Discussions

Re-establishing telemetry

Posted by Duffy on February 13, 2015 at 12:40am

Often I would loose telemetry and it is not possible to re-establish the link while the system is flying.

 Especially with auto missions it is rather frustrating if the system goes out of range and then there is no telemetry for the rest of the flight.

 Is there something we can do to make sure telemetry link can be re-established

 Thanks

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Replies

  • Marcin Krawczyk February 13, 2015 at 1:46am

    Show your config (screen from 3DR Radio config tool would be OK).

    • Duffy > Marcin Krawczyk February 13, 2015 at 3:01am

      Marcin,

      Here it is, I have the same settings on the aircraft

      thanks

       3702547810?profile=original

      • Marcin Krawczyk > Duffy February 13, 2015 at 3:19am

        1. Are you limited by local radio regulations?

        2. Air speed MUST BE GREATER than Baud.

        3. Change NET ID to anything different than default.

        Best is (if local restrictions do not apply or just for checking):

        - Min Freq 414000

        - Max Freq 454000

        - # of Channels 20-30

        - Duty Cycle 100

        • Duffy > Marcin Krawczyk February 13, 2015 at 3:27am

          Thanks,

           I dropped the baud, but now it doesn't connect at all,

           Also is there any reason to adjust duty cycle when using low airspeed?

           Thanks

          • Marcin Krawczyk > Duffy February 13, 2015 at 3:40am

            APM/PX connects at 57k by default, so you can't drop baud without prior reconfiguration AP.

            With low duty cycle you're limiting bandwidth (modems can transmit only through 60% of available time).

            • Carsten Groen > Marcin Krawczyk February 22, 2015 at 11:09am

              Marcin,

              I'm using 32K airspeed and 57.6 for the serial port in my system. I primarily send data in one direction. I use CTS from the modem to let the airborne system wait for the modem to be ready (the signal is always in idle so transmission is immediate), this seems to work perfectly ok ?

               

              • Marcin Krawczyk > Carsten Groen February 22, 2015 at 11:15am

                Airspeed should be higher than UART speed.

                IMHO you should start with default settings and adjust no more than one parameter at once, until you'll find which one leads to troubles.

                • Carsten Groen > Marcin Krawczyk February 22, 2015 at 11:20am

                  Marcin,

                  I'm not sure I understand the requirement for airspeed being higher than serial port. I fully understand the need if you send at full speed over the serial port, the airspeed can never "catch up" with the data. But, if you only send bursts of datablock over the serial port (small packets) there should be no problem delivering the data.

                  Thats how my system works anyway, and no problems seen with this approach.

                  I just wanted to be sure that there was no problems "hidden" with the way I do this in my own system (using Hope modules and 3DR radios)

                  EDIT: Marcin, I was not the orignial poster to the question, I was just worried that there was a deeper reason not to use a lower airrate than the port rate.

                  Sorry for the confusion ;)

                  • Marcin Krawczyk > Carsten Groen February 22, 2015 at 11:22am

                    If you're sure that buffer wil never overflows - go ahead.

                    I've gave you way to investigate your issue.

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