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how a simple bit/data synchronization work?

Discussion in 'General Electronics Discussion' started by leonheard, Dec 29, 2014.

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  1. leonheard


    Jan 25, 2013

    Can someone please explain to me how a simplebit/digital/pulse code/data (whatever the name is)synchronization in the receiver work?

    the transmitter and receiver is a simple 37khz IR ( the IR modulation and demodulation part i know how it works so i dont need help there... )

    example if i have a simple synchronous flip flop with 4 bits with a pulse clock of 15khz...
    0 0 0 0
    0 0 0 1
    0 0 1 0
    0 0 1 1
    0 1 0 0
    0 1 0 1 etc...

    and the "Receiver" have also a 4 bits flip flop with a a clock of 15 khz, (okei this is the difficult part ) when the first data from the transmitter example : 0 0 1 1 enters the receiver`s circuit how the receiver "knows" where that 0 0 1 1 code goes?!

    did i miss something here? i hope you can help me...

    ps. All that without a microcontroller :)
  2. BobK


    Jan 5, 2010
    The simplest method of synchronization is used in serial asynchronous data transmission, usually just called serial lines. This works by keeping the logic level in one state (typically high) when no data is being transmitted. Then, to transmit data, the line goes low for clock 1 period (this is known as the start bit). After that, the line goes low or high for the next N periods (usally 8) and finally returns to staying high. The clocks on the transmitter can stay synchronized enough for this short, 8-bt transmission, and are re-synched by the start bit before each subsequent transmission.

    hevans1944 likes this.
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    This seems like a pretty strange question.

    Decoding the data in an infra-red remote control datagram is normally done after the 37 kHz carrier has been removed. You can get receiver modules that produce a demodulated output signal ready for decoding by a microcontroller. The protocol is self-clocking, either with a start bit and biphase coding (RC5) or pulse length modulation (most other schemes), and the receiver just starts timing from the first active-going edge on the datagram.

    What do you want to do? Tell us about the whole project, not just one little part of it. And why do you want to do all this without a microcontroller?
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