Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Maltaeron on March 19, 2008, 10:26:13 PM
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What is the difference? I am using 38khz, and I here that is the standard for TV remotes as well.
Also, what is it about being a modulated signal?
I have a setup with an IR detector and LED, no ICs, what is the basic principal for communicating like this?
Thanks,
Confused Person
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buy an serial to ir encoder/decoder module to do it for you like this:
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010407 (http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010407)
It will be extremely difficult and ultimately far more expensive to do it yourself. Without it you would need a lot of additional circuits built.
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Here is a little explanation of how this IR receivers work http://www.societyofrobots.com/member_tutorials/node/102 (http://www.societyofrobots.com/member_tutorials/node/102) ( in the area a little different from communications, but I believe it will be clear). The basics: we modulate our bit samples with 40 KHz (or 38 KHz, it is relatively wide-band, so 40 KHz receiver will most likely sense 38 KHz signal). Something like that: we a re sending 10101 pattern
1 0 1 0 1
______________________ ______________________ ___________________
_______| |________________| |____________________| | _
and modulate IR LED intensity.
__ __ _ __ __ _ __ __ __ _ __ __ _ __ __ __ _ __ __ _ __
________| |_| |_| |_| |_| |_| |_| |___________________| |_| |_| |_| |_| |_| |_| |_______________________| |_| |_| |_| |_| |_| |_| |__
Receiver demodulate it into initial pattern (text is formatted automatically, really second and third "one" bits look loke the first one)
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You might find this handy:
http://www.societyofrobots.com/robotforum/index.php?topic=3460.0