I've researched LiFi before, but everytime I research it I find expensive commercial equipment, or hobbyists playing with very low data rates on Arduino.
I have many questions, especially how a LiFi receiver works. wouldn't this essentially need to be a high speed camera with very few pixels?
Does anyone have recommendations of a dev kit, or transceivers to play with this? Also, ones that don't cost several thousand dollars?
The technology is mostly in those two camps because it's new, expensive, and niche, like WiFi was 20 years ago. As production increases (starts?), components will drop in cost and become standardized and more ubiquitious. At the moment there is a lot of practical research you can read about from conferences like OFC [1] and SPIE PW at the free-space laser or telecom tracks [2]. At the moment transmitters and receivers are made up of highly specified components for their use case and are very parametrized, for example there are hundreds of different DFB lasers that can be used as sources.
I'm a little surprised that IEEE has already standardized, especially given the wavelength they chose but I imagine their members were forced to adopt a prolific technology as without a standard they risk the technology moving ahead without them.
Basically, the only new principle involved is that instead of de-serialized and subcarrier modulated data modulated onto 2.4GHz sinewave and emitted from antennae as electrical field changes, it is now sent as changes in light level on subcarrier frequency.
Or more simply, maybe it could be done in YouTuber style by a light-emitting diode on Tx antenna port and a photo-sensitive diode on Rx antenna port? Switching speed of Tx side LED could become the limiting factor in that case.
> wouldn't this essentially need to be a high speed camera with very few pixels?
A camera sensor 'pixel' is just a device which conducts proportional to the amount of photons that hit it. A typical digital color camera uses CMOS chips to do this, with a filter on top of them to isolate red, green, and blue. It is pretty basic; the real trick is getting millions of them on a 1/4" sensor and having them relay the data properly with a reasonable amount of noise.
We have other devices that are "just a device which conducts proportional to the amount of photons that hit it" but we do not call all of them "cameras".
A camera is a device which receives light signals and translates those into an image of some format.
A photovoltaic cell in a solar panel is a device which generates electricity proportional to the number of photons that hit it.
A photoresistor is a device which resists current in proportion to the number of photons which hit it.
See now, such a LiFi transceiver would not necessarily be termed a "camera" any more than the infrared sensor in urinals is a camera. I believe that's the way we want it to be, right? LiFi has no use for producing images, only translating light back into network and signaling data. That's not called a "camera" by any means.
> We have other devices that are "just a device which conducts proportional to the amount of photons that hit it" but we do not call all of them "cameras".
But if you took those devices and made an array of them you can make a camera sensor. Ergo, if you take one element of a camera sensor you have a light detector element.
You want to call it a "camera sensor" but I personally would not attach the moniker "camera" unless they are in the business of translating light into images of some kind. Here, let's ask Wikipedia:
"A camera is an optical instrument used to capture and store images or videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film."
See now, a camera is the whole instrument, not merely its image sensor. But a camera uses an "image sensor". What is an image sensor?
"An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information."
So there is no way we've described what's going on in LiFi. For example, you walk up to a urinal and the infrared sensor detects you. Does it paint an image of your privates on a website? No. There is no camera in the urinal, hopefully. The urinal is only interested in whether you are standing right there or if you've left. The urinal does not employ an "image sensor", it uses something dumber.
Likewise, do your solar panels use cameras? They conduct based on exposure to light, don't they? But what is a solar panel concerned about? It generates electricity, not images. A photovoltaic cell is not an image sensor because it has nothing to do with images.
What would your camera be if I disabled the viewfinder display and eliminated its ability to save files on sdcard? Would it still be a camera if its sensors produced electricity but it couldn't provide me an image based on that conduction?
LiFi is not using something dumber, but LiFi is likewise unconcerned about creating images. Since a camera is, by definition, concerned with images, LiFi does not use cameras.
I think you would benefit from this advice as well; and I did attempt to apply logic, but you're ignoring the quoted Wikipedia definitions, and essentially we're just talking past each other, and I have no idea what sort of terminology you're trying to throw around now because it doesn't evidently have anything to do with LiFi tooling as it is.
I answered a simple question: 'is this essentially a camera with few pixels', and I defined what a camera pixel is and agreed that it is 'essentially a camera with few pixels'. It obviously isn't a camera, just like a bicycle is not a motorcycle, but it is 'essentially a motorcycle with a person as an engine'.
If you still think that is wrong, then that's fine I guess; it's your opinion and you are welcome to it.
I appreciate the agreeable answer, but it's also worth noting that the bicycle came first in its simplicity, and so the correct framing is that a motorcycle is a bicycle with an internal combustion human.
So how did cameras start? Well, the word is literally Latin for "room" because a man would go into a small, darkened room with only a pinhole opening at one end, and he could observe an image projected on the far wall.
So the original "camera obscura" had no lens or sensors at all! It was essentially a refractive element and a screen. The observer could then paint or draw according to the projected image he perceived with the image sensors in his eyes.
I have many questions, especially how a LiFi receiver works. wouldn't this essentially need to be a high speed camera with very few pixels?
Does anyone have recommendations of a dev kit, or transceivers to play with this? Also, ones that don't cost several thousand dollars?