🚀 go-pugleaf

In article <1993Jan20.172250.15906@berlioz.nsc.com>, nelson@desktop.nsc.com (Taed Nelson) writes:
=It occured to me last night that in the "real world", ie not on TV shows or
=  movies, that RADAR screens (non-computer controlled -- probably only old
=  ones) wouldn't have that line that spins in circles.  As I reason, the
=  reason that the images (the dots) remain on the screen is due to the
=  percistence [sic] of the phosphor on the screen -- timed so it's about the
=  same as one revolution of the RADAR antenae.  If that spinning line were
=  displayed, then it would also stay around for some period of time --
=  rendering the entire screen completely white/green/whatever.
=
=So, what's the scoop?  Is this some TV-lore, is there some other method, or
=  what?  It would be nice if someone knew for sure.

Ah!  A man who's never used a Tektronix strorage tube terminal!  Here's the
scoop:  For the scan line, you use a relatively low current.  The scope has a
"threshold" current, above which the image becomes persistent.  So:  If you
light the screen with a low voltage, the image disappears immediately.  If you
use a higher current, you form enough of a charge that the storage scope
displays a persistent image.  The current is, of course, controlled by the grid
of the tube.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.