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
I am a aircraft engineer, I can build good fixed wing drones and configure APM into them. I am very weak in IP communication software. is it possible to buy preconfigured raspberry pi for this HD link. so that all one has to do is to fit recomnmended wifi dongle and start flying. just a question.
Maybe I could prepare SD card images. All you would have to do is to write them onto a card and then everything should work. Seems like a good idea.
That is definitely a great idea ! Your audience will largely expand to people (like me) not familiar with Linux world and any idea to make our life easier is more than welcome.
And it has just got even cheaper thanks to a drop in the price of the RPi! But even so I would love to see if the newer Pi makes much of a difference.
New to this all but I'm assuming you can use a 5.8ghz wifi setup for this? I run 2.4 as my transmitter for my quad and didn't want interference from the system.
The project depends on some features (namely good monitor mode support) that are not well supported on many cards. I had to buy several different card types until I found a good one for 2.4GHz. Currently, there are people doing the same for 5.8GHz but they have not yet reported back any results. But I'm optimistic :)
I saw Alfa make a 5.8ghz version, I'm a noob and going to make the dangerous assumption that it will also work? If only the AUD hadn't dropped so much I wouldn't mind wasting money on a 5.8 version haha
I hear that mate....I wish I got into this hobby a couple of years ago! Would have been a lot cheaper...hopefully one of the other guys are testing 5.8Ghz out.
On a side note, beinfinitiv do you think a cloverleaf antenna is the go for TX side?
Sorry, I have no deep RF expertise. I use a simple dipole on TX. If wifi would work with circular polarization I don't know.
It works :)
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