I am currently studying Aerospace Engineering at the University of Manchester, England,
UK. One of my final year projects is to implement and integrate the communication systems onboard a rotary wing UAV (tumbleweed if you want to google it) (2kg payload on a 18kg structure). My main requirement is to send HD video with a minimum bit rate of 20Mbit/s as well as other information for flying the vehicle and information from other sensors e.g. IR imagery. Would this mean that the connection would have to operate for this 20Mbit/s, because that leaves 802.11. or is there a better method for sending HD Video? What other communications do i need to consider? And what are the other main components that are generic to each UAV? i am at the beginning of the project so any information would be great.

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i dont think any modem will be able to suite your needs. you would need to compress the video onboard.....etc. use a HD digital camcorder with a video out, and send a lower quality video to the ground by wireless video. you will have the HD video recorded on the camera when you land.
I've not been able to locate an HD transmitter that would be sufficient for our uses yet. Professional sportscasts use wireless HD but these run in the $6,000 range and that's just the 150' transmitter! Its also

Belkin has is $500 gadget that's far too large.

The Axis Camera looks interesting as it is already in H264 and on IP. I've used SD Axis products fro years and while the quality if good, there might be too much latency for use in a UAV. At $1600 its probably the closest.

Post if you find anything that does fit the bill (by which I mean capable, lightweight and cheap!) . In the meantime do what I've done and Michael recommends - record onboard in HD and transmit the the downlink in SD.

Paul
There are also stand alone encoders available from AXIS (M7001) which start at around $350 (without camera).
This encoder is can deliver two simultaneous video streams; one in M.264 and the other in Motion JPEG, at full frame rate and in all resolutions up to 720x480 NTSC. It is also extremely small & lightweight (1.5" x 1.2" x 4" at 82g) with BNC connector at one end so you can attach your own camera. Can also be ordered as a Surveillance Kit which includes a mini camera.

Check out: http://www.axis.com/products/cam_m7001/index.htm

Marc
The elphel camera is open source, cheaper than the Axis stuff, has several compression schemes, can stream via WiFi to an open web client they provide, and is capable of capturing 30fps at 1920x1088. Up to 8 SD cards can be used for offline storage too. If you use this, just be sure to post your results back - since I am interested in using this system too : )
Still working on my flight assembly before I focus on video
One of the Lunar X prize teams is using it as their video platform
The linuxdevices articles and wiki are really good for understanding the system
Since you're working in academia and doing this as a project, it can be really helpful to have access to the underlying source too
ian
There is a version of the camera with with the extension board (http://wiki.elphel.com/index.php?title=10369) that allows to connect external SATA HDD (or SDD that is more appropriate to UAV) . With compass/GPS attached (http://www3.elphel.com/nc353_369_geo) each video frame has the Exif geo-code data
Wow, I'm guessing you're the same Andrey that started the elphel project - I didn't realize you were on the diydrones forums. I've enjoyed reading about your system - and have thought the elphel cameras would be ideal for video on various autonomous flying platforms. The only outstanding question I've had is: which processor are you moving to since it seems the Axis core you use is going away?
Since I will have the GPS also being read by my microcontroller, I assume it would be fine to split the signal into the elphel, and maybe also insert camera position information (tilt, etc.) into the EXIF?
Ian, that's me, correct. I never posted on this forum before - just watching our access-log, this is how I found out about diydrones.

Processor? It will be TI DaVinci. Splitting signal - it probably is possible with some coding, currently GPS and compass data are just handled by the camera processor, stored with each frame and then encoded into Exif of each frame. The data is also available to PHP through the PHP extension or as XML file (like here - http://camera4.elphel.com:8081/meta , but that camera does not have any of the compass/GPS attached).
Thanks for all the advice, as it would be difficult to transmit for the required distance(2km), I had to go back to the customer and change the requirements slightly.
-20kg with 2kg payload, of which we need a HD camera, IR camera, and other instruments aswell as autopilot
-instead of streaming full HD can send reduced framerate e.g. 5 fps of HD video

-i have decided upon
-Three communication systems onboard
TR423-1 – 250mW Wireless Digital Link
400MHz
giving 5.4Km line of sight
For Telemetry and control
Would require relay drone

35MHz FM transmitter
To kill UAV in emergency
42x27.1x13.4mm
13g

IP922-OEM 100mW-1000mW – 1.9Mbit/s
902 - 928 MHz
For HD video communication
Reduce the number of frames limited by bandwidth
Giving a required bandwidth of 1.8Mbit/s.
126.5mm x 88.9mm x 22.1mm
142g

would these be ok and would they integrate? i have a PDR on thursday and feel under prepared so any help would be great.
Dear Sir,

Hello , I have to ask you about the price of IP922-OEM, how much is it ?

Best Regards,
Amir .
Er that will be well outside of UK regs from Nov both in weight and distance requirements. Or does the university have a way around that?? See here
I'm trying to get my auth to operate sorted with the CAA right now. I dont think they have thought that far though. Anything above 7KG and it will be harder still, your airframe will have to be LMA certifiable at very least.

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