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

[Jim Kinney]

On Wed, Mar 4, 2009 at 9:47 AM, Devnull <devnull at iamdevnull.info> wrote:
> On Wed, Mar 4, 2009 at 09:35, Jim Kinney <jim.kinney at gmail.com> wrote:
>> 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.
>>
>
> Please, correct me if I am wrong, but I thought that CDs are written
> with CLV (Constant Linear Velocity), so that the drive modulates the
> CD revolution speed in such a way that data passes over the head at an
> equal frequency. [1] When I use the eject command, I am changing the
> high level speed (i.e. 1x, 2x, 3x, 4x), and not the RPM speed. If you
> want, I can provide you with a copy of my data.
>
> [1] http://everything2.com/e2node/Constant%2520Linear%2520Velocity
> --


Yep. See here: http://everything2.com/title/CD-ROM%2520speeds

Not sure which is true now but CAV would explain the results you see.
CAV vs. CLV is part of the CD+- designation mess as well.
> -
> /dev/null
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-- 
-- 
James P. Kinney III