Why the need For an 2,4ghz RC uplink?

2015-05-02_001.jpgHi all,

I Have a plan to build my own handheld groundcontroll station and was thinking about the 2,4ghz rc side of things... With having  a 433mhz telemetry uplink is there any need for a Traditional RC link?

If my Thinking is correct the 3DR Solo uses the Telemetry signal for RC controll Too, Correct me if im wrong! If they can do it why cant we? I know mission planner has an option for a "joystick" but there is also a need for the rc link aswell, Maybe the code would have to be tweaked?

Just an idea at the minute but What I would like to do is have a android stick on a 7" HDMI monitor runing droidplanner with a joystick conected for RC. (something similar to my image, just diy)

What do you guys think?

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  • I think that one completely open source hardware and software solution could be based on the Wifibroadcast  project:



    It uses two Raspberry Pi (one ground one air) and a link with wifi cards in monitor mode to transmit video, bidirectional telemetry and RC control.

    It is also included in the maverick project:


    "Maverick is a system for creating, maintaining and controlling UAV Companion Computers."

    Wifibroadcast – Analog-like transmission of live video data
    Wifibroadcast is a project aimed at the live transmission of HD video (and other) data using wifi radios. One prominent use case is to transmit camer…
  • I am surprised that no one brought this up: https://www.foxtechfpv.com/cuav-hack-link-uav-digital-link-system.html

    My understanding is that it's based on the same system that the Solo uses. In fact, Jordy from mrobotics.io mentioned it in a blog post here: http://mrobotics.io/the-solo-link/

  • And I have to say that I'm not a fan of joysticks that I can't pinch.  Thumbs, IMHO, are not a precision instrument.

  • I'm surprised that a company like Futaba hasn't come up with a radio that uses wifi, an iOS or Android tablet as a user-interface, and has a video feed.  Hell, they sell a friggin' $3000 radio that does nothing more than their $1000 radio.

  • Some good point here! I think what i would like to do is keep it as simple as possible, Anyone should be able to buy the same parts and copy me. Im not really looking on over complicating things and just thought that maybe i could use the Telemetry for the RC side. That looks like its not the way to go.

    As for OPlink i have never used one bofore and would prefer using someting I know and trust, I am now thinking of staying with my FRsky system for the rc.

    So maybe design a new case for the taranis with a 7" touch monitor in the middle running droidplanner, Easycap usb tv dongle for video input, smal Eachine DVR and a realacc 5,8ghz VRX. Ill probably do the case as a 3d design and upload it to thingiverse and Shapeways. Anyone used shapeways before? Still thinking about what orientation to have the monitor, vertical or horizontal?

  • It's not just about the frequency.  Sure, 5.8 GHz is less crowded but 2.4 GHz inherently gives you better range and signal propagation through foliage.  IMHO, the elegance of the Solo design is that there is one RF link handling everything (one link to rule them all and in the darkness bind them).  It's proof that it can be done and can be done seamlessly.
    While I am a fan of DIY, I appreciate great design over MacGyver setups.  As Scotty once said, "The more they overthink the plumbing, the easier it is to stop up the drain."  Sometimes you just need to get the job done and you don't have time to mess around with a lot of equipment.

    I think that 3DR's Solo design is the happy medium between DJI's tight integration and open-source flexibility.  Hopefully, the gimbal and the iOS app will go open-source soon.

  • I don't know what problems you had with OPLink, but there have been some bad batches of OPLink clones that have shorted antenna connectors. Unfortunately, the hardware is all clone hardware at this point, but the firmware is still supported by the LibrePilot project.

    One current OPLink user has recorded ranges of over 8km using stock (100mW) hardware and running control + a full 56kbs telemetry link.

    I've been wanting to try LoRa, but LoRa is really designed for very low bit rates, I think you could get control information through a true LoRa link, but I don't think you can get full telemetry without switching back to FSK.

  • Combined telemetry and rc links are a compromise in terms of performance of course. TBH OPlink has not been a great performer for me and others and has not been developed for some time. I would not select it for a controller now. Dragonlink has the benefit of having, I believe, transparent 19k serial telemetry and a wide user base and very long range performance. It is not especially cheap. RFD900+ supposedly does the same but I have not seen so many users. I think both use capable 32 bit MCUs.

    There are some great 433 1W LORA modules now that do long range telemetry. A really robust inexpensive approach is to use a FrSky LR9 and a 1W Lora module for telemetry. Maybe 10k range with good antennas.

    This project is gaining momentum. It uses said LORA modules to do PPM and Telemetry. https://www.rcgroups.com/forums/showthread.php?2837542-QCZEK-LRS-DI...

    Also Jordi at M Robotics says he will have an improved Sololink for sale soon. That will do HD video, RC, and telemetry in open source hardware. Prob about a mile range.
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  • @Brian, i didnt realise that about OPLink. nice.

    I agree with your statement regarding RC over telemetry. definitely not a good way to do it.

  • The OPLink sends the RC signal inline with telemetry, and has since 2013 - well before TBS crossfire, dragonlink, and RFD900+ have been around. Longer than 3DR modems have been around for that matter.

    You really don't want to send control information over the normal telemetry link, especially passing through a PC and additional RF links. It adds too many points of potential failure, and additional latency and jitter.

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