more snake oil, LED Wi-Fi - Page 1
Forum section: electronics / general

author: Moshly
author_rank: Regular Contributor
timestamp: November 25, 2015, 07:16:01 am
content: Hi, guysI just found this ->http://www.smh.com.au/technology/technology-news/move-aside-wifi-theres-a-new-superfast-wireless-internet-coming-called-lifi-20151125-gl7j79.htmlI don't see how it can replace Wi-Fi when its only one wayThe more i think about it, the more 'issues' i think it will have.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 25, 2015, 07:49:32 am
content: Optical communication is nothing new. Back in the days, some amateurs found a way to run Ethernet using laser pointers.Now, they're looking to use LEDs which don't need the precise aim needed with lasers.

author: timb
author_rank: Super Contributor
timestamp: November 25, 2015, 08:16:14 am
content: Quote from: Moshly on November 25, 2015, 07:16:01 amHow is it only one way? There's no reason you couldn't put a small IR strip on the back of a laptop or around the screen trim to transmit.Anyway, even if it is one way, that's still not a huge deal as the majority of network traffic is in one direction in situations where this type of speed would be useful. Downloading large files from a file server, remote access, etc. You would just use WiFi to initiate the request.The idea is to essentially have LiFi transceivers embedded in common LED bulbs and have the signal propagate through an entire office, for example.Easier than running gigabit Ethernet to each cubicle and without the associated security risk of WiFi (since light can't penetrate through walls like radio waves can, it could be used in secure areas).It's not snake oil. I don't think that term means what you think it means.Sent from my Tablet

author: bktemp
author_rank: Super Contributor
timestamp: November 25, 2015, 09:01:23 am
content: What is the frequency response of a white led?I doubt a white led can be modulated at anywhere near 1Gbit/s. Using IR LEDs or lasers this is not a big problem, but white leds have a phosphor in front of a blue led and this significantly limits the response time. So this does not work.Maybe they could use RGB leds to get visible white light and use each colour for its own data stream. So you can get almost 3 times the bandwith using the same bitrate.

author: DimitriP
author_rank: Super Contributor
timestamp: November 25, 2015, 09:24:52 am
content: Quote from: NiHaoMike on November 25, 2015, 07:49:32 amShhhh....it's a "new" invention.

author: CaptCrash
author_rank: Regular Contributor
timestamp: November 25, 2015, 10:07:44 am
content: I listened to a report on this 12 months ago on the Science show pod casthttp://www.abc.net.au/radionational/programs/scienceshow/li-fi3a--the-led-based-alternative-to-household-wi-fi/5029298, talking to the scientists responsible within CSIRO. I think it was the same or similar group who developed WIFI who have come out with the technology.Its quite real and is no way snake oil.The approach was to use light as the broadcast medium from the network and traditional WIFI as the return path.At the time in the lab they were talking of transmissions in the multi gigabit ranges (2-3Gb/s) and I think several 10's of Gb/s with development (but thats possibly wrong) depending on frequency etc.

author: tooki
author_rank: Super Contributor
timestamp: November 25, 2015, 10:28:20 am
content: How quickly we forget. IrDA was a resounding success. It was everywhere, in offices and homes, for easy, ubiquitous Internet access for our Palm Pilots, PowerBooks and even the first iMac. Right? Oh, wait... Yeah all those gadgets had the transceivers and not a damned soul ever used it*. No wonder we relegated it to the circular file of time. (Never mind the youngsters writing for tech publications today as unpaid "interns" for no pay, who were toddlers when IrDA made its exit from the stage.)*OK that's not 100% true. Back in 2000, I had a PowerBook (the model commonly called by its code name, Pismo) and a Palm IIIe, and when traveling, I actually did use IrDA to sync them, saving me from having to bring the Palm cradle. (The travel cable was an expensive accessory.) IrDA was much slower than the cradle, but it was free and weighed nothing! But I'm a nerd, and I literally knew of nobody else ever having done this, even in years of doing tech support during the days when Palm handhelds were ubiquitous.Anyway, I'm sure this new optical networking can work just fine. It doesn't even necessarily need two wavelengths to get half-duplex bidirectional communication, since it's possible to multiplex, just as Wi-Fi does. (Of course, full-duplex does require two different wavelengths.) But I wonder what real problem it solves, and how well it performs in real situations where you have many devices, sources of interference, not to mention how easy it would be to block the transceiver inadvertently.

author: tooki
author_rank: Super Contributor
timestamp: November 25, 2015, 10:36:41 am
content: Quote from: NiHaoMike on November 25, 2015, 07:49:32 amAmateurs? They're commercial products. Canon used to sell them as "Canobeam". They call it free space optics. They're used in cities where a company has two buildings within sight of each other (e.g. across the street) and the phone company wants too much money for a leased line between them (or both buildings are too far from the shared central office, despite being next to each other). In the rain you could see the green laser beam.

author: Zero999
author_rank: Super Contributor
timestamp: November 25, 2015, 01:09:11 pm
content: Quote from: bktemp on November 25, 2015, 09:01:23 amAdd blue filters to the receivers and the response time of the phosphor will no longer be a problem.

author: madires
author_rank: Super Contributor
timestamp: November 25, 2015, 02:01:58 pm
content: Nothing new, just a copycat. Some researchers hit 1Gbit/s and more via a LED a few years ago:-http://www.bbc.com/news/technology-24711935-http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6249713-ftp://ftp.hhi.fraunhofer.de/jungnickel/OFC2014/Jungnickel_OFC_March2014.pdf

author: Halcyon
author_rank: Unknown
timestamp: November 25, 2015, 02:15:22 pm
content: So called "Li-Fi" has been around for a while now but not as a commercial product. Its applications are certainly interesting and could be incorporated into normal light fixtures (no one says it has to be in the visible light spectrum).Point-to-Point networking using lasers has been around for many years. This is just an adaptation of that.Hardly snake oil at all.

author: cloudscapes
author_rank: Regular Contributor
timestamp: November 25, 2015, 02:31:41 pm
content: "the LED light flicks on and off at such extreme speeds that it can be used to write and transmit things in binary code"That's weirdly written.News flash, LED flicking at extreme slow speeds can transmit things as well.

author: SL4P
author_rank: Super Contributor
timestamp: November 25, 2015, 09:13:18 pm
content: I recall about 10-15 years ago, they were exploring / using modulated fluorescent lighting to 'broadcast' pricing updates to miniature, low-cost, shelf mounted LCD displays on supermarket shelves...I wonder when that'll resurface? The LCD pricing that is...

author: FireFlower
author_rank: Regular Contributor
timestamp: November 25, 2015, 09:24:54 pm
content: I think there was a master thesis released where new wireless communications do not anymore need own transmit and receive frequencies or times. You just send stuff in same channel and receive on same channel without dividing transmit times. There is not patent for it so you could expect that come mainstream wireless technology because frequencies used for commercial purposes are expensive and when you need only one then it saves a lot money but you still have same speed. Basically half-duplex becomes full-duplex.https://aaltodoc.aalto.fi/handle/123456789/13428

author: timb
author_rank: Super Contributor
timestamp: November 26, 2015, 12:12:44 am
content: Quote from: SL4P on November 25, 2015, 09:13:18 pmIt already has! I've seen it in some department stores in the US. It's a small LCD that runs on a coin cell and uses BTLE to receive updates.Newer ones can also act as iBacons. The idea being you download an app on your phone which contains a map. The phone uses the BTLE advertisements from the beacons to triangulate your location. You can use this to navigate the store or find specific items. You can even check stock of an item in some cases! (Say you find a pair of shoes you like, you open the app and it knows you're standing in front of said shoes, so it shows you info about them, other colors and current coupons; then you select your size and it connects to a backend inventory database over the Internet to see if they're in stock at that store; if not you can have them delivered.)The down side is that iBeacons are a two way street. Even if you don't have the app open, if you've used it at least once they can now link your phone's unique BT ID to you, which means they can collect metrics on how long you look at a particular item, what you look at, etc.Even if you've never used the app, your phone will still respond to the beacon's advertisements, which means they can still get that data, just without tying it to a specific person. The only way to stop it is turn Bluetooth off.Sent from my Tablet

author: tooki
author_rank: Super Contributor
timestamp: November 26, 2015, 01:32:20 am
content: Mmmm, iBacon!

author: Synthetase
author_rank: Regular Contributor
timestamp: November 26, 2015, 08:36:13 am
content: Quote from: SL4P on November 25, 2015, 09:13:18 pmSeveral Richies supermarkets in Victoria have been using LCD price displays for years.

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 26, 2015, 12:07:28 pm
content: Quote from: Synthetase on November 26, 2015, 08:36:13 amSeen it in NSW as well, not sure which supermarket it was (I think it was a Franklins, but apparently they're defunct)

author: McBryce
author_rank: Super Contributor
timestamp: November 26, 2015, 12:42:40 pm
content: Quote from: tooki on November 26, 2015, 01:32:20 amYes, it's like normal bacon, just more expensive and leaves out several things that all other bacon eaters expect as standardThose LCD price signs are used in several shops around Europe.McBryce.

author: timb
author_rank: Super Contributor
timestamp: November 26, 2015, 07:48:17 pm
content: Quote from: McBryce on November 26, 2015, 12:42:40 pmBut, it's 70% lighter than regular bacon and tastier, too!Sent from my Tablet

author: tooki
author_rank: Super Contributor
timestamp: November 27, 2015, 01:15:47 pm
content: And doesn't cause digestive distress in most eaters!

author: GreyWoolfe
author_rank: Unknown
timestamp: November 27, 2015, 01:48:11 pm
content: Where is the iEggs to go with it?