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Digital vs. Analog Signal Generator

Discussion in 'Electronic Design' started by Jay, Mar 2, 2004.

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  1. Jay

    Jay Guest

    Hi there everyone - just a quick question. We are using the Wavelab
    program to digitally generate a sine wave. Is there any
    advantage/disadvantage to using a digitally-generated signal as
    opposed to if we used an old 1960's style signal generator? Is it more
    noisy, necessarily? This is for a science project.

    Thanks!
    - J
     
  2. Tim Wescott

    Tim Wescott Guest

    Digital is more accurate, and for an affordable signal generator it's
    probably cleaner. These days only a purpose-built high-end analog
    oscillator will be better than digital. I wouldn't expect an analog signal
    generator to do better than digital unless it uses a true sine-wave
    oscillator (assuming you're doing this in the audio range).

    But tubes are more fun, so go with the '60s style.
     
  3. He hasn't stated a frequency range so this is a bit of an assumption.
    There are some rather good ULF oscillators using FET-based active
    devices; the digital equivalent will have the drawback of quantisation
    noise.
     
  4. Tim Wescott

    Tim Wescott Guest

    That would meet my definition of "purpose-built high-end". Then again,
    _anything_ that threatens to win the argument would meet that definition
    :). Also, the lower the frequency the more bits you can economically cram
    into your DAC, so the better the Q noise.

    It really depends on how much money, patience, and experience you have. I
    would expect that the only modern really professional signal sources that
    aren't digital are going to be very high frequency or very narrowly
    targeted. If you need a good signal, have no money but do have time and
    experience then an older signal generator is definitely the way to go. If
    16 bits is enough and you're working in the audio range, then digital is
    probably for you. Same with 12 bits and HF -- get a DDS and have fun.
     
  5. Jim Yanik

    Jim Yanik Guest

    (Jay) wrote in
    It all depends on the specifications of the individual generators.
    Noise and harmonic distortion. RTFM's.
    Or you could compare on a spectrum analyzer.

    Digital generators will generally have a more stable frequency.
     
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