[ARC5] YG/ZB Demo

[Mike Hanz]

It seems to me that y'all are missing the central design point, not to 
mention comparing apples and oranges - this ain't no VOR station in form 
*or* function.  The sector edge characteristics are not formed by narrow 
beam width, but by precisely switching the audio coding at each angle 
desired.  The RF carrier smooshes its way on around with a pretty wide 
beam.  The original was a 48" long Yagi style beam with 1/4 wave 
vertically oriented elements and a parabolically arranged reflector 
screen of the same size elements - all about a foot long.  The reflector 
they ended up with was, as Jack mentioned,  a prototypical 2' x 2' 
semi-cylindrical TV antenna reflector for the old UHF band, primarily to 
reduce backlobe of the signal.

There is *no* discussion in the literature about these systems that 
suggest you could *only* find the general vicinity of the battle group - 
it was always about finding your particular *carrier*.  The amphibious 
adaptation of the system speaks of finding a specific point on the beach 
from landing craft several miles out, and up to thirty of these systems 
for a typical landing at multiple points in a long beach!  BTW, I see 
where Bell Labs takes some credit for the system as well as NRL...guess 
there were a lot of folks producing it by the end of the war.

Don't forget that the closer you get to the carrier, the smaller the 
radial circumference you are flying within to maintain the code letter, 
so it is self-adjusting to closer and closer ranges.  As a result, it 
appears to me that Dave's idea could actually be implemented with a very 
simple rotating stub on a disk, using a central cylindrical reflector if 
backlobe reduction is considered useful.  For that matter, the only 
reason for the rotation is for displaying the concept of the rotating 
antenna - the fixed antenna on the TS-24 could simply be used but it 
doesn't have the "pizazz" of a demo with motion.  Of course, the 
coordination of the modulation sectors with changes in the morse code 
letter being sent would take some thought, especially if all the other 
info Jack mentioned being sent is included.... :-)

  - Mike

On 7/4/2011 11:07 AM, J. Forster wrote:
> Good point.
>
> You might be able to "fake it by using an LED (possibly IR) and
> photodetector. You can modulate those in the BCB, but probably not at 200
> MHz.
> You might also think about a microwave simulation, either X or K band.
>
> ========
>> I would really doubt that with any antenna system you could devise that
>> you could get suitable resolution to determine bearings for distances of
>> less than a few miles.  Anyone who has tried to turn onto a specific "To"
>> heading within a few miles of a VOR station can tell you how difficult
>> that can be, and VOR is far, far more precise than YG/ZB.  Signals
>> bouncing off of various objects will make it much more difficult at ground
>> level.
>>
>> The YP/ZB system must have been desigend to enable pilots to find the
>> fleet, not individual ships.  It was not common, but neither was it
>> unheard of, for pilots to accidently land on the wrong carrier, not
>> realizing where they were until they went below and discovered the pilot's
>> ready room had been moved in their absence.
>>
>> I think you are going to need a transmitting station at least a mile away,
>> and probably much more than that, to be able to discern different
>> headings.
>>
>> I recommend you build at least two transmitters, operating on different
>> frequencies, and at different locations at the outer boundaries of the
>> hamfest grounds, and each with a different code.  This also should be
>> easier than building a rotating antenna with encoder.
>>
>> Happy 4th of July, Everybody!
>>
>> Wayne
>> WB5WSV
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