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3+km HD FPV system using commodity hardware

Posted by befinitiv on May 6, 2015 at 12:43pm

Hi

Over the last couple of months I have been working on a project that might be of interest to you: https://befinitiv.wordpress.com/wifibroadcast-analog-like-transmission-of-live-video-data/

Basically it is a digital transmission of video data that mimics the (advantageous) properties of an analog link. Although I use cheap WIFI dongles this is not one of the many "I took a raspberry and transmitted my video over WIFI"-projects.

The difference is that I use the cards in injection mode. This allows to send and receive arbitrary WIFI packets. What advantages does this give?

- No association: A receiver always receives data as long as he is in range

- Unidirectional data flow: Normal WIFI uses acknowledgement frames and thus requires a two-way communication channel. Using my project gives the possibility to have an asymmetrical link (->different antenna types for RX and TX)

- Error tolerant: Normal WIFI throws away erroneous frames although they could have contained usable data. My project uses every data it gets.

For FPV usage this means:

- No stalling image feeds as with the other WIFI FPV projects

- No risk of disassociation (which equals to blindness)

- Graceful degradation of camera image instead of stalling (or worse: disassociation) when you are getting out of range

The project is still beta but already usable. On the TX and RX side you can use any linux machine you like. I use on both sides Raspberrys which works just fine. I also ported the whole stack to Android. If I have bystanders I just give them my tablet for joining the FPV fun :)

Using this system I was able to archive a range of 3km without any antenna tracking stuff. At that distance there was still enough power for some more km. But my line of sight was limited to 3km...

In the end, what does it cost? Not much. You just need:

2x Raspberry A+

2x 8€ wifi dongles

1x Raspberry camera

1x Some kind of cheap display

Happy to hear your thoughts/rebuild reports :)

See you,

befinitiv.

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Tags: fpv, linux, raspberry, wifi, wifibroadcast
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Replies

        • malkauns > Kendall Wells June 4, 2015 at 11:33am
          what latency improvement do you expect?
          • Kendall Wells > malkauns June 4, 2015 at 11:38am

            Realistically, with Mavlink, joystick and HD Video and camera functions...  around 100ms at 150mbps is attainable...I think, possibly, maybe

            • malkauns > Kendall Wells June 4, 2015 at 12:13pm

              Is this just a guess or has someone actually achieved this?  Also what is the form factor of the TX hardware?

  • Kendall Wells June 3, 2015 at 11:26am

    OK Paul,

    I looked at the swat link you sent...looked at the ground pi app and noticed that it requires $3.99 purchase to unlock it

    Right now,I use gstreamer.apk it works the same without the v4l2-ctl camera control built in... I can do that via SSH in terminal

    I do get the stream and UDP mavlink data on overlay as well

    • Kendall Wells > Kendall Wells June 3, 2015 at 7:27pm

      I downloaded, unzipped and imaged the AirPi from the posted SWAT build on 3 different 16gb micro SD cards (class10)

      none would boot...must be an issue with the bootloader in the recent builds

      Strange indeed

  • Tristan June 3, 2015 at 9:10am

    Hi, very interesting project, I ordered some CSL 300 MBits to try it out :)

    Anyone thought about improving the app using the QGroundControl HUD component ? 

    http://qgroundcontrol.org/mavlink/image_transmission_protocol

    It would great to display telemetry over this HUD :)

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