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PostPosted: Sat Oct 22, 2005 10:00 pm 

Joined: Thu Dec 28, 2000 3:56 pm
Posts: 159
Location: CYVR Hub
"YXY VOR 067 R is occasionally subject to severe scalloping"

Pray tell, what is scalloping, what causes it and why is it occasional?



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CVA1122 Ben Wegner © Copyright. Any reproduction of all or part of this post is sheer stupidity.
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PostPosted: Sat Oct 22, 2005 11:03 pm 
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Joined: Fri Dec 31, 2004 9:18 am
Posts: 284
Location: Prince George, B.C.
This is the best I can find : Don't think it helps much ?

"A series of indentations or erosions on a normally smooth margin of a structure."



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PostPosted: Sun Oct 23, 2005 4:27 am 
Here is a good description of signal scalloping in a VOR..

Signal scalloping

Cheers Rod


  
 
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PostPosted: Sun Oct 23, 2005 1:37 pm 

Joined: Thu Dec 28, 2000 3:56 pm
Posts: 159
Location: CYVR Hub
Good stuff, gents.

"VOR signals are transmitted on line-of-sight. Any obstacles (buildings, mountains or other terrain features, including the curvature of the earth) block VOR signals and restrict the distance over which they are received at a given altitude. This can result in a sudden scalloping fluctuation of the cockpit indicators -normally for short time intervals."

So, I (idly) wonder, if it caused by terrain features or the curvature of the earth, why would it only be "occasionally" in the case of the YXY VOR? Terrain and curvature seem rather permanent to me. Perhaps the VOR, in this case, is located beside a train track or an elk migration trail? The theory being, when the train (or elk) passes it would cause fluctuations in the signal.

Go figure. The North is full of mysteries.



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PostPosted: Sun Oct 23, 2005 10:09 pm 
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Joined: Fri Dec 29, 2000 7:01 am
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Location: Wembley, Alberta
Having been in the North a time or two, I have experienced problems with all radio communication (Cell phone, Two-way radio, and even GPS) from time to time. Seems to me, on a clear night when the Northern lights are REALLY going, radio signals are interfered with...

Purhaps a similiar phenomenom effects VOR signals?



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CVA51-Keith Henry
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PostPosted: Mon Oct 24, 2005 12:14 am 
Heya Ben!

Scalloping of the type you're asking about is the result of reflection and not "blocking." The effect is a "wavy" or "jumpy" indication on your instrument, which is caused by ambiguous signals.

A couple of big factors in such signal reflection are mountainous terrain and, you guessed it: snow cover.

So, to answer your 2nd question, I figure that it's the "occasional" snow that causes the "occasional" scalloping.

Cheers!

Gary




Edited By Gary Madore on 1130113126


  
 
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PostPosted: Mon Oct 24, 2005 4:47 pm 
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Joined: Fri Dec 31, 2004 9:18 am
Posts: 284
Location: Prince George, B.C.
Keith, here is an expanation for what you have expeirianced. This gets worse the farther north you are.

When the particles ejected from the Sun interact with the Earth's own protective magnetic shield, its magnetosphere, the impact can be observed as aurora. Gases in the upper atmosphere become excited and glow. These are most commonly seen near the Earth's polar regions where the magnetic field lines guide the charged energy toward Earth. If viewed from high above Earth, they appear as ovals. Images taken by astronauts in the space shuttles show the depth of aurora. Other impacts from this energy pouring into the Earth's atmosphere, include short-circuiting power grids that cause blackouts, disrupting communications, damaging satellites, and endangering astronauts with radiation.

For more info go to....http://sohowww.nascom.nasa.gov/



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