[R-390] AN/URM-25s

[rbethman]

I accept the description.

However, Roger R. and his equals that worked on this specific 
combination of AN/URM-25s and R-390s/R-390As, achieved some very 
impressive results.  The got very good S/N ratios, and high sensitivity.

They didn't piddle around with Faraday cages and similar Tempest 
methodology.

Do I know about these methods?  Certainly.  My reference to the same 
period and working with missiles, radars, and their sensitivity/accuracy 
was just another look at the entirety.

1) The MTR had to lock on to the 12" cone with a required minimum 
distance of 1 mile from the IFC area to the Launching area.

2) It had to maintain this "lock" from the initial lock at missile 
erection in prep for launch.

3) This lock , track, and data link must be maintained from launch to 
intercept.  If the lock was lost, the missile was programmed to 
self-destruct.

4) This had to sustain the initial acceleration, continue until maximum 
velocity was reached, (over Mach 3), to an altitude around 70K feet or 
more, and at a distance of around 300K yards.

This was intended simply to provide an example.

The entire process of loading a missile onto the elevator, already 
having arming plugs inserted, raised to the surface, and slid along the 
rails to where it would be raised to the launch angle, was interspersed 
with a constant litany of testing for stray voltage with sensitive devices.

This was necessary to ensure safety to personnel, and the possible loss 
of a missile due to accidental ignition of the booster by the squib.  
Obviously you really don't want a booster lighting up when it isn't the 
right time and place.

All of this was being performed while the Target acquisition radar was 
sweeping, the TTR, (Target Tracking Radar), TRR, Target Ranging Radar), 
and the MTR were ALL in play.

The numerous signals permeated the area.  There were multiple Missile 
Batterys doing the same thing with the same numbers of pieces emitting 
RF.  There were up to 5 IFC areas all doing this at the same time, 
engaging targets, acquiring their missiles, and targets.

If there was ANY issue of RF that would interfere with all of this 
activity, the entire system would have been compromised.

There was an annual exercise where we had U.S. Aircraft of many 
different types that would come in with jamming of every type possible 
emanating from B-52s, SR-71s, and RB-57s, while trying to penetrate us, 
and us performing target ID, acquisition, and simulated interception.

Whenever we went through this, the IBM system where my wife worked a 
number of miles away from the Air Defense Command Post, would have the 
huge search radar scramble their computer to the point that the attached 
IBM line printer would begin shooting paper out at a rate that caused 
the paper to hit the ceiling.

The AN/FPS-24 search radar had been kicked into high output AND its 
Frequency Hopping mode.  This was what the *REAL* thing would be like.  
Therefore, all the capabilities of the Command Post, along with similar 
capabilities of the Missile Firing Batterys, were turned loose and 
running at MAX along with all Battle Short switches flipped on so that 
even if some dumb light bulb, switch or other item would perhaps fail, 
system continued to operate.

The computers, radios, and all of the above were going constantly, with 
our microwave links amongst the entire Defense Artillery Group, AND the 
links to NORAD with the SAGE/BUIC system.

This was the harshest RF environment that I have ever worked within.  RF 
leakage was  highly prevented even with all the openly exposed items.  
Yet - there never was a single RF cage/Faraday shield in existence.

How do you place such devices around either Missiles or Radars?

So through this together, and you have a recipe for disaster.  However, 
it simply did NOT happen!

There are much more things that we had concerns over, and had to place 
close attention to.  The warheads were under this environment also.  
They were not dummies.

Bob - N0DGN

On 3/2/2012 6:57 AM, 2002tii wrote:
>
> Exactly.  Signals getting out of a box other than through the
> intended port, and signals getting into a box other than through the
> intended port, are both leakage.  When you are trying to measure the
> maximum sensitivity of a radio, it is a problem if your sig gen
> "leaks out" and your receiver "leaks in."  [This is because the
> signal that leaks out of the sig gen leaks into the radio, so the
> actual signal the radio is receiving -- some through the antenna
> connector plus some by leakage -- is stronger than the signal the
> generator is putting into the receiver's antenna terminal.  If you
> think that what is going into the antenna input is all there is, you
> will be fooled into thinking that your radio is more sensitive than
> it really is.]
>
> Of course, "leakage out" and "leakage in" go hand in hand -- if there
> is a leakage path in, there is also a leakage path out, and
> vice-versa.  But *when we are measuring receiver sensitivity,* we
> generally do not care about RF energy getting out of the radio
> because it generally does not disturb our measurements (regenerative
> receivers, direct conversion receivers, and receivers with very high
> RF gain and poor shielding of the RF section are exceptions).  We may
> or may  not care about signals getting into the sig gen, depending on
> what mischief they cause (do they come out of the sig gen output?  do
> they cause distortion or spurious responses?  etc.).
>
>
>
> Best regards,
>
> Don
>