If I use the GNSS unit with my Mavic 3E the first planned flight works great and records the correct information to carry out PPK analysis. However, if after the first task I proceed to carry out another mapping task, or manually take some extra photographs the .nav file for these extra photos or second mission are faulty and incomplete, so cannot be PPK processed. It is possible to recreate the .nav file from the .bin file using RTKlib, but that's not the point, it should just work. Any help appreciated.

PPK process the nav file ??

Yes I too have had the same issue. Sometimes if you pause a mission before it is complete, for a battery swap for example, it will do the same thing. If you take photos after a mission has finished I've also found some PPK software will get confused with the .mrk file having these extra photos at the end too. This can be solved by removing the added photos from the .mrk file. For solving a bad .nav file I really don't know.

LV_Forestry Posted at 6-29 14:25
PPK process the nav file ??

Im not sure whether you're asking if I'm using the nav file for ppk, whether you're asking how I ppk process using the nav file, or telling me something. Could you expand your question please? Thanks

djiuser_xp22w5ZmmFMg Posted at 6-29 23:40
Im not sure whether you're asking if I'm using the nav file for ppk, whether you're asking how I ppk process using the nav file, or telling me something. Could you expand your question please? Thanks

I always encounter issue with the NAV file from DJI. so iam not using the rover' NAV file for PPK but the Base Station one.
To go into more detail, below I put the screenshot of a Mavic3 NAV file. What is surprising is that it only mentions trajectories of 7 sat. 6 are Galileos and 1 GPS. And there is no mention of ionospheric correction. This is the guarantee of having a poor quality correction.




Below is the screenshot of the header of a serious RINEX file :



I generate them by following the tutorial here:
https://forum.dji.com/forum.php?mod=viewthread&tid=285647

Johnnokomis Posted at 6-29 16:05
Yes I too have had the same issue. Sometimes if you pause a mission before it is complete, for a battery swap for example, it will do the same thing. If you take photos after a mission has finished I've also found some PPK software will get confused with the .mrk file having these extra photos at the end too. This can be solved by removing the added photos from the .mrk file. For solving a bad .nav file I really don't know.

You don't need to correct them, you can use those of your base station, or those of the NASA data center:

CDDIS | | archive | gnss | data | (nasa.gov)

LV_Forestry Posted at 6-30 00:03
I always encounter issue with the NAV file from DJI. so iam not using the rover' NAV file for PPK but the Base Station one.
To go into more detail, below I put the screenshot of a Mavic3 NAV file. What is surprising is that it only mentions trajectories of 7 sat. 6 are Galileos and 1 GPS. And there is no mention of ionospheric correction. This is the guarantee of having a poor quality correction.

This ^^^
Same thing encountered. Use base nav file instead.

LV_Forestry Posted at 6-30 00:29
You don't need to correct them, you can use those of your base station, or those of the NASA data center:

CDDIS | | archive | gnss | data | (nasa.gov)

I don't have a base station, I don't need cm accuracy, <1m is fine. I use the rinex file provided by the Ordnance Survey base stations in the UK (Wales). I'm processing the lot in Emlid Studio, so the only .nav file I have is the one from the rover, Emlid tech support were great and had the solution of converting the .bin file into a .nav file, but that's really not the point, the DJI Mavic 3e should be creating correct files.

LV_Forestry Posted at 6-30 00:03
I always encounter issue with the NAV file from DJI. so iam not using the rover' NAV file for PPK but the Base Station one.
To go into more detail, below I put the screenshot of a Mavic3 NAV file. What is surprising is that it only mentions trajectories of 7 sat. 6 are Galileos and 1 GPS. And there is no mention of ionospheric correction. This is the guarantee of having a poor quality correction.

I've located the "Ephemeris" file that the Ordnance Survey produce daily for providing the .nav data required.  And it looks just like the serious RINEX file you pasted details of above with the ionospheric corrections etc.

Thanks for the help, I can at least work around the DJI fault now.

djiuser_xp22w5ZmmFMg Posted at 7-1 03:07
I've located the "Ephemeris" file that the Ordnance Survey produce daily for providing the .nav data required.  And it looks just like the serious RINEX file you pasted details of above with the ionospheric corrections etc.

Thanks for the help, I can at least work around the DJI fault now.

Your're welcome.

As far as i remember OS is providing 30s RINEX file which is not the best.
For the Nav file you can download the IGS/NASA mentioned above.

LV_Forestry Posted at 7-1 04:00
Your're welcome.

As far as i remember OS is providing 30s RINEX file which is not the best.

Well, it seems to be throwing an error even using a working OS file instead of the DJI .nav file. Comparing two .obs files directly (one working and one not) it looks like there is at least one section that's much shorter/incomplete... certainly something DJI need to address, because if the M3e isn't recording GNSS data correctly it's a bit of a flaw for their 'mapping' drone!

djiuser_xp22w5ZmmFMg Posted at 7-1 04:36
Well, it seems to be throwing an error even using a working OS file instead of the DJI .nav file. Comparing two .obs files directly (one working and one not) it looks like there is at least one section that's much shorter/incomplete... certainly something DJI need to address, because if the M3e isn't recording GNSS data correctly it's a bit of a flaw for their 'mapping' drone!
[view_image]

Weird, could you please share files so i can take a look

No me sale el archivo.nav en el log de vuelo solo el .mrk en un matriz rtk350. Me ayudan donde consigo ese archivo gracias

djiuser_wTqqPXXPgFmA Posted at 4-6 11:34
No me sale el archivo.nav en el log de vuelo solo el .mrk en un matriz rtk350. Me ayudan donde consigo ese archivo gracias

It's in your base station, ntrip provider, or download it from IGS.