modulation ?

Discussion in 'General Electronics Chat' started by kaznov, Oct 23, 2012.

  1. kaznov

    Thread Starter Member

    Mar 10, 2012
    hi guys

    I was looking for a specific definition or something about modulation as if it's ben used with pwm for controlling the brightness of LED lights please

    what i know is that modulation means that its a combination of carrier signal and data signal but is the carrier one is the constant one and the data one is the modified one ?

  2. crutschow


    Mar 14, 2008
    In PWM the switching frequency is the carrier and the variation in the pulse width with time is the modulation.
  3. electron_prince


    Sep 19, 2012
    modulation means modifying the attributes of carrier signal according to the message (data) signal.

    from attributes, i mean amplitude, frequency, phase etc.

    Edit: Signal carries information and this information is generally in the form of variation of some pattern. For example, in speech signal, the variation is in the form of acoustic pressure. In monochromatic image the variation is in the brightness. These variations are with respect to some independent variables. Variation of acoustic pressure is with respect to time. variation in brightness is in respect to two spacial variables, namely length and breath.

    So your information is in the variation. you decide the variation for your information signal, whether it's the variation in the amplitude or a variation in frequency or phase. impose the same variation on your carrier signal and you'll be able to recover the same information from your carrier.
    Last edited: Oct 23, 2012
  4. kaznov

    Thread Starter Member

    Mar 10, 2012
    thanks guys much love :)