frequency of IR reciever

Discussion in 'Embedded Systems and Microcontrollers' started by bhuvanesh, Jan 16, 2014.

  1. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
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    i am working on arduino.My remote control works on 40khz and it send 12 bit of information.So does 40khz mean i can send (approx)40000 bit per second,am i right or wrong.Thank you in advance
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    No. It takes many cycles of 40kHz to send just one bit of information.
     
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  3. ActivePower

    Member

    Mar 15, 2012
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    40 kHz is NOT the speed of information transfer. It is just the frequency at which your channel operates. Your actual speed would be way less.
     
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  4. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
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    yes,we modulating the signal.Right.i have an obscure vision on mudulation ever since i heard that term.Actually,instead of on IR light for certain time to indicate one.we are on and off the IR light.MY question is for ON it should blink for 600us means,how many clyces on and off ,does it take for 38khz .does it take completely 38 cyles for one on and off.please explain me.Thank you
     
  5. MikeML

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  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Many remotes send a 0.8mS pulse for a 0 bit and a 1.5mS pulse for a 1 bit etc. Each of those pulses is made from a 38kHz signal.

    There are some good internet sites showing "IR remote protocols" if you want to have a google.
     
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  7. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
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    sony sirc protocol.
     
  8. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
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    what i mean is in that 1.2ms how many cycles of 38khz passed 0.1/38khz gives a time in which one complete cycle.so for 1.2 ms *num of cyles in 0.1 ms gives the number of cycles in 1.2.thats my doubt.its not something related to protocol.its about modulation
     
  9. MikeML

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    Oct 2, 2009
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    It takes 46 cycles of the 38kHz carrier to make a pulse lasting 1.2ms.

    38000cycles/s * 1.2ms = 38000cycles/s * 0.0012s = 45.6cycles.
     
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