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Rob Spiegel
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Re: Maybe not so straight forward?
Rob Spiegel   1/3/2012 3:31:25 PM
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Good point Naperlou. This case of Sherlock Ohms really does require both experience and logic. Most of these entries require some combination of the two. I would imagine the experience comes through as a form of intuition, while the logic is a cool-headed effort to look at a system without assumptions. 

naperlou
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Re: Maybe not so straight forward?
naperlou   12/31/2011 6:22:55 PM
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As with many aspects of satellite communications and control, there are issues that one generally does not encounter in othre fields. 

I think Sherlok Ohms would be recognize this as a good example of what it takes to solve a mystery.  You need logic, but also experience.

Stephen
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Gold
Re: Point and shoot
Stephen   12/20/2011 4:07:00 PM
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Shouldn't need adjustment as long as the antenna (and the structure/tower/building) remain in the same place and the satellite remains at the same geosyncronous point in orbit (or for the TV reception case the transmitter tower isn't moved). A moderate to severe earthquake may ruin your day aim wise if your near the fault, perhaps also hurricanes/tropical storms, etc. if a mast gets bent a little or a clamp slips), but continental drift shouldn't be a problem in your lifetime.

Not sure how well the stationaly geosyncronous birds do long term for orbital accuracy however -- there's another hardware system question to ask & understand. The higher the gain and narrower the beam angle, the more sensitive you'd be.

Rob Spiegel
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Re: Point and shoot
Rob Spiegel   12/20/2011 3:34:57 PM
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This solution makes me wonder whether the antenna will have to be adjusted over the course of time. Certainly that was true of TV antennas. Is this case, a constant signal may mean there will not be variation over time. Is that correct?

William K.
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Platinum
Satellite miscommunication.
William K.   12/20/2011 1:38:51 PM
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This story verifies that ancient piece of wisdom that "a chain is only as strong as it's weakest link". This certainly is applicable to systems that use antennas of any kind. OF course, knowing that already a bunch of well trained people had checked the rest of the system may have helped with recognizing the clues a bit.

Stephen
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Gold
Re: Point and shoot
Stephen   12/20/2011 9:33:02 AM
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Looks like it falls under understanding *all* the hardware, specificly high gain antenna gain plots.

Once you know highly directional high gain antenna designs have multiple relatively high gain lobes off the axis of the main (highest) gain lobe, then the possibility of a secondary lobe being aimed at the signal source leaving the highest gain main lobe pointed somewhere else leading to excessive S/N ratio becomes an obvious possibility.

Definitely a good real world example following an introduction to antenna gain plots in future teaching situations.

Alexander Wolfe
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Point and shoot
Alexander Wolfe   12/19/2011 6:48:40 PM
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Aiming the antenna correctly is definitely the correct way to maximize gain. Deft diagnosis. Holmes would be proud.

Rob Spiegel
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Re: Straight forward fix
Rob Spiegel   12/19/2011 3:29:52 PM
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You're right, Jenn. Usually the common sense solution doesn't come in until technology solutions have been exhausted. On this one however, I would think the simple solution would have been tried first, not last. Maybe that's just because I grew up having to move the antenna -- whether on the roof or on the TV -- in order to make things work -- like a decent TV picture.

TJ McDermott
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Maybe not so straight forward?
TJ McDermott   12/19/2011 2:49:03 PM
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Note the author said he'd erred years before with antenna pointing.  He had first-hand experience with the problem, and passed it on to his student as one thing to try.  I would hesitate to call this particular Sherlock Ohms straight forward, or requiring common sense.

Lauren Muskett
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Platinum
Re: Straight forward fix
Lauren Muskett   12/19/2011 1:50:59 PM
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Seems like a lot of training for such a simple solution. Sometimes the simplest solution is right in front of you. And I agree, it is great that the student was able to go and take care of the noisy channel. 

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