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By Noel Lee
Anyone who's ever had to suffer through
poor TV reception knows exactly what interference looks like. Stray signals and
electromagnetic waves can sneak their way into your audio and video gear,
degrading both the picture and the sound. It is virtually impossible to stop
interference at the source because it comes from everywhere: from the hundreds
of different radio transmitters that probably operate within close range of your
home (unless you live in rural North Dakota, of course), to the dimmer switches
in your house, to your telephone, your neighbor's electric razor, and even the
sun. Interference can occur at very low frequencies, at very high frequencies,
and everywhere in between. And most of the interference that enters your A/V
system comes in through the cables, which often act just like antennas for
interference. That is, unless you choose cables designed to combat interference
in the first place.
Interference is a big problem for cables that
carry low-level signals like audio interconnects; for composite video cables
that carry signals from your VCR, DVD player, and camcorder; and for video from
antennas, cable TV, and satellite receivers. Most audio interconnects and video
cables have shields, which are a metal covering that surrounds the inner
conductor of the cable. In order to be effective, the shield must be grounded,
so that any interference that strikes the shield is safely conducted away to
ground before it can reach the sensitive inner conductor. All shields aren't
created equal, though. Preventing interference in high-frequency video signals
is quite a different matter from preventing interference in an audio cable,
which carries low frequencies. Each places its own demands on the shielding used
in the cable.
For Monster Video® cables, we employ two
separate shields. First, there's a braided copper shield that covers 95% of the
cable's surface area. Because of its high density, the braid provides excellent
protection against the relatively long-wavelength, low-frequency types of
interference, like AC power hum and interference from electrical appliances. The
braided copper strands are both very flexible and durable, and the copper
provides conductivity that's far superior to what you get with cheaper aluminum-
and steel-wire shields.
However, the short-wavelength, high frequency
interference that's so detrimental to video signals can sneak through a braided
shield. That's why we add an aluminum foil shield, which provides 100% coverage
and even keeps stray very high-frequency signals from passing through to the
center conductor. We also overlap the foil shield, so that it doesn't gap open
when you bend the cable. For running in-wall video cable over long lengths, we
even offer a UL-approved cable with quadruple shielding-du-A foil and dual
high-density braiding for maximum protection against interference.
Many lesser cables use spiral shields, which are
made by simply winding thin strands of wire around the center conductor's
insulation. Spiral shields often have gaps that permit high-frequency
interference to pass right through to the center conductor, and they also create
inductance, which can filter out the high-frequency content of your video signal
and rob your picture of its fine detail.
So if you notice wavy lines or noise in your TV
picture, it's time to switch to a better cable. Using Monster Video® cables
will minimize interference and give you every ounce of performance your system
can dish out.
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