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Old 5-Jun-2012, 5:02 PM   #1
gossamer
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Disparity between TVFool and AntennaWeb for CBS-NY

Hi all,

If you've been following my antenna saga, I have a Winegard HD7694P here in northern NJ. Most stations are very good, but there's a quality tradeoff between CBS and FOX. I've settled on about about 140 degrees to get the best balance between CBS, which is apparently northeast of me, and the rest, which are southeast.

My question is that antennaweb says it's at the same 156 degrees as all the other channels, but TVFool says it's more like 45 degrees. Here's the graphs:

# AntennaWeb layout
http://www.antennaweb.org/Stations.a...Lon=-74.131947

# TV Fool channel layout
http://www.tvfool.com/?option=com_wr...b1a86fc29cfc1d

Why the disparity?

Is there indeed a CBS that's also southeast?

Thanks,
Dave
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Old 5-Jun-2012, 5:14 PM   #2
ADTech
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WCBS is on the ESB in New York city, same as everyone else of import.

If you're looking at WFSB, it's out of range (Hartford, CT).

If you're having problems with one of the ESB stations while receiving the rest, relocate your antenna. You're likely getting a frequency-specific reflection (multi-path).
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Last edited by ADTech; 5-Jun-2012 at 6:59 PM.
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Old 5-Jun-2012, 6:09 PM   #3
gossamer
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Quote:
Originally Posted by ADTech View Post
WCBS is on the ESB in New York city, same as everyone else of import.

If you're looking at WFSB, it's out of range (Hartford, CT).

If you're having problems with one of the ESB stations while receiving the rest, relocate your antenna. you're likely getting a frequency-specific reflection (multi-path).
I'm still a little confused. In the TVFool graph, Real 33, which is says is WCBS-DT, appears to be northeast.

There's a WCBS-TV near the bottom of the list. Is that the one I should be referring to?

Is the frequency-specific reflection you're talking about the "co-channel warning" indicated in the graph? Otherwise I don't understand what you mean by frequency-specific reflection.

Thanks,
Dave
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Old 5-Jun-2012, 6:49 PM   #4
ADTech
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WCBS is near the TOP of the list, position # 6. WFSB is near the bottom, 4th from the end of the list. Both stations operate on UHF channel 33, hence the co-channel warning to the left of the WFSB entry which would indicate it would be completely eclipsed by the much more powerful WCBS.

Even though multiple signals may originate from the exact same antenna as is done on the ESB, each signal may may travel a slightly different path by the time it arrives at your location. Because of the varying wavelengths of the signals, only a certain frequency or small range of frequencies may bounce off some physical object (building, structure, tree, hill, etc) near the signal path such that the reflection arrives out of phase with the original signal. Such reflected signals will add or subtract from the primary signal so that the resultant signal might be anywhere from twice as large (completely additive) to zero (cancels completely). because the ATSC sinal is more than 5 MHz wide, it doesn't take a great deal of reflected energy to cause a hole in the received signal and the data is corrupted. The tuner has to figure out if it can equalize the difference and, if it is unsuccessful, will loose the ability to decode the digital information in the signal. This will cause the dreaded "Weak or no signal message" regardless of the actual signal power at the tuner input.

In the absence of a spectrum analyzer, about all you can do is to move the antenna and try again.
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Last edited by ADTech; 5-Jun-2012 at 7:00 PM.
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Old 6-Jun-2012, 12:22 AM   #5
gossamer
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Quote:
Originally Posted by ADTech View Post
WCBS is near the TOP of the list, position # 6. WFSB is near the bottom, 4th from the end of the list. Both stations operate on UHF channel 33, hence the co-channel warning to the left of the WFSB entry which would indicate it would be completely eclipsed by the much more powerful WCBS.

Even though multiple signals may originate from the exact same antenna as is done on the ESB, each signal may may travel a slightly different path by the time it arrives at your location. Because of the varying wavelengths of the signals, only a certain frequency or small range of frequencies may bounce off some physical object (building, structure, tree, hill, etc) near the signal path such that the reflection arrives out of phase with the original signal. Such reflected signals will add or subtract from the primary signal so that the resultant signal might be anywhere from twice as large (completely additive) to zero (cancels completely). because the ATSC sinal is more than 5 MHz wide, it doesn't take a great deal of reflected energy to cause a hole in the received signal and the data is corrupted. The tuner has to figure out if it can equalize the difference and, if it is unsuccessful, will loose the ability to decode the digital information in the signal. This will cause the dreaded "Weak or no signal message" regardless of the actual signal power at the tuner input.

In the absence of a spectrum analyzer, about all you can do is to move the antenna and try again.
I understand what you wrote completely. Thanks so much for the explanation.

Thanks,
Dave
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