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.
Replies
Not sure if people heard but the latest version of Tower supports displaying H264 video. Fredia is the Tower lead and we discussed this on the ardupilot dev call and we wondered if anyone here might be interested in trying to get it working with Wifi Broadcast?
This would be amazing, perhaps just include gstreamer support! This would add a whole umbrella of HD downlink support.
so new alfa 5GHz dongles are here. On the tx side everything works fine and I can inject packets. On the rx side I have no luck. I had wifibroadcast working a few months ago, but for some reason I decided to start with a fresh raspbian.. using either the ALFA AWUS051NH v2 adapters I get the error "DLT_IEEE802_11_RADIO Encap". This is on my pi as well as on my laptop. What could this be? If I create a wifi access point on the receiver and connect the copter pi to it I can stream video fine.
https://befinitiv.wordpress.com/2015/04/24/using-raspberry-as-a-dis...
This might help?
What tx/rx parameters are you using at either end?
Screw 5.8ghz and go for 2.3ghz. Working wonders for me after I hacked the atheros drivers. Better penetration too. :)
But what if I want to use Taranis plus with L9R receiver which is 2.4 GHz?!
thanks guys for the info. Getting the AWUS036AC to work looks a bit involved... so I think I will order the AWUS051NH v2, as you report that it works...
has anyone tried these? Alfa Network AWUS036AC Long-Range Dual-Band AC1200 Wireless USB 3.0 Wi-Fi Adapter w/2x 5dBi Removable External Antennas for Extreme Distance Connections - 2.4GHz 300Mbps / 5Ghz 867Mbps £28. Maybe worth a try for 5.8GHz? I haven't had much luck with the cheap CSL adapters. Felt promising initially and they work using wifibroadcast but the injection rate is very low compared to the WN722N. I'm still keen, though, to get it working on 5.8GHz. This avoids me having to dig through openlrsng again (it certainly works but it is an additional pain to set up comapred to taranis 'plug and play' RX and TX). But the main reason is to be able to fly with a couple of 2.4GHz TX people around. 2.4GHz for video is not so useful then.
Hallo Tobias, here are two links for raspberry drivers for the awus036ac:
https://www.raspberrypi.org/forums/viewtopic.php?f=66&t=66499&a...
https://www.raspberrypi.org/forums/viewtopic.php?p=706261
Have not tried myself and also don't know if packet injection works