M350 RTK & L2 RAW Observation data
1130 9 1-15 10:38
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sfgt
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Greece
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Hi everyone,

I tried to follow the guide of this link https://enterprise-insights.dji.com/blog/ppk-post-processed-kinematics-workflow with the difference that I use Μ350 with L2 payload and 3rd party GNSS receiver.

I tried missions with RTK Positioning both on and off. In both cases were created exactly the same files  and neither of them had a file with a PPKRAW.obs extension.

I would like to ask if I am doing something wrong or if there is a different workflow for L2 and a file with different extension created (that can used from 3rd party software like the one which used in the guide mentioned above).

I would also like to ask why RTK positioning should be turned off to record RAW GPS data. This can waste  a mission which for any reason the drone can lose communication with the contreller as a result no RTK corrections.

On several other platforms both from DJI or from other manufacturers RAW GPS data are stored either the RTK mode is on or is off so if any problem that appears during data collection can be fixed with PPK processing either with base station RINEX data or CORS network data.

Thank you!!!
1-15 10:38
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Panph
lvl.4
Flight distance : 5322589 ft
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Italy
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Wow. Following the topic.
If you're doing it right, dji has big issue with the workflow for L2.
I'm waiting for my own, now still using L1 with exact your workflow everytime: Rtk on while flying but every mission i do ppk with rinex for better processing.
1-15 11:43
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LV_Forestry
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There must be one file .RTK and one .RTB(if RTK is active).
You can let RTK active or not, the difference will be the RTB file.
Then to do PPK simply replace the RTB file by your own .RTCM, .UBX, .OBS file.

PPKRAW file is for photogrammetry device/mission.
1-15 12:07
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LV_Forestry
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https://forum.dji.com/forum.php?mod=viewthread&tid=285647

This workflow is also valid for L2
1-15 12:11
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sfgt
lvl.2
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LV_Forestry Posted at 1-15 12:07
There must be one file .RTK and one .RTB(if RTK is active).
You can let RTK active or not, the difference will be the RTB file.
Then to do PPK simply replace the RTB file by your own .RTCM, .UBX, .OBS file.

So if i want to take a PPKRAW file, i must select a photogrammetry mission?

And if i want to use the images from a lidar mission for photogrammetry in a 3rd party software, which raw file from Rover (drone) will i use to do the ppk process?
1-15 12:56
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LV_Forestry
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sfgt Posted at 1-15 12:56
So if i want to take a PPKRAW file, i must select a photogrammetry mission?

And if i want to use the images from a lidar mission for photogrammetry in a 3rd party software, which raw file from Rover (drone) will i use to do the ppk process?
For the photogrammetry mission you will have
-An OBS file (PPKRAW) which is the raw recording of what the GNSS receiver captured during the flight.  
-An MRK file which marks the timestamp of each image
-A folder with the images.  

With software like Emlid Studio (free) RTKLIB (free) RedToolBox (paid), you'll insert all of these things, plus the base station OBS file.  The software will geo rectify your images precisely.


If you use images from the LiDAR mission, you must use the .RTK file.  Its name is misleading because whether the RTK is fix float or single, it is always called RTK.

I have to check but you should also be able to use the PPKRAW.bin file by renaming the extension .rtcm3 then converting it to RINEX.  

You will ask me but then what is the difference between all these files, well it is the position of the receiver antenna.

.RTB base antenna
.RTK Main antenna
.RTS Sub antenna
.RTL lever arm
1-15 13:16
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sfgt
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LV_Forestry Posted at 1-15 13:16
For the photogrammetry mission you will have
-An OBS file (PPKRAW) which is the raw recording of what the GNSS receiver captured during the flight.  
-An MRK file which marks the timestamp of each image

MRK file created and in lidar missions.

Thank you very much for your help.
Edit:

Today i made 3 missions.


One photogrammetry without RTK and two lidar missions one with RTK correction an one without.


In photogrammetry mission folder created four files, except the images of course, with extensions MRK, RTP, RTK and SIG (no one PPKRAW.bin).


In the other two missions created files with exacty the same extensions.


The other strange that i noticed was tha in all missions MRK files the last row had value 50, which mean fix solution if I'm remember correctly (also in quality report all records was appeared as fix). I am 100% sure that i didn't turn on the RTK mode in two first missions (i saw warning message in controlles because of no RTK flight) an only in the final flight i turned on.


Pffff.... So confused!!!!





1-15 13:41
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Phillip Fox
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Australia
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Any luck with a solution? I'm having similar issues
5-23 15:38
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LV_Forestry
First Officer
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Phillip Fox Posted at 5-23 15:38
Any luck with a solution? I'm having similar issues

The OBS file is the .RTK file.
5-23 20:18
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sfgt
lvl.2
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Phillip Fox Posted at 5-23 15:38
Any luck with a solution? I'm having similar issues

Follow the instractions of post #6 (LV_Forestry provides in forum tons of informations). I use the RTKCONV to convert the .RTK file, from mission folder, to .obs and .nav file and then i use the emlid studio  to tag the fotos for photogrammetry solution. For lidar solution is enough to inport the rinex file from base station renamed to the mission folder contains names and ".obs" as file type
5-26 22:13
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