Going for distance on the 3dR Telemetry modules.


For the longest time I've only been able to get about 500 meters out with my stock 3dR telemetry modules. No matter what settings I tried I couldn't get any further. There's been discussions in the forum about the specs of the radio modems and how far you can go. I've even swapped out telemetry modems thinking I might have fried one. Finally I broke down and ordered some parts from Servo City and built an antenna tracker. Then utilized a 900mhz -8dbi patch antenna I was using for FPV before I switched to 5.8ghz. Today I finally made it out to 1.3km! This is with the patch antenna and a stock antenna onboard the plane. 

I had to reduce my telemetry speed clear down to 2400 baud before I could get a relatively solid signal back to the ground station. Anyone have any suggestions for 3dR telemetry radio settings? I'd love to make it out to 2 km on the 3dR modules and still have a solid telemetry link. I've been eye'ing the RDF900's for quite some time. As much as I'd love to throw more power at my signal I'd like to squeeze what I can out of what I have. 

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  • Developer

    Hi Scott,

    You should also plot the remnoise. The drop outs shown in your graph happened when you still had plenty of signal, which may indicate your remnoise is the limiting factor. If you add remnoise to the graph you'll be able to tell if the problem is the remnoise.

    Cheers, Tridge

  • I have done 800m with stock antenna, still receiving telemetry but I was very high without any object between the drone and me. On the ground, inside dense forest we got 50m~ no more.

  • 100KM
    Scott, I've done 3 km before on the old xbees. You're right, just make your own antenna. I built custom dipoles and they work well.
  • @Phil - This last go around I had the AT mounted on top of my SUV's tail gate. A good 2 meters off the ground. 

    @Michael & Rana - I keep looking at the RDF900's but haven't made the investment yet. I'm taking IBCrazy and a few others suggestions.. You don't need to throw more power at it. Just a better antenna. 

    @Graham - I've swapped both antennas before, even swapped vendors *sneeze rctimer*. I have two 900mhz 3dBi antennas from Hyperlink I've tried. Including an antenna off an old pair of 900mmhz XTends I have.

    @John - I've seen the dronecell and a few other things. Right now my range goal is 2.5-3km. As it stands right now at my test range at 2.5km I'll hit a mountain. I'd like to have telemetry that goes further than my 2.4ghz Futaba radio I've been using. At least then if I had to I can hit 'RTH' button in MP and it'll work. After I work through this I'll probably go over to a LRS and begin the cycle over again. 

    @Andrew - I've been following that guide and plan on going out to my main field today. At my main field, since I'm in closer, I'll actually reduce my power settings and run some tests. When I head out to the ranch I'll increase the power and give it a whirl. This last go around looked promising and did get me out pretty far. The 3dR page boasts about 1mile on the setup. So far with a modified setup I'm 3/4 the way there. Figured I'd reach out to the community for some pointers.

    Here's my graphs from the 1.3km flight. 


  • If you need serious range, are have good data coverage in your flying location, an onboard 3/4G hotspot with a RN-174 will give you range of the coverage. The cheapest I've found is 30 bucks a month in the US though. Thanks tommy for figuring this out!

  • Developer

    Hi Scott,

    It is possible to get a lot more than 1.3km with omni antennas. As I've mentioned before, the key is to get a tlog at short distance, then at longer distances, showing the signal and noise at both ends of the link.

    Have a look at the bottom sections of the 3DRRadio page. That will tell you what graphs you need to look at to work out what is wrong, and what you need to post if you want someone else to take a look. Make sure you post results for both a 1m test and a longer range test.

    Cheers, Tridge

  • 13dbi yagi at ground and 5 dbi rubber duck other side.

  • Moderator

    Scott, what MHz radio's are you using, I read on somewhere else on the 'net of someone having been shipped the 433MHz antenna with a 915Mhz radio (or vice versa)?

  • Moderator

    With what antennas, Rana?

  • Scott, it is quite unfortunate that both the RFD900 modules did not give you range more than 500mt with stock antenna :(

    You should seek help of Seppo, may be he would suggest to send the modules back to him.

    I achieved 56km range @19200 baud.

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