On 12/19/06, Eben King <eben01@verizon.net> wrote:
> On Mon, 18 Dec 2006, Richard Smoot wrote:
>
> > On Monday 18 December 2006 09:56, Chuck Hast wrote:
> >> I can send you a picture of my installation, the cable comes through the
> >> wall from the cable box with the lightning protection, and hits a 2 port
> >> splitter, one port goes to the TV's in the house and thier splitter, the
> >> other port goes to the modem. And as Robert said use RG6QS, and the good
> >> connectors, and the correct splitter, it also needs to be bi-directional,
> >> and should pass from 5 Mhz up. If I recall my cable technolog corretly the
> >> bearer signal is in the spectrum from 5MHz upt to 49Mhz or there abouts,
> >> and your splitters need to handle the spectrum flow both directions, and
> >> they need to handle the low end frequencies correctly or you will have
> >> problems on the return leg of your data link. I will send you a picture of
> >> my setup, I have the modem routers and hubs in the garage, all to where I
> >> can recycle the stuff and keep on going. If I need to check things out I
> >> just roll up a small table and put the laptop on it and plug into a open
> >> port and start poking.
> >>
> >> As someone else pointed out you can use WiFi and cut the wires... That is
> >> how I have things set up at the house, I do have some cable in the walls
> >> but do not use it right now just the wifi cards.
> > Who is your provider? My connection comes from the street to a fairly good
> > size box outside the house. The cables for TV and the Cable modem come
> > into my house to differant rooms. The cable modem connection is exclusively
> > meant for it. No splitters or amplifiers should be used on that connection.
> > Never attach a TV to it.
> > If you are talking about the TV cable connections, the frequencies involved
> > start somewhere above 49mhz and go up to somewhere around 800mhz.
>
> And I think they're different frequencies, so there shouldn't be any loss by
> an (ideal) splitter. Any splitters for extra TVs should be placed _after_
> this.
>
> Caveat: I've never been a CATV installer. I don't even play one on TV.
>
The splitters are not frequency selective in the sense that the are designed to
pass certain bands and block others, they have a passband and that is it.
What they do is split power and put it on each port, so say a -20 dbm
signal on the input is now a -40 dbm signal on each port if the splitter has
a 3db reduction in power to each port. This is why you want good splitters
that do not have too much loss, I think that most of them are like 3.5 to 4.5
port, and several of them do specify the loss based on spectrum, the higher
the frequency the greater the loss. So on the low end you will see about 3.5db/
port and on the high end about 4.5db/port. A 3 port splitter will have 5.7 db
/port on the low end and about 2 db more loss on the high end. and a 4 port will
have about 7.5bd/port on the low end and about 9.5 on the high end, the high
end for these devices in this case being 2.4Ghz. If it is a 1Ghz high
end it will
not be quite as bad. All of these devices have a low end frequency of 5Mhz.
Also if you do insert a amplifier in the line and it is between your cable and
your cable mode/tv's make sure it is bi-directional, the modem has to send
as well as receive.
-- Chuck Hast -- KP4DJT -- To paraphrase my flight instructor; "the only dumb question is the one you DID NOT ask resulting in my going out and having to identify your bits and pieces in the midst of torn and twisted metal." ----------------------------------------------------------------------- This list is provided as an unmoderated internet service by Networked Knowledge Systems (NKS). Views and opinions expressed in messages posted are those of the author and do not necessarily reflect the official policy or position of NKS or any of its employees.
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