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-transmiss...
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 :)
Realistically, with Mavlink, joystick and HD Video and camera functions... around 100ms at 150mbps is attainable...I think, possibly, maybe
Thanks, I will
Now, I need to find a Debian,Ubuntu,gStreamer,firmware,network guru to do my bidding
Know any?, I'm hiring
Actually, if someone has these skills, has the time and want's to be involved... I'll supply the hardware, real US Benjamin's and willing to share the Intellectual Property...just PM me
"Befinitive" you available?
Is this just a guess or has someone actually achieved this? Also what is the form factor of the TX hardware?
Have you looked at Teradek's products? The latency should be pretty low. Probably cheaper and more reliable than trying to come up with your own solution.
No, I have not, do you have a link?
I just found them... the long range version on only rated at 1/2 mile
I need 50 miles and control besides nRT HD Video
I am not worried about the cost, within reason. I need reliability
So I have been playing around with this solution and got it to work in many different ways and systems (Odroid, Edison, BBB) but so far I am getting only about 50m distance. I have not checked in an open field, so I am wondering what ranges are you guys getting? I am using the TP Link WN722n dongles on two Odroids, and I am using the C920 camera to get the video.
Also I tried just using regular Wifi and I seem to be getting better results, less latency 150ms vs 200ms or more with befinitiv wifibroadcast, and I get a lot more pixelation or lost packets when using the wifibroadcast method than when using just regular UDP. Anyone have similar results?
For a 50 mile link you are going to need something a lot "stronger" than 2.4 GHz wifi.
4G would be the easiest solution. Some Teradek's products can stream over 3/4 G modems --> http://teradek.com/pages/bond
If you want a direct link you'll need an antenna tracker and sub-GHz frequencies. COFDM is the keyword here. For example --> http://vidovation.com/cofdm-wireless-video
I am using Ubiquiti Bullet 5M, it is 5Ghz @600mw on each end and it will hit 50 miles easy...been there got the Tshirt
What was your setup; antennas, line of sight, data rate, range?
I managed to replicate the broad cast wifi video two using the images provided by Tommy Larsen.
2x RPI (not RPI2s) + 1 x RPI camera
2x Alfa AWUS036NHA (2.4Ghz)
1x Black Pearl FPV Monitor(which accepts hdmi input from receiving RPi)
I measured the latency from "lense to screen" as 0.23 seconds (3:07.101 - 3:06.872 = 0.229 seconds) which is fine for my purposes. I'll do a ground range test tomorrow and probably write an ardupilot wiki page with a setup for beginners and then include links to befinitiv's blog).
Hmm, that latency is not very good. I've gotten 170 ms latency on my desk over 4G.