Intorudction
This utility was tested with UBlox ZED-F9P GPS receiver and enables usage of its internal RTK engine. It is possible this works with other UBlox RTCM3-input enabled receivers but no guarantees.
To use this, you must have two receivers (one at base and one at "rover"), the one at base should be set to send RTCM3 messages. Don't forget to set its coordinates in TMODE configuration (static, surveying or moving)! The rover's receiver should be configured to enable RTCM3 input (by default they are). Both receivers are accessed through TCP/IP connections, that means you must install ser2net or similar utility to redirect serial port to the TCP/IP socket.
The utility has two modes - RTKLIB-compatible output (without deviation stuff, but with fix flag support) or pass-through, when you get just all stuff from receiver directly. It is switched by -p command line option.
Installation
Just clone the repository and compile/install with "make all"/"make install".
Usage
rtkzedf9p [-p] [-d] -b <BASE_RECEIVER_IP>:<BASE_RECEIVER_PORT> [ -r <ROVER_RECEIVER_IP>:<ROVER_RECEIVER_PORT> ] [ -l <LISTEN_PORT> ] [-t <RECEIVE_TIMEOUT> ] [-R <RESET_TIMEOUT> ]
-p - enables pass-through mode
-d - enables debug output
-b - sets base receiver's IP and port (in form "192.168.1.182:3003")
-r - sets rover receiver's IP and port (same)
-l - sets listen port for output
-t - set data receive timeout (for both rover and base), 20+ seconds is recommended
-R - sets timeout to send RESET command to rover's receiver if there is no RTK FIX (0 - disable), not recommended values less than 600 seconds
Troubleshooting
Enable debug output and run without -p, look at "quality" field (after altitude). It should switch to 4 (DGPS), 2 (FLOAT) or 1 (FIX) if you did set up everything correctly.
If not, check receivers configuration by U-Center. Connect to receivers by TCP/IP and check "messages view". The base receiver must output all kind of RTCM3 messages. Verify that it has 1005 or 1007 type messages as they contain the base's coordinates, if not - check TMODE settings (must be in survey mode to determine them automatically or static with coordinates set in form of "184159999" for "18.4159999" for latitude/longitude and in cms for altitude).
The rover receiver must accept RTCM3 input messages from the port you've connected it, and RTK mode enabled.
Sometimes the receiver can't get fix at all and requires reset to get it working. In this situation it is recommended to use -R option, the program will automatically do cold-reset on rover's receiver.