TiVo Community Forum Archive 1

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Posted by ShiningBengal on 06-29-2004 07:15 AM:

quote:
Originally posted by aaronwt
The pipes in these condos are not metal. The main line going to the water meter for the building isn't metal either.


Holy horsepucky! I've heard of non-metallic water mains, but I hever thought anyone actually used them!

Seriously, though, regardless of where it originated, you almost certainly have a ground loop somewhere in your system.

A ground loop generates noise in A/V equipment by in effect, acting as both a coil and an antenna. The coil can pick up magnetic variations in power equipment--such as a tranformer, or even an air conditioning compressor. It can also act as an antenna, picking up radio frequency signals and amplifying them. The type of video noise you see on your monitor is very strong evidence of these signals being present within the ground loop.

With cable TV, or CATV systems, you can use an inline device called a "ground breaker" which introduces a small gap in the shield of the cable, breaking the current path but leaving the RF carrying capabilities intact. But you can't do that with satellite systems, since the cable must carry a DC voltage from the receiver back to the LNB to switch polarities as the receiver requires this to receive a particular channel. The gap in a ground breaker makes this impossible.

Just be glad you found a way to get rid of the effects. Ground loops can be very difficult to resolve satisfactorily.

__________________
"Ignore 'em, m'dear. They're beneath your dignity." W.C. Fields


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