el cid again -> Axis Radar Reference Tool (3/9/2019 10:24:29 PM)
From The Invention That Changed the World, Pp. 240241:"Kinjiro Okabe...had developed a continuous wave Doppler radar in 1936."
[I think this was the first deployed radar system in the world. It was in widespread use by 1939.]
"The Army and Navy did not even turn to pulsed systems until May 1941, when an observation group visiting Germany
heard reports of British radar. Especially startled, the Imperial Navy quickly launched development of both meter
wave and centimeter models. [Japan appears to have developed the cavity magnetron first, before the British or
French did, but they originally were after microwave communications - something we have come to appreciate.
Still - its development they could apply it to radar when finally they decided they wanted radar. Navy Type 2 Radar
was probably the first mass produced microwave radar in operational use.]
"In November, 1941, just before Pearl Harbor, a three meter early warning set [Type 11 ASEW]took up duty on the
Japanese coast at Katsuura [Chiba Preficture], some sixty miles southeast of Tokyo." I had to change the
availability date of Type 11 radar for this reason. Technical evaluation led me to modify the ranges of the Type A
Radars - the 'continuous wave' radar referred to in the first item. There are two kinds. Both have the official
acronym BDID. BDID Doppler Electromagnetic (continuous) Wave Early Warning Radar has a range of 252 thousand
yards (precisely three hexes) while its larger cousin BIDD Doppler EW Okii ("large") has a range of 756 thousand
yards (or nine hexes). This set has a massive longwave antenna and is rated as static - turning any unit is
assigned to into a static unit even if it otherwise isn't static. These ranges are not quite correct - both are
adjusted to work with 42 nautical mile (84 kyard) hexes. Note these ranges are very large - rivaling EW radars
of later design. But they are not as useful. I have rated accuracy as only 1 - the minimum possible value.
However, I have learned that the normal criticism - including by the author of the book above - is misleading.
Continuous wave interference detectors DO help one understand both raid size and location in two senses: 1) The
duration of the interference was interpreted as raid size. This turned out to be reliable and useful even late in
the war. Japan never failed to sound air raid sirens less than two hours before a major raid (according to POWs
and diplomats resident in Japan).2) The location of the interference must be on an ellipse in which the two
stations are the focal points. This ellipse would be plotted on an aeronautical chart. If the station had
multiple sets (operating in pairs with distant stations) - as was common - there would be two to four such
ellipses on the chart. These, plus lines from likely raid sources, often permitted a reasonable estimate of
where the raids had to be?Except for the one station described above, there was no Type B (pulsed radar) in
Japan when the game starts. So it took work to change this to hundreds of radars by midwar. This was done by
having some other detection devices upgrade, or by defining a later formation that included the radar. Generally,
some optical spotters were replaced with "searchlight" or "fire control" radars - these also being actually air
search radars of limited range when in acquisition mode. I found an astonishing number of Allied radars. These
often appear not to be used, so I will review them. As with Japan, we will create upgrade paths so over time units
will get better sets. But the basic situation is that the game already has a simplified set of the allied radars.
Aircraft radars have all been reviewed and generally are on the correct aircraft. I will review them again
eventually, but not soon. I did add a couple of Allied types last week because they were misclassified as
nav radars. Since they search as airborne surface search, and since nav radar in game has no effect, I
reclassified them as ASS.