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Originally Posted by verder
This is interesting. Tablo support got back to me and indicated that the signal strength from my antenna may be too much for my Tablo. They recommended I turn my antenna away from the towers. I'm not entirely certain this is the correct course of action.
I asked if I could just put a splitter in-line to drop things if the signal is too strong. I went ahead and put in an Extreme BDS103H splitter with the -3.5dB output connected to the Tablo. I'm still receiving channels after performing a new scan so it didn't kill anything.
If that's not enough, and this truly is the problem, I can switch over to the -7dB port and see if that fixes things. I also have an Extreme BDS102H splitter that I assume I can daisy chain with the BDS103H for a max drop of -10.5dB.
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That IS interesting. How did they know how strong your signals are, did you give them a signal report?
https://www.rabbitears.info/searchma...tudy_id=143302
Turning the antenna away from the transmitter direction is one way to make signals weaker, but it tends to pick up multipath reflections which will increase errors. A better way is to use some type of an attenuator if you actually have signals too strong for a tuner. Longer coax or splitters will do fine.
WDAY RF 21, your strongest signal, would be the most likely signal to cause overload. But I never thought it would be a problem because you already have attenuation from the trees and the long coax when the antenna is outside. When the antenna is inside, you have even more attenuation.
A signal report is only a computer simulation which is often not very accurate, especially for 2Edge and Tropo signals. It assumes your antenna is in the clear, and doesn't account for coax loss.
So, it was a good idea to make the tests that you did to eliminate that possibility.
A rabbitears.info report lists a Signal Margin for a channel; it's similar to Noise Margin on a TVFool report.
Add the antenna gain and any preamp gain to the Signal Margin/Noise Margin when you look at the chart.
Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html
When you add an attenuator, it will make your strongest signal weaker, but it will also make your weakest signals even weaker by the same amount. If your weakest signals are already marginal, they could completely drop out.
When you have very strong signals and very weak signals, there is a great difference between the two. The difference between the strongest signal and the weakest signal is called the Dynamic Range, which is measured from the top of the strongest signal to the top of the weakest signal. To that, you must add 15 or 16 dB to allow for the necessary SNR of the weakest signal above the noise floor. This is called the SFDR (Spurious Free Dynamic Range.
Your goal is to make all the signals strong enough so that even the weakest can be decoded by the tuner, but not strong enough for the strongest signals to cause overload. Overload from two or more strong signals can create spurious signals from IMD (Intermodulation Distortion). The spurious signals will come up from the noise floor and reduce the SNR of the weakest signals.
