Tiny RTK with PX4 firmware and QGC dedicated radio

BTW , is the survey in process set to finish when it reaches an accuracy of 1 mm by default or can it be changed ??

By default, survey-in is not configured, it is either configured by ground station (as a parameter in Mission Planner, hard coded in QGC) or by user.

The survey process can be set with Ucenter, and saved permanetly in configuration .

When you’ll connect the base NEO-M8P to the ground station you can check with Ucenter when the process ends and then connect with MP or QGC with the rover NEO-M8P and inject base datas .

I usually connect at first the base NEO-M8P to the ground station while I’m preparing the drone , making pre flight checks etc
When I start MIssion Planner after a couple of minutes the survey process is already finished and ready for injection.

That’s how I do too
I wait for the survey-in to be successfully finished but once I start QGC, it starts from the top.

With MIssion Planner it does not happend .

QGC restart the survey process , ask the developpers if there is a way to stop it.

I think it is hard coded in QGC
Will check with the developers

BTW any way to check the accuracy in QGC, with response to drone location ?
Does u-center have any sort of plotter to show show the base and rover and to measure its accuracy ??

There is a tool called “Deviation Map” that plots points in U-Center. You also have access to the 3D accuracy which is an estimator of the positioning precision.

When the injection process is going on, we could connect a uart to usb converter on the telem port of the BASE and have access to u centre right?

This is correct. Be careful to not apply several power supplies to the module though.

I connected the drone though mission planner and did gps injection through the "RTK/GPS inject " option and was able to get a fix within 2-3 mins (max). Was able to measure the accuracy too.

Some doubts with Mission planner RTK/GPS inject option

  1. I believe M8P portion with “Survey Acc” and “Time” is for survey in mode while Base position button is for setting the fixed base location

  2. What kind of MSG will occur in SVIN during the process, I was getting a:
    Survey IN Valid: True InProgress: false Duration…"

I would suggest that you first install the most current MP version 1.3.45. That includes a few bug fixes and enhancements to RTK.

SurveyIn: true and InProgress: false means that you hav set a valid base point and the system is ready to send corrections to rover.
If you want to record a new base point, then you need to clear the entry Enter Base Position dialogue box.
Then status will be Surveyin: false and InProgress: true after you connect the base module.
Surveyin Acc: defines the min accuracy and Time the minimum time the system is surveying. Both conditions need to be true before a base point is recorded.

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Could we wait for the survey-in process to be over in u-center( where the base shows status as TIME) and then inject using mission planner ? in the case, will the survey-in process in MP start all over again ?

No in MP the survey process will not start again .

During GPS injection a USB - UART converter to the TELEM port or Rover port of the base rtk module

Should I untick “M8P autoconfig” in the RTK/GPS Inject setup ?

In Mission Planner it does no difference if the base has complete the survey process.

Once configured with Ucenter , I just connect the base to the notebook of the ground station , after some minutes the survey is finished then I connect the drone with Mission Planner, inject the rtk data, wait for the red led to blink , when the led is stedy read you are done.

That’s is how I do too and it has worked quite successfully.
I guess we could use “M8P autoconfig” feature for setting the survey-in process through MP ?

If you use the drone telemetry to inject rtk correction via Mavlink, the base will be connected only with usb cable