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DVD/CD track spacing and storage capacity

by NeoXx
Tags: capacity, dvd or cd, spacing, storage, track
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NeoXx
#1
May5-14, 02:04 PM
P: 22
Hello,

I finished an experiment of finding out the track spacing of a CD and a DVD.
My laser wavelength was 654nm which I used to calculate track spacing of the optical discs.

I got a track spacing of a CD 1.57um which is close to a real value of 1.6um,
and the track spacing of a DVD 0.72um which is close to a real value of 0.74um.

Then I calculated the storage capacity of both and got 654 Megabytes for a CD which is pretty good but only 2786 MB for a DVD, which is pretty far from its true value of 4700 MB.

What did I do wrong?

Oh here's the worksheet I used to calculate the storage capacity:
http://www.teachengineering.org/coll...t_mhf_tedl.pdf

Regards,

NeoXx
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DrClaude
#2
May5-14, 02:14 PM
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P: 1,354
Quote Quote by NeoXx View Post
Then I calculated the storage capacity of both and got 654 Megabytes for a CD which is pretty good but only 2786 MB for a DVD, which is pretty far from its true value of 4700 MB.
Please show your work.
NeoXx
#3
May5-14, 02:38 PM
P: 22
This is my second experiment where I got similar data as one mentioned in my first post.
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dauto
#4
May5-14, 03:14 PM
Thanks
P: 1,948
DVD/CD track spacing and storage capacity

Not all DVD's store 4.7 G bytes. Some DVD-RAM store 2.5 G bytes. May be that's what you used?
NeoXx
#5
May5-14, 03:30 PM
P: 22
Quote Quote by dauto View Post
Not all DVD's store 4.7 G bytes. Some DVD-RAM store 2.5 G bytes. May be that's what you used?
But as far as I know all DVD types have the same track spacing?

As well, I measured the track spacing similar to a normal DVD, and still got 2.8GB...


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