On Tue, 19 Dec 2006, Chuck Hast wrote:
> On 12/19/06, Eben King <eben01@verizon.net> wrote:
>> On Mon, 18 Dec 2006, Richard Smoot wrote:
>>
>> > 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.
Theoretical minimum is log10(1/2) bels = -0.301B = -3.01 dB for a two-port
splitter, and log10(1/3) bels = -0.477B = -4.77dB for a three-port splitter.
The pattern continues.
> 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.
Obviously these devices are not theoretically ideal, but hey, that's to be
expected.
> All of these devices have a low end frequency of 5Mhz.
What I was thinking was not a splitter but a crossover (like in a speaker,
but much higher frequency). But that would only work if data and TV
used different carrier frequencies.
-- -eben QebWenE01R@vTerYizUonI.nOetP http://royalty.no-ip.org:81 CANCER: The position of Jupiter says that you should spend the rest of the week face down in the mud. Try not to shove a roll of duct tape up your nose when taking your driver's test. -- Weird Al ----------------------------------------------------------------------- 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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