Discussions

Multiple radios on the same network ID

Posted by Helldesk on April 7, 2012 at 10:21pm

Do the 3DR radios support having more than two modules communicating together? Specifically the simplest possible case of having two (2) units listening on the ground, only one (1) in the air and only one of the ground modules actually sending data TO the air unit. The idea is to integrate one in a Turnigy transmitter to display vital stats so one could fly with some telemetry even without a full ground station with you.

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Replies

  • Pete January 22, 2015 at 1:46pm

    Hi All,

    I've been looking into this and have had some success with a Rx-only radio, i.e. match NetID and set Duty Cycle to zero. See this this DIY drones thread. Multiple 3DR 915Mhz radios - one for primary ground station and oth...

    "

    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!
    "



    Cheers

  • Earl April 10, 2012 at 9:52pm

    I also need point to multi-point. I want the mission planner AND my er9x TX to display the mavlink data like the Xbee's I use now ! I really want the 433mhz because our balloon will be 20 miles strait (almost) up. We Will be using yagi antennas on the ground to track the signal.

    Launch is Saturday 4/14/12 so I hope the radios will be here by then. Otherwise we are using the 60mw 2.4ghz Xbee's. And 24db grid antennas on the ground. The primary tracking is on 148-150mhz satellite radio modems. (I know, overkill and we have to time the launch for the sats !)

    The group is quite excited. An APM2 will be on board with a 720 HD camera with 16Gb memory card. I hope the APM2 will measure attitude with the barometer as well as the GPS (which may crap out at 18000 meters).

    Mission planner on ground on laptop with internet access.

    I hope to have an ATV live video TX on board also for live video. (I am N8TV) Channel 59 cable - 439.25mhz.

    I will post more after flight.

    Earl

    P.S. This is in Edgewood NM at 9 am if you are near.

  • Developer
    Andrew Tridgell April 7, 2012 at 10:29pm

    not really, no.

    As a hack you could make it work by setting the DUTY_CYCLE to zero on one of the ground units and also setting NUM_CHANNELS=1. That would do what you want, but many countries require that you use frequency hopping above a certain power level, so it may not be an option.

    The current TDM system is really not meant for more than 2 radios. We could add support for this, but I doubt I'll get to it soon. Feel free to start hacking on the code though! The hardware can definately do it, we'd just need some software support for dividing up time into more than two sets of slices.

    Cheers, Tridge

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