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[QUOTE=&quot;Rickideemus, post: 115295, member: 12677&quot;]Yes. The NM column is most pertinent. The power levels go through a little massage depending on whether the signal is analog or digital, and it comes out in NM, which stands for &quot;Noise Margin.&quot; The one thing you can add to NM is antenna gain (not amplifier gain). Then you subtract approximations for lost dB in the cable run and any splitting. If you have an amplifier, you run it through one of those amp calculators. You subtract a little more noise for the connections in the set itself. (Maybe another 3 dB? Depends on the set, I'm sure.) Theoretically, after you're done with all that, if the number is greater than zero, you can get a picture!But as you can see, there are many unknowns, like weather conditions, which way the wind is blowing through your trees, etc. etc. There are even different types of transmitters that might create wave forms more or less stable under different conditions (refraction, reflection, temperature flux ... who knows ... all hush hush ... very proprietary). You are catching everything right down to +19NM and then it stops cold. So that makes perfect sense. And you can see that either the trees are cutting out some signal, or the antenna is lower gain than we'd like. (Hard to find any solid gain figures on that type antenna. Maybe I'll hunt around the net tonight.)There are people with no obstructions like your trees who get signals with negative NM on the report. Not below minus 10 or so. Not unless you're like the guy who built custom Yagis cut to size for each individual frequency, then combined them with a half dozen A/B switches. :clown:Rick[/QUOTE]

[QUOTE="Rickideemus, post: 115295, member: 12677"]Yes. The NM column is most pertinent. The power levels go through a little massage depending on whether the signal is analog or digital, and it comes out in NM, which stands for "Noise Margin." The one thing you can add to NM is antenna gain (not amplifier gain). Then you subtract approximations for lost dB in the cable run and any splitting. If you have an amplifier, you run it through one of those amp calculators. You subtract a little more noise for the connections in the set itself. (Maybe another 3 dB? Depends on the set, I'm sure.) Theoretically, after you're done with all that, if the number is greater than zero, you can get a picture! But as you can see, there are many unknowns, like weather conditions, which way the wind is blowing through your trees, etc. etc. There are even different types of transmitters that might create wave forms more or less stable under different conditions (refraction, reflection, temperature flux ... who knows ... all hush hush ... very proprietary). You are catching everything right down to +19NM and then it stops cold. So that makes perfect sense. And you can see that either the trees are cutting out some signal, or the antenna is lower gain than we'd like. (Hard to find any solid gain figures on that type antenna. Maybe I'll hunt around the net tonight.) There [B][I]are[/I][/B] people with no obstructions like your trees who get signals with negative NM on the report. Not below minus 10 or so. Not unless you're like the guy who built custom Yagis cut to size for each individual frequency, then combined them with a half dozen A/B switches. :clown: Rick[/QUOTE]

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