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Ir led modulation

Discussion in 'General Electronics Discussion' started by Pini Deri, May 11, 2014.

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  1. Pini Deri

    Pini Deri

    May 11, 2014
    Hi guys,

    Is there any communication protocol for 1Mhz or greater (IR LED) ?

    Does the frequency effect the range of communication ? (i.e the greater the freqcuency the less range or the opposite)

    tnx very much!
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    There are thousands of protocols.
    Which protocol is suitable depends on you application. Parameters like range (your next question), power consumption, reliability etc. come into play. For IR communication you can use any protocol that is based on purely digital (0/1) signals. Transmitting analog signals via IR is possible but very unreliable.
    You should distinguish between modulation and coding.
    Modulation is the way the information is transformed from the elctrical form into the infrared light. Examples of possible schemes are pulse width modulation (PWM) or pulse position modulation (PPM) (ask Google for details).
    Coding is the way the information is encoded (and decoded on the receiving end) to ensure reliable data transmission. Examples are a parity bit as used in UART communication (a very simple encoding scheme with low reliability), cyclic redundancy check (CRC) to provide an inproved error detection mechanism (although no error correction) or RSA block codes to allow error detection and correction. Many other schmes exist. Google for details.
    Depending on your requirements you can combine modulatin schmes and coding schemes for a best fit.

    This article, although meant to be used in connection with IR remote controls at data rates much lower than 1 MHz can give you an idea about IR modulation and coding.
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    Yes: IrDA:
    Yes. The higher the data speed, the shorter the range, and the more critical the path.
  4. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    Shame I hadn't chosen to do my IrDA range tutorial first. Instead of the disaster currently posted under OP-amp stability!
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