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I've been having intermittent interference with my cable picture (where analog channels get streaky interference, and HDTV channels drop out totally). My cable company (TWC) was good enough to come work on it today and replaced some old connections. They also installed a "noise filter" or "noise suppressor". It was a cylindrical device, looked about the size of a "D" battery. What does a "noise filter" like this actually do? Does it only pass a certain range of frequencies? Does it do something to stabilize the signal? Just curious if any techs with experience know how it works.


After everthing was done, I'm not positive, but I think my picture on analog channels looks a little softer (less sharp and less contrasty) now. Could the noise filter actually cause a reduction in picture resolution or contrast or does it operate on different principles?
 

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As you suspected, this noise filter is just a high pass filter, that will remove the lower frequencies, where noise is usually inserted into the RF spectrum from external interference.


This would not have an effect on the picture unless it dropped the signal strength by a dBmv or two. These should be passive for the most part however, so I doubt it is inhibiting your signal.
 

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I think you are just seeing things...


There is no way (that I know of) to make an analog picture not as sharp or contrasty - it would just introduce noise/snow if it had problems.


Have you checked your TV settings? The tech may have changed sharpness/etc if they were set too high (or to hide a slightly fuzzy picture)
 
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