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Multiple 3DR 915Mhz radios - one for primary ground station and others for remote spotter personal on Adroid photos

Posted by Christopher Haddad on October 26, 2014 at 12:48pm

Hi All,

Looking for some feedback on our setup.

We are using this solution for long range remote sensing flights. We have one 3DR 915Mz radio setup with our ground station configured for two way communications with the UAV.  We would like to provide Adroid phone's to our remote spotter personal with a 3DR radio, but only setup to receive.  As we do not want the remote spotter to accidentally send any communication back to the UAV during the mission. 

What is the best practise to setup a radio to receive only? And are there any settings to help improve the range?

Thank you.

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Replies

  • Pete January 16, 2015 at 3:47pm

    Hi,

    I'm by no means an expert with these radios, but I've been wondering exactly the same thing (with the 433MHz version). According to this you achieve this by setting the duty cycle to zero on the R/O unit. There's probably loads of ways to set this - but I'd go through the Radio Config section within MissionPlanner or APMPlanner2.

    I haven't had a chance to try it yet - I'm slightly sceptical as I would have thought that there might be some 'negotiation' in the MAVlink protocol.

    I'll try this when I get and change and post back - please let me know how you get on :)

    Cheers

     

    • Pete > Pete January 16, 2015 at 4:13pm

      My spare radio was right in front of me so I just gave this a go!

      Good news - it appears to work!

      I've got a the quad powered on next to me, with the Rx/Tx unit on my Android connected with DroidPlanner. The RxOnly unit (Duty Cycle set to Zero, all other config matches) is connected to my PC running Mission Planner. Telemetery is streaming through to both PC and phone :)

      Only 2 things I've noticed from (Rx-Only) Mission Planner:

      • The Pixhawk parameters are not downloaded upon initial connection (not surprising as I guess these are requested by the app) - fortunately you can click cancel on this dialogue and it continues as normal.
      • The Mission Planner log window (showing the real-time log stream) seems to show quite a few lost packets, more so than normal - my guess is that the radios are capable of re-transmiting if requested, but obviously the Rx-only unit cannot request this. I'd have to read up a bit more but AFAIK it probably wont cause any major issues.

      Now I just need to go fly it!

      • iskess > Pete August 5, 2015 at 10:04am
        I tried this with two Mission Planner computers and couldn't get the receive only one to connect. Same net ID, Duty Cycle to zero. Is there anything else I need to do? Does it matter which connects first?
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