[ARC5] YG/ZB Demo

[J. Forster]

For your consideration:

http://www.jensign.com/opto/ledmodulator/index.html

-John

===============



> 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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>>
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>
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