Time from Float to Fix

Hello,
I would like how long does it take to go Fix since you start the system?
And also , How long does it take to go Fix if in flight the drone looses connection?

If I am using Pixhawk with its own telemetry and I use this telemetry to send the corrections to RTK rover, What happens with normal loss of telemetry data?

I am really interested in buying a set but I am not sure about it.

Thanks
Alberto

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Hello Alberto,

We measured an average of 4-5 minutes in order to get the fix. U-blox has released last week a new firmware that apparently enhances this time, though we haven’t tested it yet.

If drone loses connection during flight float solution is maintained for a couple of minutes. It is difficult to say how long it can take to go back to fix solution because this really depends on the signal conditions.

As said before, if telemetry link is lost, M8P goes back to float solution and ends up going back to single solution if no differential data is sent for several minutes.

Feel free to ask any question about the system!

Thanks Kevin.

4-5 min is a good time for getting Fix, but if I am in the middle of a flight, is a lot of time.

So I understand that if the telemetry fails just for a few seconds, the rover uses the last correction known, for a few seconds until the connection is back.
I am planning to mount this RTK GPS on a Multicopter and I would like to know if it is going to be useful to me. If the dron is flying in the middle of a mission and losses the correction, I am not going to have a perfect positioning.

Two questions more:
How can I know when is Fix or float during flight?

Do I need to load an special firm on the Pixhawk?

Thanks
Alberto

Hello Kevin:

My special worry about the tinyRTK is: how consistent is the status FIX?
I have tried other RTK and the main problem is the siystem is loosing the status FIX every few minutes and I have to wait till the system is again in status FIX.

Using the Tiny RTK with PixHawk and sendind the corrections throught the telemetry modems with the rest of MavLink sentences.
Is this setup stable?
Can I be working all day with the Tiny RTK with the status FIX with just one or two times loosing the corrections and waiting to be FIX?

Please answer the two messages
Thanks a lot

Yes you are right, it can be long if you are in the middle of a flight.

Yes the rover can hold the fix for several seconds if telemetry fails. It can go up to a minute, depending on the conditions.

During flight, this depends, are you using Ardupilot ou PX4? PX4 driver already lets you know whether you are fix or float. On Ardupilot, the driver needs a small adaptation.

You do not need to load a special firmware on Pixhawk.

Fix consistency depends on your setup, what antennas do you use? Do you have a ground plane? In open-sky conditions our tests held fix consistently. u-blox constantly releases enhancements to improve it.

Hello Kevin,
Thanks for your honest answers.

Flying with 433 telemetry modules and dipole antennas I have 98% signal all the time even flying 3 Km far.
I do not loose the signal any time at all during the flight, My telemetry logs are totally complete afer flyght.

Do you think is going to be good enought to use Tiny RTK??

Yes if telemetry is consistent that is a good point. It should be ok then, choose good antennas and use a ground plane!

I am using QGC with Pixhawk and doing GPS injection
The survey in process takes about 20 mins to complete and then getting a fix takes about 2 mins
Any way to reduce the time ?

Survey time depends a lot on the precision asked , if you put 5 meters for suervey it will take a couple of minutes but is you unput 1 meter it will take much much more and eventually it will never complete if the received signal is bad i.e. if you are inside a building.

I had set the min observation time as 10 sec and position accuracy as 10 m but even the in QGC, the survey in process finishes when the accuracy reaches 1m

Is it standard of QGC ??

QGC automatically configures base station for 3 minutes observation time and 1 meter accuracy. I think this is hard coded.