[DJI-log-discuss] Getting start time of a DAT file?

[David Kovar]

Greetings,

I think you are looking at the IMU record rather than the GPS record. Or, rather, DROP is confusing the two.

You might consider using DatCon to turn the files into CSV and then parsing the CSV files.

Also, what is your use case? Are you doing this as a one off, or do you need to support all of the DJI products? Getting unencrypted log files from newer models is very hard.

Regards,

-David



David Kovar
CEO, Founder URSA Inc.
Cell: 650-278-1774




> On Jan 24, 2022, at 10:02 AM, John Burns <john at unixnerd.co.uk> wrote:
> 
> I wonder if I'm misunderstanding something basic? I should add I know little about drones as we normally subcontract drone surveys so I don't own one.
> 
> I have a drone file FLYxxx.DAT and I've been decoding it, the GPS record I'm using looks like https://www.google.com/url?q=https://github.com/unhcfreg/DROP/blob/master/modules/GPSPayload.py&source=gmail-imap&ust=1643641383000000&usg=AOvVaw06g7rc93jaSbARXfOF791D which seems to have a different format to the GPS(gps#) record on https://www.google.com/url?q=https://datfile.net/DatCon/fieldsV3.html&source=gmail-imap&ust=1643641383000000&usg=AOvVaw0Zodp1Btkpj6VO6ACcZ0w0.
> 
> Sorry if this is a stupid question :-)
> 
> --
> John G.Burns
> 
> 
> ________________________________________
> From: DJI-log-discuss <dji-log-discuss-bounces at us.live555.com> on behalf of David Kovar <dkovar at ursasecure.com>
> Sent: 24 January 2022 14:31
> To: Discussion of DJI's log file formats
> Subject: Re: [DJI-log-discuss] Getting start time of a DAT file?
> 
> Greetings,
> 
> DATCon has a good list of all the records and their fields: https://www.google.com/url?q=https://datfile.net/DatCon/fieldsV3.html&source=gmail-imap&ust=1643641383000000&usg=AOvVaw0Zodp1Btkpj6VO6ACcZ0w0 (Look for the GPS record.)
> 
> Regards,
> 
> -David
> 
> David Kovar
> CEO, Founder URSA Inc.
> Cell: 650-278-1774
> 
> 
> [cid:8993EDD1-F627-4A82-871D-951B696571BD]
> 
> On Jan 24, 2022, at 9:09 AM, John Burns <john at unixnerd.co.uk<mailto:john at unixnerd.co.uk>> wrote:
> 
> Thanks for the reply! If you have more details that would be very helpful. I'm reading a GPS record to get lat/long/height, according to the DROP source code it has many other fields but not time.
> 
> --
> John G.Burns
> 
> 
> ________________________________________
> From: DJI-log-discuss <dji-log-discuss-bounces at us.live555.com<mailto:dji-log-discuss-bounces at us.live555.com>> on behalf of David Kovar <dkovar at ursasecure.com<mailto:dkovar at ursasecure.com>>
> Sent: 24 January 2022 14:06
> To: Discussion of DJI's log file formats
> Subject: Re: [DJI-log-discuss] Getting start time of a DAT file?
> 
> Greetings,
> 
> There is a GPS record with the real world timestamp (in UTC, I think.) You can work backwards from that to get the start time of the logging.
> 
> If you need more detail, let me know.
> 
> Regards,
> 
> -David
> 
> David Kovar
> CEO, Founder URSA Inc.
> Cell: 650-278-1774
> 
> 
> [cid:8993EDD1-F627-4A82-871D-951B696571BD]
> 
> On Jan 24, 2022, at 8:39 AM, John Burns <john at unixnerd.co.uk<mailto:john at unixnerd.co.uk><mailto:john at unixnerd.co.uk>> wrote:
> 
> Hello. I've managed to write some Java code to import DAT files into my specialist GIS package. I'm struggling with time though.
> 
> I can see that time increments in milliseconds come from the "tick"/600, but I can't find any way of getting the start time of logging. I've been using the DROP (https://www.google.com/url?q=https://www.google.com/url?q%3Dhttps://www.google.com/url?q%253Dhttps://github.com/unhcfreg/DROP%2526source%253Dgmail-imap%2526ust%253D1643636411000000%2526usg%253DAOvVaw2XT1gUceOqvTjo3pKDC-NM%26source%3Dgmail-imap%26ust%3D1643638221000000%26usg%3DAOvVaw2HZifjtTYycqVrMleSEzgF&source=gmail-imap&ust=1643641383000000&usg=AOvVaw1HMql7OP7gQvvf9dtuEaOk) python software as my guide in this. It seems to use the file's OS time stamp with the obvious problems that entails.
> 
> Any help is appreciated :-)
> 
> --
> John G.Burns
> 
> 
> --
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