Amplification (also known as dB boost): Amplification is the
process of boosting a signal. Amplification is generally needed for homes with multiple
TVs, or where long cable runs are used. Amplification is generally a good
thing, except for the fact that cheap TV amplifiers don't do a real good job, and can
actually make the TV signal worse. Cheap amplifiers add "noise" to the signal,
which can then be seen as ghosts, buzzing, snow, lines through the picture, and other
annoying things. Good amplifiers do their job so well that they don't add ANY noticeable
noise to the TV signal. Good amplifiers make your picture look BETTER, and don't cause
side effects like ghosts, lines, or snow. The boost is measured in dB.
Bi-Directional: Bi-directional means
that signals can pass in both directions. This means that the cable company can send
signals to you, but you can also send signals back to the cable company. Bi-directional
has nothing to do with Amplification. Cable signals can be amplified in one
direction only, by ONE amplifier. If an amplifier is advertised as amplifying in BOTH
directions, be aware that these products are extremely uncommon. To amplify in
the return direction, you need a Return Path Amplifier.
Bi-directional amplifiers are the kind that you typically do NOT find on the store
shelves, even at your favorite video/electronics store. These amplifiers are different
from the cheapie amplifiers for a number of reasons. First, they are generally made of higher
quality components. Electroline amplifiers are NOT made in China, although many
other brands are. Bi-directional amplifiers
use expensive, high tech components which allow them to amplify the TV signal, and at the
same time allow your cable box to send signals back to the Cable Company. Bi-directional
amplifiers operate in the 50-1000 MHz range, making them PERFECT for
Standard Cable, Digital Cable, interactive services and Cable Modems. Bi-directional
amplifiers only amplify the signal going TOWARD your TV or Cable box. They DO NOT amplify
signals going back to the cable company, and for that reason they may not always work well
with cable modems. Only 1-port or 2-port amplifiers should be used with cable modems
for the best results.
Cable Modem: A Cable modem is a
piece of equipment which receives data from your cable company (your Internet
provider) and also sends data from your home back to the cable company out onto the
Internet. It is always used with your home computer. Cable modems allow you to send
information to and from the internet just like a regular modem, except you use the
cable company's cable lines instead of the phone company's phone lines. Cable
the same signals as your regular cable TV converter box. The only difference is that the
cable modems use different frequencies which cannot be seen by your television set. Cable
modems generally require a pretty strong signal, which also means that they require a
fairly unrestricted path back to the cable company. This is why the cable company will put
in a totally separate cable connection dedicated to the cable modem. Cable
GENERALLY work in conjunction with a Bi-directional amplifier or splitter as
long as the path back to the cable company is not blocked.
Depending on the specific situation, a bi-directional amplifier may improve or degrade your cable
modem performance. The best rule here is " If it ain't broke, don't break
it". If your cable modem is fast and generally reliable, you don't need an amplifier
for it. However you might still need an amplifier for the rest of your TV equipment in the
dB : TV signals are actually measured in dBmVs. A dBmV
is a somewhat complicated to understand reference voltage term used in the TV/Cable
industry. In a nutshell, TV signals are transmitted using extremely low voltages (around
1/1000 of 1 volt) of electricity on your cable lines, and what the actual voltages are
determines a lot about how your TV picture will look. No, you don't need to understand dBmVs,
but you might want to understand how splitters and amplifiers affect your TV signal,
and that is where we talk about dBs. dBs are a RELATIVE measure of
how strong your signal is, versus how strong/weak it USED to be.
F Connector: An F Connector is the screw-on connector used on the back of your TV, VCR, or
cable box. It is a
standard for all TVs, VCRs, and cable boxes. When replacing cable ends or installing new cables, always use high
quality crimp cable connectors. There are different sizes for RG59, RG6, and RG6-quad
so be sure to obtain the right ones.
Frequency Range/Bandwidth: The
frequency range (bandwidth) determines what range of signals an amplifier can handle.
Basic outdoor Antenna TV and Cable TV signals go from 50~800MHz (MegaHertz), Digital Cable
services can go as high as 1000MHz (also known as 1 Gigahertz - GHz). Digital Cable and
Cable Converter boxes also require what is called a return path. Cable
amplifiers do not provide a return path unless they explicitly advertise that they do. If
the amplifier does not support a 5-42 MHz return path, it will not work properly
with cable boxes
or cable modems.
4-port and 8-port Electroline amplifiers come in two versions - those WITH forward gain,
and those with UNITY gain. The Unity Gain amplifiers generally have the letters
"UG" right on the label (EDA-UG2402
or EDA-UG2802). A unity gain amplifier acts just like a big splitter. It breaks up a
cable signal, but does not provide a boost to the signal. This means that "signal
strength IN = signal strength OUT". Unity Gain amplifiers are generally used for
special applications where you specifically do NOT want any amplification of the signal.
Standard amplifiers will provide forward gain, which is expressed as a dB number. 4-port
amplifiers generally provide 7dB of "forward gain", and 8-port amplifiers
generally provide 4dB of "forward gain".
Forward Path Equalizing (Tilt)
Amplifiers: Equalizing Amplifiers come in only 1-port versions. They are
specialized equipment designed to overcome some of the problems associated with very long
cable runs. When a cable signal travels over a long cable run (>150 feet), the higher
channel (high-band) signals tend to lose strength faster than the lower channel
(standard-band) signals. If you use standard amplifiers over long cable runs, you end up
with very strong standard-band signals (low channels), and very weak high-band
signals (high channels). Essentially you
will be able to see the lower channels, but the higher channels may be weak. The opposite
may also happen: the standard-band signals may be so strong that they OVERDRIVE your TV or
cable box, and the high-band channels may be just fine. The solution to this problem is to
install an equalizer over long cable runs. The Electroline
EDA-EQ3100 boosts the signal more on some channels than others, so that this
"long cable run" problem does not occur.
Return Loss (dB): Every time you
put a splitter or amplifier into your cable line, it causes the signals going BACK to the
cable company to weaken. This is particularly problematic if you are using a cable modem
or Digital Cable Services. If the signal that the cable modem or Digital Converter sends
back to the cable company is too weak, your services may not work. Each splitter or
amplifier is rated for (return) loss, which basically tells you how much signal strength
you lose when the signal goes back through the splitter or amplifier. If a
splitter is marked with "3.5 dB", that means you
lose 3.5dB of signal, or about 56%.
Return Path: The Return Path
is a special frequency range used by the cable company to transmit signals FROM your cable
box BACK TO the cable company. Ever wonder how the cable company can allow you to
"talk back" using your cable TV box? How about ordering a Pay-Per-View special
using your cable box remote control? The cable TV boxes actually transmit signals BACK to
the cable company to tell them that you want to watch the "Wrestlemania"
pay-per-view event. Then the cable company sends a signal back to your cable box to
"turn on" the pay-per-view channel. That's how they do it. Cable companies also
require the return band for use with cable modems. If the cable amplifier does not support
the return band, the cable modem won't work. The standard return path is in the
5-42 MHz frequency range. A bi-directional amplifier is required to allow these special
cable company signals to travel back to the cable company. CHEAPIE amplifiers will not
work with Cable TV Digital services, Multimedia (Cable Modems), and Cable TV boxes.
Return Path (Reverse)
Return Path (Reverse) amplifiers are almost the opposite of the description above, as they
amplify ONLY the 5-42 MHz (return band) signals going back to the cable company. A Reverse Path
amplifier will help in situations where the RETURN traffic going back to the cable company
needs to be boosted, or where the digital cable box or cable modem is unable to consistently transmit
information back to the cable company. Usually this is because of long cable runs which
tend to decrease the signal significantly.
RG6, RG59: These terms describe the
physical cable used to carry cable signals throughout your home. RG59 is thinner and cheaper, and allows more
signal loss. RG6 is a heavier cable which comes in 2 flavors - standard and
quad-shield. If you are installing new cables in your house, use quad-shield cable.
costs about 20-30% more than regular RG6, but keeps SIGNAL LOSS at a bare minimum. You
should not use RG59 cable unless RG6 is unavailable. Home Depot carries both
RG6 and RG6 quad-shield cabling in 100 and 500 foot spools.
Splitter: Splitters are used
to break your incoming cable or antenna signal up so that it can go to more than one
TV or cable box.
Everyone has at least one splitter somewhere. The problem with splitters is that every
time you use one, you cut your signal strength down. It's like putting one of those
Y-splitter things on your garden hose. You never seem to get enough water
pressure (signal strength) after you do that. These drops in strength are also measured in
A high quality two way splitter will generally make you lose 3.5dB. A 4-way splitter will make you lose at least 7dB of signal
strength. What does that mean? Well if your signal drops enough, you will get snow or a
fuzzy picture. If you use multiple splitters, you actually degrade your TV signals
Splitters also have a Frequency Range. Always use high quality, 1000 MHz DC PASSING
splitters. If you use high quality splitters you will save yourself a lot of headaches.
They cost more, but they are worth it. cableTVamps.com only sells these high quality
1000 MHz splitters.
Signal Strength Lost