Li-Fi transceiver

Hi Techoman
A very interesting read thanks for sharing
I hope you do proceede with it and keep us all informed
The authours results to the expected theretical results are very impresssive
regards
john
 
This research paper is full of explanations of very basic electronic stuff, but is short on something as significant as how different levels of ambient light affect the transmissions. And then there's the simple electronics used in the research.

As I viewed the "video" samples of transmitted and received screens, they do look way too identical except for some shift in the capture.

My simple experiments with light transmissions have always been fraught with noise and interference unless I conduct them in complete darkness in some kind of enclosure. I can't imagine and experimental gadget transmitting from a TED stage.
 
Some years ago stereo audio light tests were made over long paths in clear condions: http://www.maxmcarter.com/lasrstuf/laserexperiments.html

There was also an attempt at local in city computer light link over about 1/2 mile [decades ago]- trouble with fog and dust and birds reported. It's certainly a different method requiring accurate high gain narrow beam transmitters and receivers... seems to work great when light beam confined to skinny fibers... ;-0 [attached local modified sign...]
 

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Whst range intended ? What local air clarity? This field has been much explored for voice comms - thus Bell's Photophone (1870s) & the amazing 1930-40s German Lichtsprechgerät 80 (Carl Zeiss) that had clear air ranges of several km! Refer

Lasers are now the obvious light source BUT serious issues with "devious beams" abound. Best perhaps hence to initially consider invisible IR,especially since PICAXEs have inbuilt IR data commands.
 
I am not entirely convinced Li-Fi isn't anything more than an 'April 1st' concept. It's not impossible to use light as a medium; IR proves one can, but I don't see how one can actually provide a signalling visible light signal in all circumstances, have a receiver reliably determine that, and do it both ways.
 
Maybe I'm just overly sceptical but when I see things like "IrDA - Same principle as VLC but uses infrared light instead of visible light", when I know IrDA works in a different way to what they appear to be describing, I get rather suspicious.

One can flash a torch at someone and communicate over large distances; Navies and others have been doing that for years, but to do that from a light bulb, LED or not, without observers perceiving changes in light intensities, or being able to detect microsecond long colour shifts with mobile phone cameras in supermarkets, with data rates as high as claimed; I'm not convinced.

I am sure VLC does work. But I am not convinced it works as well as is being hyped. There are some links and references in that article so I will take a look at those later.
 
That's a useful collation of papers. The EnLighting paper goes a fair way in describing linking bulbs together and describes something I would have anticipated to be achievable; 400 bits per second transmission.

But that's a long way off the megabits per second some are suggesting are attainable. I can appreciate it's 'early days' but there seems fundamental and impossible hurdles to overcome to get to where some say we already are.

Like how it works in the dark when one doesn't want to turn lights on.

It's definitely something worth getting involved in, even if just to discover what the practical limitations are, to see how easy or not it is. So please don't get me wrong in that respect. I'd love to see it work as well as 'the hype would have it'; I am just struggling to see how it can. I don't mind being proven wrong.
 
Although I can envision point to point communication, but to achieve sufficient signal to noise in a omnidirectional system (like WIFI) you may have to flood the room with light (visible or invisible).
Using IR will suffer greatly from heat sources in a typical environment (electronics, candles, cooking etc..)
Using UV will significantly increase skin cancer.
Visible light.....yeah only when people are outside the room.
Maybe you can "hide" LiFi signals in the picture you view on your TV screen .....
 
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