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Thread: [EE] 24-bit A/D. Are We in the Twilite Zone Here?
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face BY : Scott Dattalo email (remove spam text)



On Thu, 4 May 2000, Andrew Kunz wrote:

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James, now I know why you were confused. I have to admit that after Andy's
explanation I'm confused as well. First a couple of questions which Andy may
wish to answer. When you say 'time was typically 10-50', what does that
mean? 10-50 milliseconds, 10-50 samples per second? Are you sure that the
formula is correct? (There's a scaling factor missing.)

I suspect if you go back and repeat your experiments with the "digital random
number" stuff removed that you'll get the same results - perhaps even improved
results. From the information you've provided, I can confidently assert that
adding this digital noise is of no beneficial value whatsoever. Instead, the
averaging algorithm removes the random variations in the REAL analog signal
along with the digital variations that were artificially added. Theory aside,
let's look at it practically. If your A/D converter is absolutely solid and
your signal contains no noise, then you'll get the same value everytime you read
the A/D (assuming a DC input of course). The information from the A/D is
constant. There's nothing you can do to increase the information content. If you
add a random value that has a mean of zero, this is not going to affect the A/D
result.


Scott

<Pine.LNX.4.21.0005041216090.3984-100000@tempest2.blackhat.net>

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Subject (change) [EE] 24-bit A/D. Are We in the Twilite Zone Here?

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