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36C3 Wifibroadcast Talk

December 30, 2019

I held a talk about Wifibroadcast at the 36C3 Chaos Communication Congress in Leipzig this year. If you are interested you can watch the recording of my talk here: https://media.ccc.de/v/36c3-10630-wifibroadcast

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6 Comments
  1. hello,
    if we want to replicate your research, what would be the github page to start from? I have googled a bit, but there are many clones/forks of your project, and I could not be sure which one would be the latest software. best regards, -C

    • Hey

      For my work the repository https://bitbucket.org/befi/rpi_wifibroadcast_image_builder/src/default/ is a good starting point. There you can see the scripts that assemble my Wifibroadcast image. The other forks are likely newer but to my knowledge they did not change fundamental things for the transmission. Their contributions are focused on increasing the surrounding functionality for the Drone application. Doing that they sometimes gave up strict modularization of components. One example that I saw was that the wifibroadcast tx program included code to read out a gamepad.

      Therefore, I’d say it depends on your application. If you just want to use it to fly around then the forks are likely better. If you intend to use it for another application my code might be the better choice since due to the very strict modularization it is easier to separate functionality.

      Please note that I do not have a complete overlook over all the forks. It is just what I saw while randomly surfing their repos.

    • Luke Shanks permalink

      Enjoyed the Talk!

      I would say openhd is leading the way in terms of patches and features. It takes alot of tweaking to avoid packetloss and collisions when you use it in a bidirectional way (video,telemetry down and control stream up) In particular the 8812au adapter support is outstanding now.

  2. Allan permalink

    Hi

    I was trying to replicate what you have done here https://befinitiv.wordpress.com/wifibroadcast-analog-like-transmission-of-live-video-data/wifibroadcast-fpv-manual-setup/ I’m using raspberry pi 4, 2.4GHz TP-LINK TL-WN722N V2, No brand dongle that uses Atheros AR9271 chipset, and raspberry pi camera v2.

    It took me a while before I was able to find a solution on enabling the monitor mode in the 2.4GHz TP-LINK TL-WN722N V2 (the V1 is no longer available to any nearby store or even online here in our country). After enabling the monitor mode I followed your steps thoroughly, the TX side works perfectly (using Atheros AR9271) and I’m seeing that it’s really broadcasting packets base on the logs from the terminal window. However, on the RX side, when I execute the command “sudo ./rx -b 8 -r 4 -f 1024 wlan0 | /opt/vc/src/hello_pi/hello_video/hello_video.bin”, there was no new window that supposedly popup for preview. All I have on my terminal window is “DLT IEEE802_11_RADIO ENCAP”.

    I’m doing this project for agricultural monitoring here in our province. I’m hoping that you could enlighten me in this regard.

    Than you!

    – Allan

    • hello allan. thanks for your interest in my project. unfortunately I do not have any experience with the version to of the dongle. i would recommend the first use wireshark on the receiver side. you should be able to see lots of packets coming in there. preferably you should do this with the stick that is already supported. if get no packages then there is a problem with your transmission side. if you do then you need to dig deeper into the receiving end. for debugging purposes it is also helpful to send some other data than video, for example simple text data is quite good. this allows you to remove gstreamer and video compression from the.

      using the webcam that’s also not a problem. you just need to alter the source command of the gstreamer Pipeline. in my first wifibroadcast post (title: true unidirectional …) you can find an example.

      • Allan permalink

        Thank you so much for noticing my comment, I was really crossing my fingers that you could have a minute to read my query.

        I will test the RX side tomorrow using Wireshark and see if there are any incoming packets. Also, I have ordered another unit of Atheros AR9271 USB Wi-Fi dongle if in case it’s causing the problem (fingers cross).

        I’ll definitely go check your post about the “true unidirectional”.

        Thank you again!

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