[ARC5] YG/ZB Demo
Mike Hanz
aaf-radio-1 at aafradio.org
Mon Jul 4 18:01:11 EDT 2011
> Mike wrote of the YE/ZB:
>> The sector edge characteristics are not formed by narrow beam width,
>> but by precisely switching the audio coding at each angle desired.
> Still, Mike, if the YE beam is too wide, or the ZB is too close to the
> YE, multiple sector IDs would be received at the ZB.
Michael, Michael...how soon we forget. ;-) Heh, heh...the answer is
clearly stated in the NRL discussion of the system. You use a
combination of the RF gain control with the BFO turned on and that most
magical of modern computers - the Mark I Mod I human brain and ear
combination, to determine which beam is loudest. I know we're all into
perfect solutions to complex problems these days, but sometimes the
simplest is best. I don't know why you wouldn't use a control box...in
fact it's required of the ARR-2 to select the channel number before the
mission flight, and RF gain as you approached the carrier. Similarly,
you'd need an ARA/whatever control box in addition to the ARR-1 pilot's
control box distant/local switch to make gain adjustments for the ARR-1.
>> 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*.
> But...it appears that the specific individual YE beacons of the carriers
> in a battle group were discriminated only by FREQUENCY in the 234 to 258
> MHz YE/ZB operating band.
That's correct. And the implication is? That brings up another
question about the previous postulate - if you could only get in the
general *vicinity* of an entire battle group that covered a 30 mile
circle, why would each carrier have its own discrete frequency? I can
just imagine the flight groups coming back from a 250 aircraft raid to
say four carriers, all demanding radar position reports and guidance
back to *their* carrier...yeah, sure...that'll work great! :-)
> There's a pilot's report of YE/ZB use during the battle of Midway at:
>
> http://www.cv6.org/company/accounts/jmccarthy/
>
> These statements indicate some intersting details of YE/ZB use:
>
> (1) YE/ZB frequency was DIFFERENT for each carrier in the task group.
> (2) YE/ZB sector IDs were IDENTICAL for each carrier in the task group.
> (3) YE signal strength was controlled (reduced) on approach to reduce
> multiple sector ID reception by lowering aircraft altitude.
> (4) When the YE was very close on approach, all sectors were received
> at the ZB.
I'd agree with that, but all the sectors wouldn't all be received with
the same signal strength as the transmitting antenna rotated. I'd also
speculate that the backlobe of the antenna was pretty far down. Of
course, there are some pilots that couldn't find the broadside of a barn
if it smacked them in the face, so there are probably varying degrees of
aptitude in determining the loudest sector. It's a little like swinging
a loop antenna - despite a fairly broad angle indication, you can
usually get the maxima or minima pretty close based on perceived signal
strength, can you not? At least it always seemed like you could with a
bit of RF gain control jiggling.
> I think it is doubtful that a demo setup where the ZB antenna is physically
> close to the simulated YE, that one could avoid the situation described at
> the end of the quote above, where are sectors are received.
I rather like John's suggestion of using LEDs, though it might be
interesting to try a TS-24 with a back reflector to the little whip and
see if some dimensional adjustments could be made to achieve the goal.
The manual suggests ten feet from the test set, so that's a good start.
> And it is
> essentially impossible to discriminate at the ZB and its BCB receiver on
> the basis of signal strength, except that as the signal grows stronger,
> more sector IDs are received.
Everyone is entitled to their speculation...some folks can hear patterns
in noise better than others, just as some can distinguish patterns in
images, or odors, or tastes better than others... :-)
- Mike
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