Interference problem

[Neutrino Tau]

Ok, let me go over all the basic info first. I live in zip code 30677, but in the northwestern extent. The house is situated on a hill and from looking at
a 5ft contour i can't see any problematic hills in the general area. I can provide the extra 4 digits of the zip or gps or UTM or StatePlane coordinates for
my location to a pro if necessary (i'm a gis student, i can provide most any locational info you might want). The antenna is a Channel Master 3020, the HD
tuner is a Zenith, not sure of the model but it was one of the first Digital recievers on the market, tv is a HDready so it didn't have the tuner. The
antenna is clear of the roof line and about 30ft above ground and as I said this is one of the higher points of the county. Antenna web classifes us as Deep Fringe and we are about 57 miles from Atlanta.

Now for the problem. The issue is that we've gotten for a few hours at a time, 11 of the commercial atlanta station(i'm including gpb(wgtv)) in digital
television. This includes pba which is our weakest channel and we've gotten it reliably. The key, though, is that it's been only a few hours at a time and
at most 10 times a year. Here is my key problem, those glorious periods of great reception end instantly when a souce of interference switches on. as
quickly as turning on a light switch, all of the channels drop by as much as half the signal meter. the strong channels (wxia, waga, gpb) drop to ~60-70%
(30% requirement for picture) and the rest drop to borderline and pba drops from 40% to nothing. The problem is that I have no idea where or what the
interference could be, it hits everything from wsb-DT on 39 to wsb analog on 2. As far as direction, it seems to drop off as I aim away from atlanta but it
could easily be some other effect. One curious aspect of the interference which may be from the main source or a second one, it seems to be cyclic in
nature; as in on analog television it wavers in and out. On both 2 and 46 analog, I've been able to notice a fast cycle (2-5 sec per cycle) and a slow cycle
(1-2min per cycle) in which the static in the picture reaches peak and then drops and then peaks again. As far as possible sources, a popular athens radio station (10X.X FM don't remember the exact frequency) has an antenna due north of our location, there is an unknown tall antenna in the general direction of atlanta, our line of sight of atlanta goes over winder-barrow airport (if radar would do the cycle) and there are cell towers all over the area.

My question after all of that info is what can be done, the antenna seems strong enough and everytime we've tried an amp, all the channels die on digital, due to overly strong signal. I'm curious if something like the antennas direct 91XG or something similar might be focused enough to pickup just the signals we want? The current antenna seems to pick up channels fairly well at 90 degrees left or right of the intended yagi focus and only blocks well at 45/135 off to either side.

PS:Sorry about the long post but i'm trying to throw in all significant items I've found from 3-5 years of dealing with this issue.

[hdtvlabs]

I have no idea where the mysterious interference is coming from in your case, but here are few points you should be aware of when dealing with interference. Check them in the order listed below.

1. Move your home appliances away from the antenna, the TV and the cables. Cyclic interference that you describe may be a result of electric devices switching on/off automatically, i.e an air conditioner or a heating system (that goes on and off by a thermostat)

2. Use a good coax

3. Use a directional antenna with a good F/B ratio. This way you will attenuate any interference that is not coming from the direction of the signal.

4. Limit your antenna bandwidth to the minimum. For instance, if all your channels are in the UHF band, use a UHF-only antenna.

If the interference source is not in your house, and it is coming from the direction of the TV towers, and it is in the same frequency band as your channels, then .... there is nothing you can do.

Hope this helps.