Cable Splitting (-7db vs. -3.5db)
PostMaster
splitter. 2 of the outputs are listed as -7db (1 going to analog tv
in
bedroom and the other -7db to modem [30mb service at that time]. The
-3.5db to the HDTV in living room. I have my doubts that it was done
correctly to begin with.
I have a couple of different questions on the subject. Which is the
stronger signal and how would it be best to break it down to 4
outputs? If I split a -3.5db would it make two -7db or would
splitting
-7db make two -3.5db? Which is stronger? What is sufficient? I know
what a decibel is relating to sound but I have no idea how it relates
to data transfer speed. If someone could briefly explain the
difference.
I want most of my bandwidth to go to my modem and my HDbox in living
room. The other 2 outputs I'm just using 2-99ch analog. As it stands
now my internet connection doesn't seem to perform as well as it
could
and I get some occasional freezing on my HD signal. Everything in my
hard wired network checks out fine. I have checked all connections
inside and I am using high quality cable. I also had the cable
company
come out and check the line outside and they even installed a new
lock
box. I am also concidering an inline booster, or even a powered one
if
it would make a noticable difference.
If there is anyone with an electronics degree out there that could
show me the light I would be most grateful.
I basically just want to make sure I'm doing everything from the wall
to the devices as efficiently as I can possibly do it.
thanks,
pm
PostMaster
> On Thu, 24 Mar 2011 18:06:52 -0700 (PDT), PostMaster
>
>
>
>
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> <ngpos...@yahoo.com> wrote:
> > When my cable was originally installed they hooked it up to a 3 way
> >splitter. 2 of the outputs are listed as -7db (1 going to analog tv
> >in
> >bedroom and the other -7db to modem [30mb service at that time]. The
> >-3.5db to the HDTV in living room. I have my doubts that it was done
> >correctly to begin with.
>
> > I have a couple of different questions on the subject. Which is the
> >stronger signal and how would it be best to break it down to 4
> >outputs? If I split a -3.5db would it make two -7db or would
> >splitting
> >-7db make two -3.5db? Which is stronger? What is sufficient? I know
> >what a decibel is relating to sound but I have no idea how it relates
> >to data transfer speed. If someone could briefly explain the
> >difference.
>
> a -3.5dB signal in half, each half is approximately -7dB.
>
> TV's are usually pretty forgiving of signal strength and are able to
> work over a wide range. Some TV's have an on-screen signal strength
> meter, sometimes available via the Info button on the remote. Those
> meters aren't calibrated or standardized in any way, but they can give
> you a rough idea of where your signal levels stand.
>
> Cable modems, on the other hand, are usually specified to work over a
> range of +15db to -15db, and because signal levels can fluctuate over
> time due to various external factors, some people like to play it a
> bit safer and want their cable modem to work within a range of +10dB
> to -10db.
>
> There is no relationship between signal strength and data transfer
> speed, assuming the modem is working with an acceptable signal. Many
> modems have an internal web server that will show you, among other
> things, your Upstream and Downstream signal levels and your Downstream
> Signal-to-Noise Ratio. Try browsing tohttp://192.168.100.1
>
> You might want to draw a map of your entire cable network, showing the
> incoming cable, each splitter (and its effect on the signal), ending
> with each TV or modem. For planning purposes, assume the incoming
> cable has a signal strength of 0dB, then just subtract 3.5dB for each
> leg of a 2-way splitter or subtract 7dB for each leg of a 4-way
> splitter. 3-way splitters can either be balanced, (the same amount of
> loss on each leg), or unbalanced, (-3.5dB on one leg and -7dB on the
> other two legs). The unbalanced type is more common, and is
> essentially a 2-way splitter with one output leg feeding into a second
> 2-way splitter. Likewise, a 4-way splitter can be thought of as a
> 2-way splitter with each leg feeding an additional 2-way splitter.
>
> Once you've drawn the map and have taken all splitters, amps (if
> applicable), and your cable modem's signal level into consideration,
> you're ready to decide if changes need to be made. Changes could be as
> simple as rearranging your existing splitters, combining multiple
> splitters into fewer splitters, asking the cable company to adjust the
> level of your incoming signal, or as a last resort, adding a 'drop
> amp'.
>
> --
> Bill
You pretty much gave me all the info I need to achieve my goal.
Much Thanks.
PM