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.

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Replies

    • Looks good.

      • wtf, I didn't write that..  this forum software must have been written in the 90s, it's really getting embarassing now..

        Anyway, I was trying to say I can' t see any reports of successful packet injection for the awus036ac and doesn't look like the chipset driver has made it into the kernel tree yet.  AWUS051NHv2 works great for me over 5ghz.

  • The raspberry pi compute module dev kits are on offer for £46.19  at RS http://uk.rs-online.com/web/p/processor-microcontroller-development... also the compute modules are now £19.50

    Might be cheap enough to consider now ?

    • Do mean for a normal wifibroadcast setup or 3D? Because you only need a raspberry pi A+ for tx and RX which is much cheaper than a compute setup
  • I wonder if its possible to reduce latency by over clocking the tx raspi GPU or its core? Does anyone have any thoughts on this?
    • OCing won't probably change the latency by an observable amount.

  • hi,

    have somebody experience with the new gateworks gw5510 http://www.gateworks.com/product/item/ventana-gw5510-single-board-c...

    they offer also an dual band(2,4 ghz and 5 ghz) Mini PCIe wifi card. http://marketing.gateworks.com/acton/attachment/2923/f-00c1/0/-/-/-... . based on the Atheros XB116 reference design.

    because the hdmi input and less weight, only 1 oz (28g) it looks super to use them as tx module. maybe cool to transmit hdmi signals directly from gopro ore all other cameras with hdmi output.

    the gw5510 can run openwrt https://openwrt.org. think it must be possible to get wifi-broadcast working on it.

    /g

    wolke

    • The GW5510 has already been discussed here some months ago.

      I have experience with GW5100, but it also applies to GW5510. The hardware is great, but the software is not that great. It won't have any multimedia capabilities if you run OpenWRT on it. At the moment you must run Yocto to do hardware encoding/decoding. The encoder is very limited on the software side - you can basically only set the bitrate, resolution and a few other options. It's more like a demo than a real encoder.

      Maybe things hae changed in the few months I have not looked at the software.

      • Hi. I looked at the spec sheet for the GW5100 and see that it has some analog inputs. I didn't look too much into it, but I would think that the driver would have some user configs that would all you to change hue/saturation/brightness etc via v4l2-ctl.

        I'm curious, what things do you want from the encoder that isn't already provided? Maybe the analog in driver they're using doesn't have these user hooks, in which case (yay opensource), we can always add them in ourselves. I'm very interested in a GW5510 for more than just video streaming, but I would have to see how developed their input drivers are (and really the feature list of their input capture device) for HDMI. I saw a price around here that the GW5510 is about $180 - $190, in which case I would attempt to buy it so I can mess around with the input stuff. For that price with full industrial parts on it, I think it's perfect for me. Everyone here wants a rpi, but really I think a more specialized board fits the bill *much* better.

        Also, I'd run Yocto instead of OpenWrt. I just looked at their Yocto offerings and it seems like it has somewhat better wireless performance anyways.

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