RG-59 & Amplifier? - Page 2

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Re: RG-59 & Amplifier?


Cable modems have an operating range (input signal level) of -15 to
+15dBmV  As long as your input level is within that range, it will work
just fine.  It's unlikely that you'll need to amplify that leg.  If
ingress is the cause of your problem, the cable modem may simply not be
heard above all of the other junk that's in there.

Another possibility is the splitter itself.  It could have gone south
and have more that the ~8dB loss that 4-way splitters have.

Unless not possible, a cable modem should always be on its own,
dedicated splitter (or DC) and be the first device in the line, after
the groundblock.


CIAO!

Ed

Crypt wrote:

> Also about the cable modem.  If I put the EDA-2100 before the cable modem
> (I'm thinking maybe where the cable line first comes in to the house) is
> there any chance it could help the cable modem maintain connectivity?
>
> Thanks!
>
>


Re: RG-59 & Amplifier?



> Hi all,
>
> I have cheap RG-59 cable running through the house.  (I'd say maybe 200ft
> total)  It is also split 4 ways with a 120db isolation 5-1000mhz splitter.
> The TV's and cable modem at the end of the cable have a lot of shadowing and
> other noise.  The cable modem also occasionally will lose it's connection.
> If I were to install a single port electroline 15db amplifier, would it
> resolve some of these issues?  I have read RG-59 cable is cheap and there
> are better cables, but I'd prefer not to re-wire the whole house if
> possible...

Shadowing is caused by poor impedance matching in the system.
There is somethig wrong between the signal source and the receiver.
Check the incoming signal quality. If ghosting is not in the
signal coming to your house, then the problem is in your in-house
wiring. You will need to correct that impedance matching problem
in the wiring. It maybe bad connection, damaged cable,
unterminated splitter output etc...
An amplifier will not help to get rid of ghosting!

Amplifier can help to get rid of some noise or redice
the effect of it. Amplifier needs to be installed
on the beginnign of your long cable and able to push
high enough signal levels to cable so that the signal
is still adequate on the other end.
Sometimes noise could be cauised by poor cable system
shielding picking up RFI.


--
Tomi Engdahl (http://www.iki.fi/then /)
Take a look at my electronics web links and documents at
http://www.epanorama.net /


Re: RG-59 & Amplifier?


The most common cause of ghosting is ingress, which is broadcast signals
leaking into the cable system.  By far, the most common cause of ingress
is the drop connector -- whether it be a cheap twist-on or push-on,
corroded, or just a little loose.  They all provide a pathway for a
broadcast signal to enter the system.  Then you have 2 (or more) out of
phase signals going to the tuner, which, of course, shows both(all).

The second leading cause is copper-braid cable.  It just doesn't provide
the shielding required.  Unlike a loose or corroded fitting where there
are just a few small points of ingress, ingress occurs the full length
of the cable.

Next on the list of causes of ingress are substandard passive devices
(splitters and DCs (taps)).  Splitters that just have the backs glued on
don't provide the shielding necessary.

Another cause of multiple images is unterminated outlets, which cause
reflections as well as being another source of ingress.

The return path of a cable system (5-42MHz) is VERY susceptible to
ingress.  If the CMTS can't hear the cable modem through all of the
noise resulting from ingress, it will lose sync.

The first thing you need to do is make sure that you have a clean system
in your house.  Cable with BONDED foil + aluminum braid (60% braid
coverage is fine),  quality connectors (preferably compression), and
splitters with a minimum 100dB RFI/EMI immunity.


CIAO!

Ed

Tomi Holger Engdahl wrote:
> Shadowing is caused by poor impedance matching in the system.
> There is somethig wrong between the signal source and the receiver.
> Check the incoming signal quality. If ghosting is not in the
> signal coming to your house, then the problem is in your in-house
> wiring. You will need to correct that impedance matching problem
> in the wiring. It maybe bad connection, damaged cable,
> unterminated splitter output etc...
> An amplifier will not help to get rid of ghosting!
>
> Amplifier can help to get rid of some noise or redice
> the effect of it. Amplifier needs to be installed
> on the beginnign of your long cable and able to push
> high enough signal levels to cable so that the signal
> is still adequate on the other end.
> Sometimes noise could be cauised by poor cable system
> shielding picking up RFI.
>
>


Re: RG-59 & Amplifier?


An excellent article on drops can be linked from
<http://www.cencom94.com/links.html .  Oddly enough, it's the one
entitled "Drops."


CIAO!

Ed


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