clients can connect to a network RTK service to stream RTK corrections to GNSS Compass. This requires that the client is connected to the internet, and a valid subscription with a local network RTK service. Contact Support if you need assistance in setting up for network RTK corrections.
Radio Modem RTK Corrections
|
Trimble R4 Base Station |
Trimble TDL 450L Radio Modem |
Base station radio modem RTK corrections require both a base station and a radio modem receiver. The base station is set up at a fixed location and transmits corrections to the radio modem receiver that is connected to the mobile GNSS Compass unit (the “rover”). The radio modem receiver and GNSS Compass unit must remain within radio range of the base station to receive these corrections. The base station should be located no more than 50 km from the GNSS Compass, and ideally closer. Advanced Navigation recommends contacting a local surveying company for assistance setting up a base station.
RTCM Messages
The following RTCM v3.3 messages are recommended for the internal GNSS receiver in GNSS Compass.
| Message Number | Description |
|---|---|
| 1005 | Stationary RTK reference station ARP |
| 1006 | Stationary RTK reference station ARP with antenna height |
| 1007 |
Antenna descriptor |
| 1033 | Receiver and antenna description |
| 1074 | GPS MSM4 |
| 1075 | GPS MSM5 |
| 1077 | GPS MSM7 |
| 1084 | GLONASS MSM4 |
| 1085 | GLONASS MSM5 |
| 1087 | GLONASS MSM7 |
| 1094 | Galileo MSM4 |
| 1095 | Galileo MSM5 |
| 1097 | Galileo MSM7 |
| 1124 | BeiDou MSM4 |
| 1125 | BeiDou MSM5 |
| 1127 | BeiDou MSM7 |
| 1230 | GLONASS code-phase biases |
| 4072.0 | Reference station PVT |
| 1002 | Deprecated (supported but not recommended) |
| 1004 | Deprecated (supported but not recommended) |
| 1008 | Deprecated (supported but not recommended) |
| 1010 | Deprecated (supported but not recommended) |
| 1012 | Deprecated (supported but not recommended) |
| 1019 | Deprecated (supported but not recommended) |
| 1020 | Deprecated (supported but not recommended) |
| 1044 | Deprecated (supported but not recommended) |
| 1045 | Deprecated (supported but not recommended) |
Recommended RTCM v3.3 messages