EF50 was Re: radar history

William Donzelli wdonzelli at gmail.com
Sun Mar 4 16:58:35 CST 2018

:> The high frequency power tubes were required for better spacial
resolution. My understanding was that major difference between the
German radar and allied was that the Germans had a single trace, like
a time domain reflectometer. The allies had a rotating image that is
similar to what we see on current radars, today.

Both sides had the displays you describe. The first is called A-scope,
and the latter PPI (Plan Position Indication). Consider that early
radar, well into the 1950s, was actually pretty horrible. PPI back
then often resulted in a screen full of indistinct smudges, so nearly
every search radar had the "old" A-scope, where the operator would use
a cursor* and get a very accurate range and azimuth reading.
Basically, the PPI scope was good for "the big picture" "show me all
the information", and the A-scope was good for getting the information
that was actually useful.

> The cavity tuned magnetron was clearly an issue because it allowed them to run at a higher frequency than the split plate magnetron. Both were significant changes in how things were done.

Significant, but only sometimes significant. Higher frequencies
produced by magnetrons were useful for bombing and gun laying (anti
aircraft and naval guns) as it improved range accuracy greatly, but it
did nothing for air search radars. VHF radars (with triodes) were
still in front line service until the 1950s, simply because they did a
much better job at illuminating aircraft.  Germany often gets the
short end of the stick when it come to radar tech in World War 2, but
towards the end, their (non-magnetron) air search radars were some of
the best. Why? Because that is what they needed with their skies full
of Allied bombers.

The graphical real-time cursor and joystick, in one or two dimensions,
has its origin in World War 2 radar systems. It is astonishing how
many historical accounts of early computer graphics do not mention


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