[ARC5] ARR-1

Wed Sep 17 17:51:22 EDT 2014

Walt, KJ4KV did an excellent ER in Uniform article on the ARR-1/ARR-2 navigation system many years ago.  Perhaps someone can provide what issue it was in.  Anyone heard from Walt recently?

Sent from my iPhone

> On Sep 17, 2014, at 9:58, Mike Everette via ARC5 <arc5 at mailman.qth.net> wrote:
> 
> I tried to send this yesterday but something prevented the message from going out.
> 
> Here is some interesting history regarding the concept behind the YE/ZB system.
> 
> The "Heterodyne Principle" -- that is, using two signals to produce a third signal -- was first conceived in 1901-02 by Professor Reginald Aubrey Fessenden, a Canadian-born radio pioneer who, over the course of his career, held over 540 US patents spread over a wide range of engineering fields.
> 
> Heterodyning, as we all know, is the heart of every communications receiver -- the incoming signal is mixed with a Local Oscillator to produce a third frequency, the IF or Intermediate Frequency.
> 
> However, this wasn't the way Fessenden intended to use the principle.  He patented his concept in 1903 (I believe the patent number is US 706,747; will have to check my research notes), as an "Interference Preventer."
> 
> In Fessenden's system, two signals were transmitted simultaneously from the same location, using separate transmitters.  The frequencies were separated by an amount that would give an audible note when they were received, by "beating" them together at the receiver. The transmitters were either spark-gap type, or used a carbon arc.  This was the only thing available until the debut of the High Frequency Alternator in 1904... an electromechanical device, a dynamo that produced output at radio frequencies up to around 100 kc, and turned at almost impossible shaft speeds.  The alternator was another Fessenden invention; though General Electric ended up getting all the credit for it. 
> 
> Remember, 1903 was before vacuum tubes, before regeneration even.  The most sophisticated detector of 1903 was either the galena crystal, or the "liquid barretter," which was another Fessenden invention -- in essence, an electrolytic device which relied upon a point-contact of a small wire into an acid solution.  It would be ten years later before Edwin H. Armstrong discovered regeneration -- that the triode vacuum tube could be made to oscillate, and provide the "beat frequency" signal at the receiver itself; and not only that, could act as a far more sensitive detector.
> 
> Fessenden's reasoning was that two signals not only would provide a "beat frequency," but also add their out-of-phase voltages to supply more signal strength to the detector.  The arrangement would also make it more difficult for interference -- man made or natural -- to overcome the signal.
> 
> Only problem was, selective fading either had not yet been discovered, or wasn't well enough understood.  (Anyone who's ever messed with RTTY knows how two signals separated by as little as 80 to 850 cycles can independently fade!)
> 
> Getting back to the YE/ZB.  This system represents the ONLY direct application, as far as I am aware, of Fessenden's original Heterodyne principle.  
> 
> The thinking was, "UHF" signals would be line-of-sight only, undetectable by an enemy over the horizon (yeah, right) but perfectly readable by aircraft at altitude.  Two signals were transmitted simultaneously in the 234-258 mc band, separated by a value from 540-830 kc which would be tunable on a low frequency receiver such as the RU, ARA or ARC-5.  All of these could serve as the IF for the ARR-1 (which actually was not a "converter" in the classic sense, but rather more of a "heterodyne detector").  The ARR-2, of course, was a self-contained receiver which had several fixed IF frequencies between 540 and 830 kc.
> 
> As for whether the USAAF ever used the YE/ZB system, I would be inclined to vote No... aircraft were returning to fixed bases, rather than carriers which often moved around.  And by the time of the B-29, LORAN had arrived, which was a much more accurate navigation aid.
> 
> I wrote my Master's thesis in History on the topic of Reginald Fessenden's technical achievements, using his original papers including actual patent application drawings and notes (which are in the North Carolina Archives).  As mentioned before, I have found no evidence of any other direct application of the original Fessenden heterodyne principle.  I think this is ironic, because the US Navy (during WW1) did not place much store in Fessenden's innovative "Sonar" devices for locating enemy submarines (and we suffered a great deal because Officialdumb couldn't see the light); yet the Heterodyne principle played such an important role in winning WW2.
> 
> Thus endeth today's history lesson.  I hope you found it interesting and informative.
> 
> There will be a test later....
> 
> 73
> 
> Mike
> WA4DLF
> 
> 
> --------------------------------------------
> On Tue, 9/16/14, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
> Subject: Re: [ARC5] ARR-1
> To: ARC5 at mailman.qth.net
> Date: Tuesday, September 16, 2014, 1:17 PM
> 
> On 16 Sep 2014 at 11:51, David
> Stinson wrote:
> 
>> There's also intriguing mention of teams setting-up the
> transmitters on
>> beachheads to guide landing craft.  I've probably
> got the cite somewhere in
>> the stacks but I'll bet someone else has seen this.
> D.S. 
> 
> Obviously, both you and Mike know far more about the YE/ZB
> system and its 
> history and usage than I do, but in any case, I still think
> the guys who 
> designed it were sheer geniuses.
> 
> I understand someone has restored a complete system and
> exhibits it at 
> certain gatherings.
> 
> I think I read about that on Mike's website.
> 
> Have any of you ever seen a BC-946B with the added bits
> necessary for use 
> with the YE/ZB system? I never have, but one would think
> that if the Army 
> used that system with the B-29s, there must have been some
> use of the 
> BC-946B...or perhaps the Army used Navy equipment?
> 
> What I don't quite understand is that if that system (YE/ZB)
> was used so 
> extensively, why were there so few BC band receivers made?
> 
> I think I DO know why there are so few left: most were
> hacked to ribbons by 
> those wanting HiFi AM tuners...  
> 
> I have several of those...
> 
> Ken W7EKB
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