nrc said:
...WBNS 21 has frequent dropouts and breakup. Worse during the day and getting better through the night.
This is puzzling because as you can see it's the exact same direction and distance as WCMH 14 and that comes in perfectly. Both show about a 92 on signal strength but during periods of breakup the WBNS signal drops into the 40s for brief periods.
The provided antenna is a DB2. Based on some reports that the HD Tivo's receiver is easily over-driven I tried putting a 6db attenuator in the line with no affect...The only other thing I can think of is maybe a more directional antenna if it's multipath. The DB2 has a 90 beam width so I may try turning it a bit to see if I can get the multipath source out of the beam and still keep a good signal..
The DB8 and 4228 are both more directional, I would try the 4228. Realize that some of these channels are off axis, so more directionality might get you CBS, but might also degrade some of those.
Before you do that, I would try an amp. I, too, was alerted to the potential overload problem of the HR10, but adding a 25 dB amp and cranking it up all the way (from 12 miles out) just to see if I could overload my two HR10s resulted in that NOT happening, so maybe the overload issue is overblown. It might be a good thing to check for the power output (also on antennaweb.org) to see if the power of the CBS station is lower than the other one you are receiving from that axis. If so, the amp might be a good move, and it might be regardless.
This thread documents a procedure that might help you with that:
http://www.tivocommunity.com/tivo-vb/showthread.php?t=275316
Two stations of
different output power can easily measure the exact same signal quality. If you are getting all of the bits from both, 92 would seem like a reasonable reading, regardless of the power output level differences. When just one of them drops to 40, that may indicate multipath or it may indicate that you are just on the threshold, level-wise, for the lower-powered one.
Now, when atmospheric or other conditions puts one on the threshold while the other is still just above the threshold though also weakened, the weaker one can drop precipitously (in signal quality reading) while the other signal, even though weaker, doesn't drop
in signal quality readings at all, because you are still receiving all bits uncorrupted (though at a lower level) from that signal. I know, it makes my brain hurt, too. But that's the physics involved there.
On the other hand, if the signal swings wildly, that may indicate threshold reception (meaning an amp could help) or it could also mean multipath (meaning a more-directional antenna could help).