I want to stream video from a camera 640x480 frame of 8-bit approximately.
I don't want to use wi-fi. I capture the data, encode it, transmit the signal over RF and receive it. Decode the signal.
My goal is to make a quadcopter streaming live video over radio frequencies. How is this achievable?
I am in my final year of electrical engineering in telecommunication.
You state frame size and resolution per pixel but no refresh rate. Assuming one frame per second, the data rate is: -
640 x 480 x 8 bits per second = 2.4576Mbps.
There are no cheap off-the-shelf solutions for this (even at one frame per second). For instance Zigbee will work up to 250kbps. Nordic NRF24L01G is good for 2Mbps and you might get 20 metres at this bandwidth and operating frequency but remember it only produces an output power of 1mW.
The best option you have is to compress the data using something like MPEG methods - this could reduce your streaming data rate by a factor of ten and then you have a chance of getting something off the shelf.
Not the easiest thing to do I'm afraid. There are several Video over RF solutions available. The FPV community in the RC plane and quadcopter community sells several kits that will do this for you. None of them that I could find are very open, however.
It's really a question of the necessary bandwidth, which is restricted based on the frequencies regulated in your area, and the encoding scheme used for the video.
The Ham community has been transmitting video since near the dawn of television. There's two kinds of television transmission, SSTV(Slow Scan TV and FSAT(Fast Scan Amateur Television). You might be able to find some schematics online. Different places will sell transmitters and receivers. Try searchging google for fpv video, atv video, and fpv piloting. You'll turn up some stuff.
If you want to go digial, Analog Devices makes a few chips that might help you, such as the ADV212 video compressor. It goes for about $40 but as a student you might get away with sampling one. Unforunately, it's only available in BGA packages, so your fabrication won't be trivial - you'll need a multi-layer PCB and the ability to solder to it.
You might be best served by going analog. RGB to NTSC converters like the Motorola (now Freescale) MC1377 are widely avaiable. You can form a baseband from this signal using this scheme and then upconvert it with a mixer into the analog TV band. If you have an amateur radio license, there are frequencies set aside specifically for this purpose. Once you do this, you can view the video signal with a plain old tube TV tuned to the right station. As an added benefit, if you have a poor SNR the signal just gets fuzzy rather than completely blacking out without warning in a digital system.
EDIT: another thought on the digital front - you could probably do MPEG or other video compression on a Digital Signal Processor like the Analog Devices Blackfin. ADI already provides a software library for MPEG4. This should cut down your bandwidth requirement considerably.
