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Wildly fluctuating signal strength

462 Views 6 Replies 6 Participants Last post by  Kipp Jones
After hooking up my Zenith HD-SAT520, I discovered that my OTA DTV reception comes and goes. Looking at the signal-strength meter, I see extreme fluctuations, from almost good to no signal, within spans of less than a minute. There's no pattern--sometimes it's good for a few minutes running, sometimes it is constantly going in and out of lock. Any idea what might cause this?

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Post your experience in the HD Local Info and Reception forum. Make sure to post your location in the title and your box and antenna type in the text. It could be that others are in your situation and have found a solution. The most important moves include using a highly directional antenna and getting it outside the house. Of course its not impossible that you have a bad STB.
MDRiggs: As has been pointed out, multi-path is the likely cause of the fluctuations is the signal to noise ratio you report. Often, the relocation of the antenna just a few feet or even inches from side to side and/or up and down can help stabilize the signal. If you know someone with a meter to measure OTA antenna signals, the you are in business. IF not, then a trial and error method can yield good results.

Also, tilting the antenna with the front end pointed up may help.

However, without a meter, you are just guessing. I have seen many friends installs that "looked" to be in the best location, but when checked out an less apparent location proves to be the best.

A field strength meter probably won't help as much in this circumstance as the tuner's own signal strength indicator. A field strength meter adds the direct path signal with the multipath signal without distinguishing between the two.

Often, the most stable performance in a harsh multipath environment comes from pointing a highly directional antenna somewhat off-target, as the signal-to-noise ratio can sometimes be maximized by orienting the antenna such that the "null" in its reception pattern is most directly pointed at the undesired multipath signal's direction. On a conventional field strength meter, the signal strength level would be lower because the direct path signal might be down a few dB, but the multipath contribution to the total signal strength might be weakened even more.
How stable is your antenna mast? I have seen where under certain conditions, slight movement will cause what you are describing.
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