433mhz 3dr telemetry range issues

hi all,

i am using a 433 mhz, 3dr radio telemetry. i have thought 433 mhz to be of good frequency for a longe range radio telemetry. however when i am  using it in the field, i find the range of the telemetry module to be no more than 30 meters radially. 

i would like to know how to increase the range on the module. i am using the supplied omni antennas.

thanks in advance

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  • Hi all,

    I have narrowed down this problem that people seem to be having with their telemetry radios giving very poor range.  It appears that the Android apps Tower and Droid Planner both return significantly reduced range compared to the very same 3DR radio unit plugged into a PC and using Mission Planner.

    This is very unfortunately as I was hoping to replace PC groundstations with a simple, lightweight tablet with long battery life etc etc.  Does anyone have any clue as to why this is happening?  Maybe something to do with how the Android USB works?  I tried to use a micro to full size USB adapter in order to run a full length USB cord to put the telemetry radio higher into the air in an effort to gain more range, but the telem radio no longer worked with this wire so I suspect the 3DR supplied micro to micro USB is special for the telemetry radios.

    • Interesting.

      I think I am having a similar issue. On my first maiden auto mission flight I was holding my tablet with the radio connected in my hands and already got a "connection lost" message when my Iris was just ca. 40m away.

      The mission was continued as I set the failsafe in that way.

      I know the post is some months old, but are there any updates how it's finally solved?

      • Hi Christoph,

        We are wanting to use the tables in a commercial solution at Agribotix so we want them to be foolproof.  We have greatly improved the performance through a few channels.

        Firstly we tested multiple tablets and some are much better than others.  We settled on the Nexus 9 as it was a good priced tablet that performed as well as a very high end Nvidia tablet.

        The second thing key thing we did was use a bluetooth adapter instead of the supplied USB cable.  Even when powering the telem radio with it's own lipo, it still worked much better over bluetooth than USB.

        Lastly we specced the Hobbyking 500mw 915mhz modules instead of the 3DR 100mw 915mhz modules and upgraded our ground antennas to a nice 5dbi L-Com omni.  It's unfortunate that the hardware upgrades are necessary but in our testing that's what's required to fly 1km with good signal quality using the tablet solution.

        Now give me a PC and a pair of 100mw 3DR radios and it will go 3km or more with great signal quality.  I really hope the next version of Tower figures this out.

        • Has anyone tried using an RFD900 telem radio? You would need to use an external battery.

          • Yes we tried the RFD900 but abandoned it because it's a pain to wire and setup correctly, isn't as reliable to connect, and doesn't really perform any better than the 500mw unit with a good L-Com antenna.

    • check what voltage your device outputs in  OTG mode when the radio is on, is it true 5v ?

      • I am not sure of the voltage as I haven't measured it yet, but I get the same exact performance when using an Event38 bluetooth bridge instead of the 3DR radio which has its own internal battery.

  • http://copter.ardupilot.com/wiki/common-3dr-radio-version-2/

    good read and good luck

  • verify that you have correct antennas, not 5.8ghz, 2.4ghz, or 900Mhz..

    you should have >1Km on stock settings.

    DO NOT up output power to compensate for defective or wrong antenna, you can easily destroy transmitter transistor.

    also, try telemery alone, away from a certain place or computer - some hardware can be very noisy around those freqencys.

    • The telem radios usually come set at 20dBm. If he isn't sure he has the right antenna, then there is a lot of work to be done. Btw, I doubt VSWR could be off enough to do any damage at 100mw. Far worse to have no antenna and get all the RF reflected back into the Power Amp.
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Aug 25