[ale] OT: CD drive and revolution speed correlation?

[jim.kinney at gmail.com (Jim Kinney)]

I'm pretty sure the rotational speed for any given value is not fixed
but variable based on head location. If speed is fixed, bit rate
increases with increased distance from spindle. I would expect the
data rate to have a factor of pi in it somewhere since it relates to
radius and circumference.

On Wed, Mar 4, 2009 at 8:13 AM, Devnull <devnull at iamdevnull.info> wrote:
> Hi, this is kind of off-topic, but I thought that you might be able to
> shed some light on this. I have done a science project that determined
> the correlation between the rotation speed of a CD and the data speed
> of the CD. I used the eject command to change the speed of the CD
> drive, and the dd command to read all of the data off the CD. I even
> used an Ubuntu CD for the tests :) I would set the CD drive to every
> speed between 1 and 45, and record the time, bps, etc. Now my question
> is this: When I plotted the graph, the graph indicated that there was
> an exponential correlation between the data, but from what I know,
> there should be a linear correlation. What I thought was that 2x is
> twice the speed of 1x, 3x is thrice the speed of 1x, etc. This would
> suggest speeds proportional to x, but I am not getting these results.
> Please correct me if I am wrong. Thanks.
>
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James P. Kinney III