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I'm trying to build a wireless communication system using LED and photodiode sensors. The communication distance is at most a few meters away, and the communication speed can be around 10kbps or even less. I try to use pre-built modules for sender and receiver systems as a turn-key system, but I found none so far.

  • Do you know where can I find some modules/kits or whatever that does the LED communication?
  • If there is none, is there any schematics or documents/books so that I can use to build one?
prosseek
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    Have you considered VLC (visible light communication)? Or maybe that's what you're talking about... Anyhow, you can find some example projects by Googling. Also, this https://electronics.stackexchange.com/questions/16626/what-solutions-if-any-are-there-for-visible-light-transmission-vlc – DigitalNinja Apr 14 '17 at 00:33
  • Am I the first one to think "IR remote control"?!? Arent there a couple *billion* of these devices in everyday use all over the planet? - I'm sure if you do any looking in that direction, you'll find plenty of television/vcr/stereo/whatever remote control LED & receiver pairs that should fit the parameters you've listed here. – Robherc KV5ROB Apr 14 '17 at 02:26
  • @RobhercKV5ROB - Since standard remote control use a 38 kHz carrier and msec pulse timing, they are not suited for 10 kbs transmission. Which is what the OP requested. – WhatRoughBeast Apr 14 '17 at 03:29
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    @WhatRoughBeast Well, he did say "or less"...it's less! ;) – Robherc KV5ROB Apr 14 '17 at 03:34

2 Answers2

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The major challenge with communicating with light is interference from the SUN or 60Hz room lighting or 80,000Hz electronic-ballast fluorescent lights.

Sending a coded optical tone ----- 38KHz ----- is the simple and robust method.

You can recovery these tones using NE567 tone decoder, which provides a logic output upon arrival of a "strong tone". You will need to DC_block the input signal.

http://www.x-robotics.com/downloads/pdfs/NE567_SE567_2.pdf

schematic

simulate this circuit – Schematic created using CircuitLab

The dual Rload, with Diode(s), allows high current operation at high photon fluxes.

analogsystemsrf
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You can get two USB Infrared Toys from Dangerous Prototypes. They use 38kHz demodulator at receiving side, which is pretty much a standard in infrared remotes. The device is open source and Python scriptable, so you will have a fun time hacking it for your application.

Volodymyr Smotesko
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