SkyDemon Forums

Rate of GPS data in gpx file

http://forums.skydemon.aero/Topic36883.aspx

By MarkFrecker - 4/14/2024 12:20:02 PM

Dear SkyDemon community,

I have a question regarding the data files which are created after the flight.
I use an iPad mini 5 with an external GPS receiver from DUAL. It is set to a refresh rate of 1 Hz. 
After a flight with a logging time of about 1h09m the created gpx file does not contain about 4100 entries but only about 1300.
The distance between the entries is between 0 and 6 seconds,
Last flight as an example:
     124x 0sec (meaning the same time from one entry to the next one)
     212x 1sec
     198x 2sec
     108x 3sec
     99x 4sec
     554x 5sec
     6x 6sec
     1x >6sec

Why I do not have an entry for every second?

Please respond.

Happy flights 
Mark

By MarkFrecker - 4/15/2024 9:00:48 PM

Tim Dawson - 4/15/2024 3:07:05 PM
They are logs of your flight, that doesn't mean we are going to log every single input from your GPS.

At present (this could change) we log a position every 5 seconds, unless there is a significant change in your track or speed or altitude, at which point we log extra snapshots.

Hello Tim,

thank you for your quick answer.

I just thought if I use this data for overlays for a video it is maybe better to have data points every second - at least it looks better when I compare videos made with the SkyDemon data with videos made with data from my garmin fenix watch (which is set to a frequency of 1 Hz to collect data points) - especially the heading turns smoother. For all other data one position every 5 seconds seems to be good enough.
Unfortunately the height information is worse with the fenix data - when landing at the same airport where I took off I am often about 10-15 m higher :-(. With the DUAL GPS receiver it is more accurate.

But your answer makes reason - for at least 99.9% of the users and applications this is good enough.

Thank you again for your answer and for the well-made software with all its great improvements over time - I enjoy every second with your software including planning and flying :-)! I appreciate all of your work and effort.

Best regards
Mark

P.S. Maybe I will be at the aero Friedrichshafen this year - then I could come by to see you personally.