We have moved to a new Sailfish OS Forum. Please start new discussions there.

Transfer data with light?

asked 2014-02-14 22:18:17 +0200

vattuvarg gravatar image

updated 2015-11-05 21:56:37 +0200

Have a look at this TED talk by Harald Haas about wireless data from every light bulb.

I think that type of data transfer could be made with just the screen and the front camera. All it takes is an app to do it. The hardware is there.

Maybe there could be modes for different distances? A fast mode for the phone in the next seat on the bus. A slow mode for outdoor messaging? An emergency MayDay mode too, perhaps?

(This idea is called darkMess and is part of the Jolla Helm suggestion for the second device hardware thread. Also used in the sailfish car mode UI thread.)

Saw the Goccia activity tracker at Slashgear and it uses light to transfer data from the device.

One ways Goccia is able to last so long on a charge despite its small size is that it uses LED light sync technology. To synchronize data with the app on the iPhone or iPad, you need to place the Goccia on the front camera of the device and tap it to start synchronization.



My Nokia Blog has posted an article about a Windows Phone app called Over Here that cleverly uses light in a simple manner. Not much data is transmitted but enough of it.


We could have tried something similar at a concert last week, but thought about the flashlight too late. The flashlight would be strong enough even with full lights inside the arena.

Now for android too... http://www.engadget.com/2015/02/12/lookfor-flashing-lights/


Lifi can be received with an off-the-shelf solar panel.

edit retag flag offensive close delete


Promoting to skunkworks..

Stskeeps ( 2014-02-15 22:34:56 +0200 )edit

Jolla phone2 with Wysips Crystal + LiFi integrated, a must have, cream of cream thin layer transparent solar charger (allow reduce 20% battery size , self-sufficient + led communication.

So far better before other brand/device if exist on Jolla phone/SailfishOS http://www.youtube.com/watch?v=DFUCX6Wb5Lg

redge73 ( 2014-03-12 04:32:59 +0200 )edit

2 Answers

Sort by » oldest newest most voted

answered 2014-02-23 15:04:12 +0200

aironeousb gravatar image

updated 2014-02-23 16:25:54 +0200

I already suggested this be added to the other half E-ink display or to the front screen of the next Jolla phone along with wysips. Wysips is a transparent solar panel that gets sandwiched into your smartphone touch screen and is also capable of receiving LiFi when partenered with the oledcomm tech.

The tech is from http://sunpartnergroup.com/ and http://www.oledcomm.com/LiFi.html

They demonstrated LiFi on a phone at CES 2014 here http://on.aol.com/video/oledcomm-lifi-demo-at-ces-2014-518082294 as you can see they have a little receiver that you can plug into your headphone jack.

edit flag offensive delete publish link more



That LiFi sensor is smaller than I expected. Good. Might it be possible to combine this technology with a normal camera sensor to create an unlike light sensor unit?

vattuvarg ( 2014-02-23 15:21:31 +0200 )edit

Another good thing with LiFi is that it works even when the LEDs are dimmed down so much that the light isn't visible. In a car that would be perfect. There's already lights in the interior of the car. They could be LiFi beacons too. ...and no dangerous radiation, just light.

vattuvarg ( 2014-02-23 16:33:48 +0200 )edit

Wysips is a solar charging technology... A good backup charger. ...with LiFi. Yummy.

vattuvarg ( 2014-02-23 22:38:40 +0200 )edit

answered 2014-02-15 13:16:27 +0200

Henque19 gravatar image

A camera, as out eyes, captures light only a few times every second (~30 frames/s). So a camera capturing data from a modulated lightbulb means a data transfer rate of a whopping 30 bits/s... pretty useless unless analog data is transferred.

But a TOH with a photosensor could work. Then we are limited by the 400kbit/s of the I2C interface.

edit flag offensive delete publish link more



Sometimes even less than 30 bps can make a difference. Traditional telegraphy has a low transfer rate and still changed the world. You should also consider that the camera captures more than one pixel at a time. QR tags are already used for data transfer using light. What about adding the time to the two-dimensional bar codes by creating animations?

vattuvarg ( 2014-02-15 13:50:17 +0200 )edit

The darkMess flasher could be used for other things too. Airports already use barcodes as an example. The system could also be used to transfer secret messages by displaying photos with barcode overlays.

vattuvarg ( 2014-02-15 13:56:03 +0200 )edit

Yes, 30 b/s was huge >100 years ago, but not now. Having a time-dependant QR-code is cool I grant but requires a dedicated screen. The biggest (177x177pix) QR code holds ~20kbit, meaning we get 600kb/s but that requires clear line-of-sight. Wifi is capable of 1000 times higher transfer rates over longer dinstances.

Your applicatios are conceptually pretty cool, but very impractical IMHO.

Henque19 ( 2014-02-15 15:40:39 +0200 )edit

Hmm, isn't the proximity sensor a light sensor? What can it do?

00prometheus ( 2014-02-15 17:06:46 +0200 )edit

@Henque19 - The speed isn't impressive but the most used messaging system on this planet (sms) still has limits too. Speed isn't everything. Sometimes it is good to have a fallback system when everything else fails. People figured out a way to transfer money with just a SMS so maybe there are additional uses for optical messaging too. And compare the darkMess idea to the 802.11 family. the B standard has a longer range than the G standard. Signalling with light needs different versions too.

vattuvarg ( 2014-02-15 18:58:35 +0200 )edit
Login/Signup to Answer

Question tools



Asked: 2014-02-14 22:18:17 +0200

Seen: 1,636 times

Last updated: Nov 05 '15