Slow Telemetry update rate when Hex is in the air

Posted by Mike Wilson on September 2, 2013 at 6:48pm

I'm using the APM 2.6 with external compass in a DJI 550 with 3DR telemetry and the MinimOSD.  When looking at the telemetry via the OSD, the data updates properly when the Hex is on the ground but when in the air, there is a noticeable delay in telemetry updates via the OSD.  I'm running v3.01. 

Any suggestions would be greatly appreciated.

....Mike

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Replies

  • Mike Wilson September 8, 2013 at 6:50pm

    I relocated my OSD and also reloaded the SR0 and SR3 values.  The update rates are now working fine without having to connect to the PC telemetry first.

    Thanks for the help guys.

    • Anatoliy Pishenin > Mike Wilson August 24, 2014 at 9:46pm

      hi can elaborate on how you reloded the Sr0 and sr3 values, where are they located? how do i do this, i know this is an old post but im having the same issue

    • Mike Wilson > Anatoliy Pishenin August 25, 2014 at 8:45am

      In the Mission Planner, open up the Config/Tuning tab and select the Full Parameter List.  Save your existing configuration to a file and then you can edit each of your SR0 and SR1 values with the ones below.  Make sure you select the "Write" option after you have edited the values so that they are written back to the APM,

      SR0_EXT_STAT       2
      SR0_EXTRA1 10
      SR0_EXTRA2 10
      SR0_EXTRA3 2
      SR0_PARAMS 10
      SR0_POSITION 3
      SR0_RAW_CTRL 2
      SR0_RAW_SENS 2
      SR0_RC_CHAN 2
      SR1_EXT_STAT 2
      SR1_EXTRA1 10
      SR1_EXTRA2 10
      SR1_EXTRA3 2
      SR1_PARAMS 0
      SR1_POSITION 3
      SR1_RAW_CTRL 2
      SR1_RAW_SENS 2
      SR1_RC_CHAN 2
  • Mike Wilson September 4, 2013 at 8:43am

    I tested this morning and the telemetry updates are still slow when using just OSD in the air.  I'll try to use a ferrite or relocate the OSD and see what happens.

  • Mike Wilson September 3, 2013 at 5:37pm
    Thanks Bill. I'll see if these settings make any difference. The puzzling thing is that when using the OSD by itself, the update rate is fine until I'm in the air. Once in the air, there is a noticeable delay. This does not happen if the PC telemetry is also connected.
  • Mike Wilson September 3, 2013 at 5:12pm

    OK, I did some more testing and when I have the PC connected to the telemetry as well as watching the telemetry via the OSD, the updates are much faster.  If I only have the OSD connected, there is a noticeable delay in telemetry updates on screen.

    Could this be some sort of bug?

  • Developer
    Jani Hirvinen September 2, 2013 at 8:11pm

    Check also that you don't have anyone else closeby using same 3DR modems and especially on same channel. Another that I can think of is that you might have both telemetry modem and OSD listening+sending data. If you have telemetry and OSD connected, make sure that your RX line is disconnected from OSD.

    You can get nice small telemetry distribution board from our store if you don't have yet. In Here: Telemetry Distro board

    Bluetooth telemetry
    Long range telemetry set for all your UAV and UAS needs
  • Developer
    Bill Bonney September 2, 2013 at 7:27pm
    Do a log on rssi and remrssi of your radios. (Radio Signal Strength Indicator)
  • Developer
    Randy September 2, 2013 at 7:01pm

    It's very possible that it's because the CPU is overloaded and cannot provide the update rate that you'd like.  The CPU runs at about 60% when you're on the ground, about 75% when flying in stabilize and 100% when in Loiter.  It's very busy and the telemetry updates are lower priority than much of the rest of the code 'cuz you'd rather it fly than tell you what it's doing!

    This is all solved with the pixhawk of course which runs more than 10x faster.

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