mmm@cup.portal.com (Mark Robert Thorson) (01/19/91)
It seems to me that the "imprinting" phenomenon which slowly destroys magnetic tape recordings could be eliminated by winding two tapes onto a spool headed for storage: one tape holding the data and a second tape with something to diffuse the magnetic field such as nickel metallization. Or maybe a fairly thick tape, say 1 mil, would be enough to separate the tape layers and prevent imprinting. Or maybe just winding a blank tape onto the same spool would be enough. Has any of these ideas been tried?
bender@oobleck.Eng.Sun.COM (Michael Bender) (01/20/91)
In article <38204@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes:
->It seems to me that the "imprinting" phenomenon which slowly destroys
->magnetic tape recordings could be eliminated by winding two tapes onto
->a spool headed for storage: one tape holding the data and a second tape
->with something to diffuse the magnetic field such as nickel metallization.
->Or maybe a fairly thick tape, say 1 mil, would be enough to separate the
->tape layers and prevent imprinting. Or maybe just winding a blank tape
->onto the same spool would be enough. Has any of these ideas been tried?
Well, I was reading in an old issue of Videography that they recently found
some "lost" episodes of Fred Astair from the late 50's on COLOR videotape,
which they thought to be the first commercial/broadcast use of color
videotape. The problem was, they couldn't find the machine that was used to
record the tape; it was a 2" quad, but one that had been extensively modified
by RCA engineers, and was no longer in existance. The people restoring the
tapes finally got through to some of the RCA engineers that had done the
modifications in the 50's, and via schematics, notes, and circuit simulation
(!) software, were able to, after about 6 months, convert an old Ampex 2"
quad to read the Astair-format tapes. They said that the tapes were
remarkably well preserved, being kept in a vault and stored properly, and
the images that they got were surprisingly good, considering the era in
which they were recorded. They transferred the old tapes to D-2 and did a
bunch of clean up and editing in that format. Pretty neat stuff, huh? It
would be a bear if everytime you wanted to bring one of your tapes over to
your friend's house for viewing, you had to re-engineer their VCR!!
mike
--
Won't look like rain, Won't look like snow, | DOD #000007
Won't look like fog, That's all we know! | AMA #511250
We just can't tell you anymore, We've never made oobleck before! | MSC #298726krboyce@athena.mit.edu (Kevin R Boyce) (01/23/91)
mmm@cup.portal.com (Mark Robert Thorson) writes: >It seems to me that the "imprinting" phenomenon which slowly destroys >magnetic tape recordings could be eliminated by winding two tapes onto >a spool headed for storage: one tape holding the data and a second tape >with something to diffuse the magnetic field such as nickel metallization. >Or maybe a fairly thick tape, say 1 mil, would be enough to separate the >tape layers and prevent imprinting. Or maybe just winding a blank tape >onto the same spool would be enough. Has any of these ideas been tried? The thick tape is called "back-coated", and is used in the industry. Actually, I get my knowledge of this from a college radio station (soon to be 15,000 watts at 600 feet!), where the only tape we could afford was stuff that got sent to us free with programs on it, so I don't know how common back-coated tape really is. I suspect it is the most commonly used type. It is about 1 mil thick, normally, and certainly is much more immune to print-through, though not completely. Also easier to mark with a grease pencil for splicing. Eewww, physical analog splices! -------- Kevin boyce@amo.mit.edu War. Good God, y'all. Absolutely Say it again... HUH! What is it good for? NUTHIN!
kludge@grissom.larc.nasa.gov ( Scott Dorsey) (02/11/91)
In article <38204@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >It seems to me that the "imprinting" phenomenon which slowly destroys >magnetic tape recordings could be eliminated by winding two tapes onto >a spool headed for storage: one tape holding the data and a second tape >with something to diffuse the magnetic field such as nickel metallization. >Or maybe a fairly thick tape, say 1 mil, would be enough to separate the >tape layers and prevent imprinting. Or maybe just winding a blank tape >onto the same spool would be enough. Has any of these ideas been tried? The BBC once tried archival storage of tape in a similar way. They would wind a thick paper leader and a tape together on a reel so that the layers were seperated. This eliminated print-through almost completely, but it dramatically increased the storage space. Print-through isn't that much of a problem with modern tapes if you use 1.5 mil stuff. With thinner tapes it can be a serious problem. --scott