How to improve FPV and Telemetry Range

Posted by Felipe Rabat on March 29, 2015 at 8:03am

Here's the deal; yesterday, while shooting this video, I noticed my telemetry and FPV video keep going out after I get the Y6 100~150 meters (a meter is about a yard, for our American friends).  I am using the standard whips antennas that come on the 3DR telemetry modules, and I am using 3DR's circular polirized antennas on both the FPV transmitter as well as the Black Pearl monitor (this one has dual receivers).  Here is how my antennas are mounted in the Y6:

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Here's how I set up the antennas in the diversity receiver in the Black Pearl:

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Anywaym what is the best solution to increase range in communications?  Differente placement of the antennas?  Maybe point them down instead of up?  Use a Helical antenna in one of the diversity receiver and keep the mushroom in the other?  How about telemetry?  I have read that the antenna used by 3DR are not tuned, but I have not found any better solutions...  Any advice?

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Replies

  • DG May 2, 2015 at 11:46am

    Here's a pic of the 3DR radio with one of the 915 antennae attached on my 'dixie cup' quad.

    e0VXP9W.jpg

    For some reason I can't get the radios to connect to my phone anymore using Tower, so I set the other radio/antenna sitting in the picture window on a chair.

    KehVmA1.jpgI then did a test mission, max distance from GCS was 312m per MP. The signal never dropped below 92%. With the 3DR units, it would constantly drop in and out after only maybe 100m, and would never work half that with one radio inside behind a window. There is also a large tree in front. 

    So for my situation, changing to a true 915 antenna made all the difference. 

    2015-05-02 13-09-59.tlog

    • DG > DG May 2, 2015 at 6:17pm

      With the GCS outside (laptop and 3DR radio) sitting on the picnic table under the tree,  the same mission resulted in nothing less than 97% signal. It actually is better than the Frsky X4R on the copter.

    • Felipe Rabat > DG May 3, 2015 at 6:30am

      So basically, your recommendation is to jist get a set of 925 MHz antennas?  I found a couple in Amazon that I could grab...

    • DG > Felipe Rabat May 3, 2015 at 12:10pm

      All I can say is with these antennae on the 3DR radios, the signal strength out to >300m is better than anything I tried earlier and is far beyond what I'll ever care to use MP for. IMO getting a high output telemetry module is just a vampire sucking the energy and flight time from the copter. 

      If you buy an antenna for the 3DR radio, make sure it is the correct gender. The ones I bought needed an adapter.

      I'm using IBCrazy antennae for the 1.3 ghz video, but haven't really used it much; am in the process getting it working on the Spy 750. That guy really knows his stuff.

    • Felipe Rabat > DG May 3, 2015 at 12:28pm

      Yeah, I switched to IBCrazy antenas for video (and not the extremely high ones, either!) and I trippled my range.  Looking to do something similar with my MavLink...

    • DG > Felipe Rabat May 3, 2015 at 12:34pm

      I was amazed at how well the signal is with the current setup, especially since the Frsky rx dropped to 40 during the last flight. This was underneath a large tree and another 50 ft. tall pine tree further blocking the LOS.

      I have <$20 into these 915 antennae/adapters. The only other thing I did was re-load the firmware in the radios. Now I can't connect using Tower....if it isn't one thing it's another.

    • Felipe Rabat > DG May 3, 2015 at 12:54pm

      Well, I placed an order for a couple of these...  We'll see how they turn out.

  • Tom Boyd April 7, 2015 at 1:02pm

    I have a 3dr assembled Y6 I got last spring.  The FPV was not acceptable IMHO.  I tried new antennas, but after about a year I got soooo fed up with the FPV that I contacted a local custom drone company for help.  The kind of company that, builds them from the ground up and, until recently, didn't even offer a drone that was < $10K.

    They have improved things 1000%.  The main thing they did was reroute all the video/telemetry cables so that they were not near any noise makers (esc's etc.) on the drone.  There was also some hardware upgrading. 

    According the them, some of the stuff 3DR delivers are not the best quality (could be a simple matter of 3dr choosing to use a particular brand that is know to have a higher than normal failure rate).

    In fact, one of the areas they have moved into is offering the Iris+, but only after they had gone through it, moved what needed to be moved and upgraded the questionable stuff.

    So, my advice.  Look beyond the antennas.  I went down the same path you did, even tried the same antennas you had pictured and it turned out my problem went way beyond just antennas.

    • Felipe Rabat > Tom Boyd April 10, 2015 at 3:50pm

      Well, I pulled the trigger on some IBCrazy antennas...  Got the transmitter CP omni, one receiver CP Omni, and one receiver Helical.  Even if not optimal, it should give me more range in the video side of things.  Still got to figure out what to do regarding telemery...  Repositioning of the components did get me a bit more range, but not all that much.

    • Felipe Rabat > Felipe Rabat April 26, 2015 at 9:04pm

      I am happy to report that so far, results on the new antennas are promising!  I am still missing a SMA to RP-SMA converter, so I have not tried all 3 antenans at once.  So, I kept the 3DR transmitter antenna, and put the Helical and the Mad Mushroom in the receiver...  Got more than twice the range.  

      Today (after the flight) I pulled out the Tx antenna and replaced it with the IBCrazy Airscrew, and will use the 3DR receiver antenna instead (I am betting the Rx is depending more on the helical than the omni, so maybe I will get more range now).  But anyway, I was a good 305m out (checked with Mission Planner the distance!) without video being completely lost (the distance before was 129m, and I had completely lost video at this distance).  So more than double the range so far (without changing the Tx antenna; I expect more now that I did replace it!).

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