[Milsurplus] HF SigInt, airborne platform

[Mike Hanz]

On 10/31/2010 3:12 PM, Hue Miller wrote:
> I am wondering why the need for airborne SigInt receiving capability in the upper
> HF range, say above around 11 Mc/s up.

I don't track German or Japanese HF radio equipment, but I I know that 
multiple jammers in those frequencies were produced, like the GO, ARA, 
and ATC based versions - I can provide schematics for all of those.  
There are also even later developments, like the AN/ART-2 at 
http://aafradio.org/countermeasures/ART-2.html , an integrated tx/rx 
jammer, the AN/ARQ-1 at http://aafradio.org/countermeasures/ARQ-1.jpg , 
the AN/ART-6 that I mentioned at 
http://aafradio.org/countermeasures/ART-7.html , as well as guided 
missile jammers like the AN/ARQ-9, AN/APT-6, and the Navy CXOX, XAS, and 
TXA.  If there was no credible threat for the fielding of those sets, 
then I'm wondering why there was no huge fraud, waste, and abuse trial 
at the end of the war....:-)

We also need to be a little more focused on time lines when we are 
talking about intent, IMO.  The GO-5 and GO-6 acquisitions were 
superseded by the GO-7, -8, and -9 by the time this little requirements 
group met in the Autumn of 1939, if I read the tea leaves on that series 
correctly, so the need for RAX Unit No. 3 as strictly a liaison receiver 
requirement *for the last half of 1940* would seem a little puzzling.


>   I regard the talk about RAX as a sigint receiver, or designed for that
> purpose, as fantasy. -Hue

On the first of September, I finally hung it up after almost forty years 
of working in and around Washington DC in the Department of Defense.  
Over those years, I have easily spent hundreds of mind-numbing hours in 
Service and Joint meetings to discuss what kinds of requirements to levy 
on a piece of equipment to meet various threats and operational needs.  
The process isn't perfect...a lot of it has to do with educated guessing 
about technological trends as much as specific developments by potential 
adversaries.  I can well imagine a small group of Navy folks meeting in 
one of the old Main Navy buildings on what is now the Mall during the 
last months of 1939, trying to put together a receiver acquisition that 
would satisfy what they saw was an emerging trend of upwardly moving HF 
frequencies, information collected from Defense and Service Attaches in 
various embassies around the world, and persuasive lobbying for new 
superhet technology (new to aircraft, at least) from the big players of 
the day.  I can also imagine, because I have witnessed the exact same 
thing happening, *original* drivers for a particular piece of equipment 
(like the intelligence community) morphing over the life of a product to 
an entirely different set of customers - simply because the contract 
vehicles were in place and the product satisfied a need that wasn't 
articulated in the original buy.  Todd's excellent breakdown of the 
RAX-1 contract variations reflects this changing need scenario.

What you describe as fantasy is usually the result of good, well meaning 
people trying to read the future with the information they have at the 
time, and subsequent wartime pressures compress changing roles to an 
incredible degree.  I've already reported that airborne signals 
collection in the HF frequencies fell out of favor by the end of the 
war.  I can't say with certainty that the original requirements for the 
RAX were one or the other...my suspicion is that both sigint and liaison 
capability were discussed at these meetings and an attempt to satisfy 
both needs was made, as far as they could do so with the information at 
the moment.  Trying to ferret out original intent through reading a few 
old magazines or popular books appears to me to be a perilous 
proposition in itself, though speculation is certainly an interesting 
pastime.  As for me, I think I'll wait until I see more solid 
documentation before pronouncing definitive conclusions.

Very 73,
Mike  KC4TOS