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Affordable way to integrate Reach M+ with DJI Phantom


(Konstantin) #83

AShot is available, but we are waiting for cables from China factory. they are on the way to us. I think after 10 days we will receive them.


(Tobias Dahms) #84

I also conclude that DJI logs are not suitable. Either the events are missing or if they are reliably there (is.Storing message) they have random offset up to 1,000 ms.

I’m almost finished with the script, but I don’t see the use of it regarding the current information aubout the logs. I hope someone comes up with a new idea.

With Arducopter I can reduce the message load to make some bandwidth free for a more reliable logging. I guess that is not possible with DJI?


(Konstantin) #85

New idea is using AShot )))))

Please see my logs. Timemark is in the middle of shutter in that logs.


(Tobias Dahms) #86

What about the onboard DAT files, are they still available or did DJI change that? Could please someone check that? I do not have a P4P… .

I think that this is our last chance to get the camera time from onboard data. Since the DAT files should have a higher data rate I have some hopes to get better information out of these files.

http://www.datfile.net/DatCon/retrieveV3Dat.html

http://www.datfile.net/DatCon/retrieveV3Dat.html

https://www.dji.com/de/downloads/softwares/assistant-dji-2-for-phantom


(Tobias Dahms) #87

Yes, of course. But I do not own a P4P and if I ever will I do not want to change something on it, because the only reason to buy it would be that it has a CE batch. I have a custom build drone which is far better for mapping than the P4P. And without camera and Reach it is cheaper than 380 €… .

But I think you have a great solution. Thanks for sharing the files!


(Konstantin) #88

Tomorrow I can share DAT file too.
Need I download it from Ph4pro or from iphone?


(Tobias Dahms) #89

From P4P via USB cable using the Assistant 2 for Phantom.

The procedure is described here:
http://www.datfile.net/DatCon/retrieveV3Dat.html


(Konstantin) #90

Ok, thanks, tomorrow I will download it.


(Hunter) #91

Has anyone compared/looked at the Litchi flight log time stamps? Here is how mine read out. Time in UTC, istakingphoto 0 or 1, and another timestamp unknown to me to 13 digits. Not sure if any utility here.


(Hunter) #92

A thread in regards to Litchi logs:


(Tobias Dahms) #93

Up to now I find the dat files most interesting. But up to now I did not find

  • the event which equals a picture or
  • the event which equals the led activation and
  • the UTC time or any comparable time

If some one has some ideas on these points I would be very happy.
Otherwise I will implement the version with the txt file but that is not very helpful I think.


(Konstantin) #94

Hi friend.

My DAT file of all flights 11 of March 2019.

I dont know which flight was test ((((


(Hunter) #95

From Litchi:

“The timestamp in the Litchi flight log can not be used for any precision work. It is the time when Litchi receives data from the SDK, which itself receives data from the drone. This means there is a delay between any of the drone’s action and the actual log time.”


(Tobias Dahms) #96

Yes, that is what I thought. I think the only potentially accurate log is the dat log. But I have no idea how to sync the log entries with UTC time and which message equals a picture.


(Konstantin) #97

Please see my DAT file above.
And you can compare it with AShot timemarks from UBX data.


(Tobias Dahms) #98

Yes, I’m comparing a dat file with known events.

I think the command we are looking for is " 9887 [L-CMD]call exec_fc_v2_special_function" I think this command activates/deactivates the led.

Unfortunately this is a generic description for several commands. In order to use the command my script must be altered or a script must be written to do the following things:

  • convert the dat file
  • load the image time from the exif of the images
  • get ms resolution in the converted dat file by comparing the gps time stamp and the time offset.
  • search for the corresponding [L-CMD… in the converted dat file
  • add the ms from the [L-CMD to the image time
  • write the image time to the obs file

It would be nice if someone could check Konstantins dat file whether my idea is good. It would but it would need some serious time to write the script. So if someone is interested in the solution please rise your voice…


(Tobias Dahms) #99

@timmyd I think it makes no sense to integrate the messages fom the txt file into the RINEX file. But I’m willing to stick to my promise if you are still interested. If you are interested please tell me which file (DJI, MapPilot) and which message I should use.


(WSURVEY) #100

Konstantin,

how long is the length of cable you supply with your board? How hard will spares be to obtain if someone breaks a cable? could you supply the board with some spare cables?


(Timmyd) #101

Hey Tobias, the original idea was that a very precise and consistent TS could be pulled from the log file. I thought this would get rid of any inconsistencies that exist using the LED blink sensor method. I have ordered the Ashot and it will solve my problems. I wanted to find a good solution in case someone could not buy the Ashot. But the Ashot solves two problems (inconsistent photo gaps and inaccurate time stamps.

To know if this is even worth pursuing we must first know if the FlightLog records are consistently precise by comparing the TS values provided by the Ashot and the TS values in the Flight Record. If there is a pattern of exact matching and consistency, then I think it would be a worthwhile endeavor. @VanavaraDigital is going to be checking that sometime so we can wait to see those results. Thank you for looking into this.


(Konstantin) #102

Please see photo.