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Analog-to-Digital COnverter

  1. May 2, 2010 #1
    Hey all,

    I am looking for any expert who knows bout the ADC.
    I am planning to convert my audio analog signal to be digital signal, then i m goin to transmit that digital signal by using LASER DIODE.
    However, I cant really understand the circuit, how to connect that for transmission.
    As i know, it is converted for computer used purpose at ADC. anyone know how to do with the ADC for transmission in free space??

  2. jcsd
  3. May 2, 2010 #2


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    Suppose you had an A to D converter that converted an analog signal to 8 bit data. This would appear on the 8 output pins of the integrated circuit.

    You could take these 8 outputs to the 8 inputs of a shift register and apply clock pulses to send them, one at a time to the serial output of the shift register.

    These outputs could be used to switch a laser on and off.

    This is the theory. Actually doing it fast enough to keep up with audio and synchronizing a receiver to decode it would take some pretty serious development work.

    There is a lot of interest in this. I just Googled "laser audio link" and got lots of plans for doing this sort of thing. Not necessarily digital, but they claim to get good results.
  4. May 2, 2010 #3
    from my datasheet, i found the data output(Dout) is always connected to the three-wire serial interface with data input (Din) and Serial Clock Input (SCLK). It really confuse me, how am i suppose to get the data output...
  5. May 2, 2010 #4


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    Sounds like you already have a serial output.
    Which type of A to D converter are you using?

    Here is some descriptive explanation of one type of serial A to D converter, the TLC0831:

    A conversion is initiated by setting CS low, which enables all logic circuits. CS must be held low for the complete
    conversion process. A clock input is then received from the processor. An interval of one clock period is
    automatically inserted to allow the selected multiplexed channel to settle. DO comes out of the high-impedance
    state and provides a leading low for one clock period of multiplexer settling time. The SAR comparator compares
    successive outputs from the resistive ladder with the incoming analog signal. The comparator output indicates
    whether the analog input is greater than or less than the resistive-ladder output. As the conversion proceeds,
    conversion data is simultaneously output from DO, with the most significant bit (MSB) first. After eight clock
    periods, the conversion is complete. When CS goes high, all internal registers are cleared. At this time, the
    output circuits go to the high-impedance state. If another conversion is desired, CS must make a high-to-low
    transition followed by address information.

    So, you could take the output from the data-out line and switch your laser with it.

    Did you have a look at any of those circuits on Google?
  6. May 2, 2010 #5
    i already selected the ADC by myself which is AD 7811.
    However, i wonder that sampling rate is able to be controlled although it stated it is 350kSPS in the datasheet.

    Must i connect the ADC with the microcontroller or microprocessor? I was thinking that, i can directly get the data out from the Data Output pin.
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