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-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 :)

See you,

befinitiv.

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How is it limited?  The 5514 is quad core and each core supports NEON so maybe encoding through x264 is possible.  How much are they?  I've emailed for prices.  If they're $350+ I don't see anyone buying them, surely they can't shoot themselves in the foot that badly.

Yes, here is more info on that topic:

http://yo3iiu.ro/blog/
http://www.qsl.net/kb9mwr/projects/wireless/modify.html

2487Mhz would possibly be a nice frequency. Still inside the ISM band, but 25Mhz away from standard wifi channels 1-11.

Depending on the price, I'd definitely be interested too, at least to try it.  Even putting the camera into a gopro size case such that it would be balanced in a gopro gimbal would be a great start.  The problem is that the raspberry csi only currently supports a single cmos camera, and that's not really good enough for decent quality video/photos.  It might do for FPV but not for AP or research, and the quality is limited to 1080p/30 and 5MP for stills.  But, I'd be very happy to proved wrong.

For the cable, I made a cable from a kit and posted the ebay link earlier back in the thread somewhere.  It's shielded, round, and as long as you want and I've had no interference problems with it.  It's a pain to make, although the ebay seller will make them for you for a bit extra (well worth it!  I spent a day and a half swearing and cursing with limited success).

I have a GW5100 board. This is the price figure -->

http://embeddedsoftwarestore.com/store/em/EMController?action=produ...

I would post the output of gst-inspect if I had access to the board. RPi's encoder has much more options. It's a limitation of the software not the hardware of the i.mx6 platform.

Interesting, that site has the 5510 at $193:

 http://embeddedsoftwarestore.com/store/em/EMController/Gateworks-Co...

Still pretty steep though..  

Rpi encoder will have more options as it has direct access to the camera so can control exposure, resolution etc.

Maybe it's better to look for a UVC/rtsp camera after all, and hook it up to a raspberry.

BTW, I have mentioned this before. The sensors for the RPi camera are not produced anymore. So there should be support for a hopefully higher megapixel sensor coming soon.

UVC/USB will definitely add some unwanted latency.

Isn't that just for Atheros chipsets?  Was hoping for something for Realtek chipsets in the Alfas on 2.3GHz.

Interesting, that site has the 5510 at $193:

 http://embeddedsoftwarestore.com/store/em/EMController/Gateworks-Co...

Still pretty steep though..  

Rpi encoder will have more options as it has direct access to the camera so can control exposure, resolution etc.

Maybe it's better to look for a UVC/rtsp camera after all, and hook it up to a raspberry.

Do I need to manually patch the kernel ? Or has this been done already?

"Optinally, you can also patch the kernel driver to set the output power of the card to a fixed level as describedhere. "

I am up to the part of "git clone https://github.com/raspberrypi/linux.git" but its on 1% and has taken 10 mins already!

Paul,

    It's not necessary but it helps if you want to get the TX to output at it's maximum power.  I've never actually successfully completed that step.  I hope the first person that does will put the resulting binary somewhere so the rest of us can just grab it and use it.

This could be an interesting wifi stick for wifibroadcast. Relatively small, two antenna connectors (inside the case), 2.4Gh/5Ghz support and Atheors AR7010/AR9280 chipset which works with the same ath9k_htc driver as the AR9721 sticks like the TPLink WN722N.

http://www.aliexpress.com/store/product/Newest-2-4G-5G-wireless-USB...

It seems to be the same as this one:

https://wikidevi.com/wiki/Panasonic_N5HBZ0000055

This camera also seems interesting, dual lens cam that puts out two MJPEG streams:

http://www.aliexpress.com/item/MJPEG-30fps-1-0megapixel-720p-hd-OV9...

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