🚀 go-pugleaf

In article <1jkhpeINNi19@darkstar.UCSC.EDU>, haynes@cats.ucsc.edu (Jim Haynes) writes:
=
=Well I haven't seen enough radar screens in TV or movies to know what they
=look like there, but on a real PPI radar screen, old technology, what you see
=is
=    The trace starts in the center of the screen and goes out radially
=    very fast, so it looks like a bright line.  Actually the line should
=    be pretty dim unless there is a radar return, which makes it brighten.
=    So this part of the display means that in the direction the antenna
=    is currently pointed, time zero is at the center of the screen and
=    maximum time or maximum range is at the outer edge of the screen,
=    and a brightened spot means a radar return at the corresponding distance
=    from the radar.
=
=    The angle of that sweep line with the vertical changes between
=    each trace as the antenna rotates, so that in some length of time
=    between less than a second and several seconds the antenna has
=    gone clear around.  So the whole display shows you, relative to
=    the radar itself at the center of the screen, the distance and
=    angular direction to targets.
=
=    The screen is made of a long-persistance phosphor - but this just
=    means that it's initially bright and decays for several seconds until
=    it is too dim to see.  So targets the antenna has just passed are
=    brightest, and those the antenna is about to come to have practically
=    faded out, and those in between are of intermediate brightness.

Sorry, but last time I looked, there's a second grid, right next to the
screen, that controls whether or not the display is persistent.  At least,
that's the way I remember a Textronix storage tube terminal working (the cursor
didn't leave a persistent image, but any character or graphics you displayed
would).
--------------------------------------------------------------------------------
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.