3+km HD FPV system using commodity hardware

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.

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

        • Half way there - just need a connector to hook it up. Also some of that RG402 semi flex cabling would be nice...3702791419?profile=original

          • Noice!! You can put some epoxy glue around the top middle part of the antenna where the elements join to protect it from bending and breaking when you crash. I love making these. So much cheaper than buying them. :)
    • Definitely need to get rid of that 2.4GHz that you are using for control.  The interference decreases the range significantly.

    • You should definitely increase the intra frame frequency (-g). Try 10 or below. I found 3 to be a good value - any artifacts are quickly removed. Also, try setting the intra refresh type (-if) parameter to cyclic or both.

      raspivid ... -g 3 -if both

      • In my experience a lower intra-frame frequency is better when flying at the edge of reception as although the image is garbled I can still get a sense of what I'm seeing.  A higher intra-frame frequency seems to cut out the whole picture more and it's more difficult to surmise what you're actually seeing although the picture may appear "cleaner".

      • Thanks Martin, I've changed the settings. I'll let you know how it goes. I quickly benchtested the video and when I first started it up it was lagging by a few seconds but it soon settles to around ~200ms after 30secs or so...

          • I changed to -g 10 and ended up with a lot less artifacts happening
          • With -g 10 a big delay built up. Up to about 5 secs after 5mins.
          • I tested without the quad's TX running and got a lot better range and quality so UHF will be a great addition
          • I also made a bi quad antenna but waiting on a connector (see below)
          • I will look too making a patch/directional antenna for the receiver
  • Been getting decent results using 2 CSL's and 1 TPLink for rx and 1 Alfa for tx.  Still running on 2.4GHz for now.  I was getting a lot of break ups before in the video but I made a couple of 2.4GHz omni bi-quad antennas and things improved a lot!  Thought I'd post a video:

    https://www.youtube.com/watch?v=AqZyPGgBl8I

    • Developer

      Great!  nice to see the video!  I've got a bunch of new antennas as well that I hope to try in the near-ish future.

  • Hi all, I've got the link working between 2 Pi's but it's not overly practical as I have a laptop with the latest Ubuntu and I don't have a screen to use in the field with the Pi.

    I've having trouble getting the streamgoing with gstreamer:

    jem@jem-N51Vf:~$ sudo ./rx -b 8 wlan2 | gst-launch-1.0 -v fdsrc ! h264parse ! avdec_h264 !  xvimagesink sync=false
    sudo: ./rx: command not found
    Setting pipeline to PAUSED ...
    Pipeline is PREROLLING ...
    ERROR: from element /GstPipeline:pipeline0/GstH264Parse:h264parse0: No valid frames found before end of stream
    Additional debug info:
    gstbaseparse.c(1155): gst_base_parse_sink_event_default (): /GstPipeline:pipeline0/GstH264Parse:h264parse0
    ERROR: pipeline doesn't want to preroll.
    Setting pipeline to NULL ...
    Freeing pipeline ...

    Any ideas? Cheers

This reply was deleted.

Activity

DIY Robocars via Twitter
RT @chr1sa: Donkeycar 4.4 released with tons of new features, including path learning (useful with GPS outdoors), better Web and Lidar supp…
Nov 27
DIY Robocars via Twitter
RT @NXP: We are already biting our nails in anticipation of the #NXPCupEMEA challenge! 😉 Did you know there are great cash prizes to be won…
Nov 24
DIY Robocars via Twitter
RT @gclue_akira: レースまであと3日。今回のコースは激ムズかも。あと一歩 #jetracer https://t.co/GKcEjImQ3t
Nov 24
DIY Robocars via Twitter
UC Berkeley's DIY robocar program https://roar.berkeley.edu/
Nov 24
DIY Robocars via Twitter
RT @chr1sa: The next @DIYRobocars autonomous car race at @circuitlaunch will be on Sat, Dec 10. Thrills, spills and a Brazilian BBQ. Fun…
Nov 24
DIY Robocars via Twitter
RT @arthiak_tc: Donkey car platform ... Still training uses behavioral cloning #TCXpo #diyrobocar @OttawaAVGroup https://t.co/PHBYwlFlnE
Nov 20
DIY Robocars via Twitter
RT @emurmur77: Points for style. @donkeycar racing in @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video. https://t.co/Y2hMyj1…
Nov 20
DIY Robocars via Twitter
RT @SmallpixelCar: Going to @diyrobocars race at @UCSDJacobs https://t.co/Rrf9vDJ8TJ
Nov 8
DIY Robocars via Twitter
RT @SmallpixelCar: Race @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video. https://t.co/kK686Hb9Ej
Nov 8
DIY Robocars via Twitter
RT @PiWarsRobotics: Presenting: the Hacky Racers Robotic Racing Series in collaboration with #PiWars. Find out more and register your inter…
Oct 23
DIY Robocars via Twitter
RT @Hacky_Racers: There will be three classes at this event: A4, A2, and Hacky Racer! A4 and A2 are based around UK paper sizing and existi…
Oct 23
DIY Robocars via Twitter
Oct 23
DIY Robocars via Twitter
Oct 19
DIY Robocars via Twitter
Oct 18
DIY Robocars via Twitter
RT @NeaveEng: Calling all UK based folks interested in @diyrobocars, @f1tenth, @donkey_car, and similar robot racing competitions! @hacky_r…
Oct 13
DIY Robocars via Twitter
RT @araffin2: 🏎️ After hours of video editing, I'm happy to share a best of my Twitch videos on learning to race with RL. 🏎️ Each part is…
Oct 13
More…