Keep in mind that the concept of the Noise Margin (NM) is a construct to help understand the probabilities of reception, it's a very useful tool in analyzing the possibilities for reception. It is not the definitive answer as to whether reception is possible or not due to its theoretical nature and the various assumptions that have gone into the calculation. Only installing a real antenna system will provide that definitive result.
I always recommend an appropriate pre-amp when very weak signals are involved, unless there are excluding circumstances, simply because it does indeed improve the system noise figure and, consequently, the "fade margin".
The tower listed for Forsyth is the KWBM tower. According to data on rabbitears.info recorded on 10/27/15, it was broadcasting KRBK's primary programming as one of its only sub-channel with Daystar as its primary feed. It does not broadcast the two additional subs carried on KRBK's own DTS system.
I did notice an incorrect assumption in post #2:
Quote:
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K26GS, -33.3 dBm Signal Pwr + antenna gain 14 dB = -19.3 dBm, OVERLOAD
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It is necessary to use the gain (in dBd) at the reception angle, not the straight ahead peak gain. Assuming the UHF antenna is aimed due north, the amount of realized gain at ~75° off to the side is the correct number to use in that equation.
