What is the minimum data rate ?

Discussion in 'General Electronics Chat' started by sama3505, Jun 10, 2016.

  1. sama3505

    Thread Starter New Member

    Jun 10, 2016
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    Include the all equations how to do this.
    What is the minimum data rate needed if you wish to sample a 10V analogue signal with at least 20 mV precision and 512 samples per second?
     
  2. Marley

    Member

    Apr 4, 2016
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    10V divided by 20mV = 500 steps minimum in the ADC.
    500 steps could be represented by 2^9 bits (actually = 512). So a 9-bit binary value.
    Transmitting 9 bits 512 times a second = 4608 bits per second.
    This is an absolute minimum. In reality, there would have to be extra bits transmitted for timing and identification.
     
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  3. sama3505

    Thread Starter New Member

    Jun 10, 2016
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    so if we get 30 steps ,are we getting it as 2^5 =32 ,so its a 5 bit binary value ? right?
    and did you multiply that 10v/20mv =0.5 x 100 as well ?
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You have to take the mili in account.
    It will be 10 / 0.02 = 500.

    Bertus
     
  5. Marley

    Member

    Apr 4, 2016
    142
    40
    Correct, 30 steps can be represented as a 5-bit binary value.
    With 30 steps, the resolution will only be 10V / 30 = 0.333V (or 333mV).
    So for more resolution you need more steps and more bits. To more accurately represent a changing analog value you need:
    • more steps = more bits
    • sample more often = more samples per second
    So, more accuracy = greater data rate. This is one of the first rules of information theory.
     
  6. sama3505

    Thread Starter New Member

    Jun 10, 2016
    18
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    Thanks

    can you have a look on this problem as well.
    http://forum.allaboutcircuits.com/threads/how-to-find-the-torque-constant.124860/
     
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