how a simple bit/data synchronization work?

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

  1. leonheard

    Thread Starter Member

    Jan 8, 2013

    Can someone please explain to me how a simple bit/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. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    I would expect the receiver to start clocking the bits into a shift register when it sees the first bit arrive. When the shift register is full (count the clock cycles) the pattern can be latched and read, the shift register would then be cleared ready for the next set of bits to arrive.
    leonheard likes this.
  3. crutschow


    Mar 14, 2008
    You need a gap in the data or a specific word to provide the signal to synchronize the receiver with the transmitter.
  4. cmartinez

    AAC Fanatic!

    Jan 17, 2007
    Yes, either an elapsed time in which no data is received that would be interpreted as a communications reset by the receiver, or a unique sequence of bits that would mean start of communications. It all depends on the specific protocol being used.
    leonheard likes this.
  5. leonheard

    Thread Starter Member

    Jan 8, 2013
    THANKS! i will try that