You may be a geek if. - test-drb@ccmp.vtda.org

21 Feb 2001

...
 252KB/minute. What is the audio length of a vinyl?
I'm not sure, but if
we make a nice round 60 minute, then we're looking at about 15meg. 

assume 30minutes a side is the high end.

...

duplex. LProms would be a read-only system. Also, the figure of 33300bps
is based on a modem audio resolution of 2400baud. I don't know the audio 

300 baud was hard to do!  bandwidth extends to in excess of 15khz but,
 the signal to noise level is poor.

...
 Next up, we look at the modulation/demodulation to use.
We'll want a
compression that takes best advantage of the medium. (I suspect v.42 is
not it!). Lastly, LP's are stereo - so that either immediately doubles
our capacity (assuming L and R can be kept 100% independant. If they can't
...
 be guaranteed to be kept seperate, then I'm sure
capacity could still be
increased by using L and R as checksums against each other or something ;)

No do able as L & R signals are sum and differenced running around
25-30db
under best conditions.  So there will always be some of the other channel
present in the other.

...
 Problems with LProms are quality of reading - you run a
very real risk
of bitrot if your needle is of poor quality. Also, you'll need some
way to sync the end of sideA with the start of sideB - there is some
data loss there. (this could probably be kept to a minimum by using the
leadin/leadout areas :) 

Stylus is a small part of the story, the Vinyl wears, deforms from actual
use, and pressing errors.  Leadin/out are not a real factor compared to
the actual cuts.

Records suffer from:

    Wow, slow variations in speed.
    Flutter, fast variation in speed
    Noise, both hiss and pop
    distortion both in phase and waveform.

These vary from pressing to pressing and decay with use of the
master.  The quality of the base is important (hiss and pop noise).
Also the acutal recording and transscription process prior to cutting
the master can introduce artifacts.

I still have a rather extensive collection of records from the pre-Altair
era and have invested in keeping my Yamaha running as it can.
You had to be very careful to keep a some 30+ year old copy of
Iron Butterfly listenable.

...
 So, did I have an answer in all that?  I'm pretty
sure you'd get 15meg on
...
 a vinyl easily, and could quadruple that figure with a
bit of effort :) 

With modern DSP technology better is possible but there are far newer
technologies that are proven.

Allison