[Milsurplus] Spoof countermeasure against Japarception of proximtyity fuze signals

[Bruce Gentry]

Just how possible was it to receive the signals from the fuzes when they 
were hurtling toward you? The transmitters were of fairly low power, a 
good receiver would be needed, and even more challenging, knowing where 
to tune for a signal that might only last for ten seconds or so. How 
good was the state of the art for receiving UHF signals in 1944?  This 
question has come forward to me in the past week when I saw a 
Hallicrafters S-36, found it interesting, and  wondered if it was worth 
trying to find one of my own. How sensitive were receivers using acorn 
tubes or other UHF tubes of that time? I can attest from direct 
experience a BC-639 will break squelch with 3-5 microvolts of signal, a 
far cry from .3-.5 microvolts for good AM and full quieting FM of many 
two meter receivers in the 1970s. It was good enough to consistantly 
receive a ten watt transmitter on an aircraft in the traffic pattern. 
Because the no-signal hiss was so low on a BC-639, we often left them 
with the squelch open. How good were Japanese UHF receivers at that time?

       Bruce Gentry, KA2IVY

On 11/13/17 10:52 AM, Jack Sullivan via Milsurplus wrote:
> My original question on this topic did not relate to the jamming of 
> these projectiles - it had been shown that a modified APT-4 in a B-17 
> would cause prematuredetonation of these shells as observed from the 
> aircraft. My question related to U.S. concern that the Japanese could 
> pick up the signals radiated by the shells & develop in turn their own 
> jammer or other countermeasure. I’ve read that in order to counter 
> this & to confuse potential Japanese eavesdropping, U.S. Navy ships 
> transmitted a number of ‘spoof’ signals in order to confuse them. This 
> is obviously quite a different topic than jamming. I’m looking for any 
> information relating to U.S. spoof transmissions & associated 
> equipment used at Okinawa.
> Jack
>
>
> ______________________________________________________________
> Milsurplus mailing list
> Home:http://mailman.qth.net/mailman/listinfo/milsurplus
> Help:http://mailman.qth.net/mmfaq.htm
> Post:mailto:Milsurplus at mailman.qth.net
>
> This list hosted by:http://www.qsl.net
> Please help support this email list:http://www.qsl.net/donate.html



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20171113/e44a1a55/attachment-0001.html>