[Laser] Lasers vs LEDs & ARRL contests

[John E. Matz]

Good evening,

As the "winner" of the 1998 Illinois Section "above 300 GHz" band in the 
September VHF QSO Party, with two whole optical contacts (hey, I'm lucky 
living 100 yards from a grid border), I would like to toss in my two cents 
on this topic.  I hate being stuck with "lasers".  I have used gas tube HeNe 
and solid state diodes, but as long as they have seemed to define 
"coherence" as what a laser can do, there were no other alternatives.  I 
think other light sources should be allowed.  LEDs are fairly monochromatic 
and are available in higher power outputs than lasers, but without the high 
power density.  As has been stated by others, coherence goes away after a 
few feet in air.  And the rules do not state that you can't use an optical 
fiber.  The rule that states that amateur license is required and at least 
one stage of electronic detection on receive effectively eliminates 
"flashlights at 20 paces to anyone" and "copy by eye", but does not 
eliminate other light sources like LED's.  So I guess I would delete the 
need for "coherence" in the source and add that communication should be 
through the air, free-space-optics FSO is the current term, I believe.

My two cents,
John Matz KB9II

----- Original Message ----- 
From: <W0ZQ at aol.com>
To: <laser at mailman.qth.net>
Sent: Friday, July 18, 2008 6:59 PM
Subject: [Laser] Lasers vs LEDs & ARRL contests


> Hello to all Laser/light enthusiast.
>
> As some of you may  know, I am the ARRL's Dakota Division VHF/UHF Contest
> Committee (VUAC)  representative.  I am seeking your comments.  One of the 
> items
> that  has been under discussion by your VUAC is the ARRL General VHF 
> Contest
> rule 1.12  that states "1.12. Above 300 GHz, contacts are permitted for 
> contest
> credit only  between licensed amateurs using coherent radiation on
> transmission (for example,  laser) and employing at least one stage of 
> electronic
> detection on  receive."  This rule requires that the contact be made by 
> licensed
> amateurs  and that the detection requires at least one stage of 
> electronics, that
> much  seems fairly clear despite whether you agree or disagree with that 
> part
> of the  rule.   What is less clear is the requirement that the source use
> "coherent radiation" and "(for example, laser)".  How coherent is coherent 
> ?
>
> What I would like your comments on is this.
>
> 1.   Given  this rule as it is now, does it include or exclude the use of
> narrow band  LEDs like the Luxor.  I am no optics expert but it seems to 
> me that
> some of  these newer power LEDs are very close in coherence to really poor
> lasers.   Does the current rule have enough latitude to include narrow 
> band LED
> emitters ?
>
> 2.  IF we could rewrite the rule, what should  the rule say ?  Do we want 
> to
> be much more specific and tighten the rule so  it states "Laser only", or 
> do
> we want to open the rule up to specifically allow  the use of newer
> technologies like power LEDs ?    In either case  what should the rule say 
> ?
>
> It seems that on the one hand we don't want to allow a blinking white 
> light
> bulb, but if not that where is the line ?
>
> Again, your  comments and perspective are most welcomed.
>
> 73, Jon
> W0ZQ
> Dakota  VUAC Rep
>
>
>
>
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