Drotek XXL(base) - XL(rover) & RTK FIX? (uBlox NEO-M8P)


#1

Hi,

I am really curious about Is there somebody out there who was able to manage stable (usable) RTK fix on NEO-M8P XXL base and NEO-M8P XL rover configuration. If yes how? (Configration, tip & tricks would be great)

I am fighting since weeks with this configuration but my best result is to get RTK fix for a few seconds.
Configuration is OK, everything seems to be working but RTK FIX does not come…The whole things seems to be very unstable and uncertain.

Please send your experiences (pro and contra all)
thank you

rugo

my best result:


#2

Here are a few things to try:

1.) Add a ground plane to each GPS like this one:


This is overly big, but it did allow for a much quicker RTK Fix.

2.) Try using only GPS satellite constellations (not Glonass and the others)

3.) Make sure your measurement rates are at 1 Hz

4.) Make sure in you’re in an open area not next to tall buildings and trees

I haven’t explored other things that would impact the solution such as filtering satellites with SNR values below 40 and elevation angles below 5 degrees. (Not sure if that’s even possible with the u-blox interface. It is with another system I use.)


#3

Hi rrr6399,

thank you for reply.
What is the result on your side? Can you manage stable RTK fix?
How long is spen until you get RTK fix? How stable it? What happen if rover is moving?


#4

I have obtained stable fixes on a moving platform. I’ll perform a test this week with the DroTek XL as base and rover on a copter to verify and to better characterize the results for you.

In the past, I had used another RTK (Reach, M8T) as the base station most of the time, but I recently started using the DroTek XL as the base with the ground plane and have obtained stable results in a static scenario for 20 minutes or so and fairly quick fixes once the base GPS obtained the time averaged GPS position to the specified 1 m accuracy.


#5

Hi Everyones,

I am really curious if there is somebody who ever was able to manage stable RTK fix with this configuration.
My expereience is quite depressing.
RTK fix just available in very-very ideal environment and after more than half hour convergence time …then if rover starts to move RTK fix turns back to FLOAT and still should wait fifteen minutes to get RTK again.
Practically it is unusable (for RTK/cm precision).
Well, I would like to see evidence(s) this stuff is really able to give promised (RTK/cm precision) performance otherwise I should say it is great for like ordinary GPS but NOT for RTK.

rugo


#6

Same for me.
Even with a ground plane, the right configuration and a perfect area for flying, I still got a pacc= 1.5m.
I’m disappointed, becausee I’m looking for ~40cm precision.
Can you help please? Do you have any other propositions?


#7

In CFG - DGNSS set differential mode to “RTK float: no attepst are made to fix ambiugities”
This way your receiver will always work in float mode.
After about 30 minutes from receiving RTCM correction you will get 0,4 - 0,7 meter precision which more or less will be stable.

regards
rugo


#8

Thank you! I’ll give it a try!

What messages do you use in the configuration of the GPS RTK for PPK (not RTK)?
Can you confirm mine (NAV, RXM, MON, NMEA, and RTCM) or share your configuration?
Thank you!


#9

Sorry i do not use PPK just fighting with RTK.
What do you mean with PPK?