How many is too many Cable TV outlets?
INVALID ADDRESS: Use only REPLY-TO address
I'm remodeling my old house. I figured that since I have the
drywall removed from the walls and ceiling, that I should add
extra cable TV and phone outlets. I assume that each time the
cable is split up to go to each outlet, the signal strength is
lowered. I would like to add a new outlet to each wall (or at
least every other wall) in 3 or four rooms. What's the best
way to wire this and how do you prevent signal loss. I'm talking
about 10 or more outlets in the whole house. Same goes for the
phone outlets. Of course I won't be using all of them at the same
time, but I want the options of hooking up 2 or 3 TVs and phones
and being able to change their locations without running a new
cable every time.
Please post or email me by removing *NOSPAM* from my address.
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Reply only to edwarwd@*NOSPAM*mail.auburn.edu
NOTICE: Mail sent to the FROM address will be bounced.
J.P. Boileau
On Fri, 30 Jan 1998 11:15, CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID
ADDRESS: Use only REPLY-TO address) wrote:
>I'm remodeling my old house. I figured that since I have the
>drywall removed from the walls and ceiling, that I should add
>extra cable TV and phone outlets. I assume that each time the
>cable is split up to go to each outlet, the signal strength is
>lowered. I would like to add a new outlet to each wall (or at
>least every other wall) in 3 or four rooms. What's the best
>way to wire this and how do you prevent signal loss. I'm talking
>about 10 or more outlets in the whole house. Same goes for the
>phone outlets. Of course I won't be using all of them at the same
>time, but I want the options of hooking up 2 or 3 TVs and phones
>and being able to change their locations without running a new
>cable every time.
Your idea of installing all this wiring makes a lot of sense to me.
In keeping with the idea that you will only be using 2-3 outlets at
any given time, I would personally wire each outlet independently (or
may be no more than 2 outlets per cable), and to only connect the ones
that you are using to the main feed.
That way, you won't have the 'pull' associated with many outlets, yet
you will be able to change outlets at will simply by changing which
wire is actively connected to the main feed.
In a way, it's sort'a like a computer networking system. All outlets
are wired, but only a few are hooked up to the patch panel/server.
I hope this helps. (Feel free to email me on this)
JP
ra...@joesbar.cc.vt.edu
INVALID ADDRESS: Use only REPLY-TO address (CCP...@AUDUCADM.DUC.AUBURN.EDU) wrote:
: I'm remodeling my old house. I figured that since I have the
: drywall removed from the walls and ceiling, that I should add
: extra cable TV and phone outlets. I assume that each time the
: cable is split up to go to each outlet, the signal strength is
: lowered. I would like to add a new outlet to each wall (or at
: least every other wall) in 3 or four rooms. What's the best
: way to wire this and how do you prevent signal loss. I'm talking
: about 10 or more outlets in the whole house. Same goes for the
: phone outlets. Of course I won't be using all of them at the same
: time, but I want the options of hooking up 2 or 3 TVs and phones
: and being able to change their locations without running a new
: cable every time.
Your best bet is to "home run" all your cables to some central location.
Probably where the phone and cable come into the house. The cable ends
should all be labeled and then you just hook up the ones you need at
the time.
If I were doing this, I would probably run category 5 for the phone lines
with some extra pairs. This way, you have the basis for a home automation
network already in place. You might want to run an extra TV cable to
each site as well. Cable is cheap compared to the labor to install it,
and some cable systems have a two-cable set up to carry more channels.
Or, the extra cable might just come in handy for something else.
--
*****************************************************************************
* Bill Ranck +1-540-231-3951 ra...@vt.edu *
* Virginia Polytechnic Institute & State University, Computing Center *
*****************************************************************************
Ken Jongsma
Telephone and TV should always be "homerunned" back to the entrypoint
of the house. If you split behind a wall or ceiling, you're asking for
trouble and unacceptable signal loss.
CCP...@AUDUCADM.DUC.AUBURN.EDU
>I'm remodeling my old house. I figured that since I have the
>drywall removed from the walls and ceiling, that I should add
>extra cable TV and phone outlets. I assume that each time the
>cable is split up to go to each outlet, the signal strength is
>lowered. I would like to add a new outlet to each wall (or at
>least every other wall) in 3 or four rooms. What's the best
>way to wire this and how do you prevent signal loss. I'm talking
>about 10 or more outlets in the whole house. Same goes for the
>phone outlets. Of course I won't be using all of them at the same
>time, but I want the options of hooking up 2 or 3 TVs and phones
>and being able to change their locations without running a new
>cable every time.
>
Jim Sokoloff
CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
> I'm remodeling my old house. I figured that since I have the
> drywall removed from the walls and ceiling, that I should add
> extra cable TV and phone outlets. I assume that each time the
> cable is split up to go to each outlet, the signal strength is
> lowered. I would like to add a new outlet to each wall (or at
> least every other wall) in 3 or four rooms. What's the best
> way to wire this and how do you prevent signal loss. I'm talking
> about 10 or more outlets in the whole house. Same goes for the
> phone outlets. Of course I won't be using all of them at the same
> time, but I want the options of hooking up 2 or 3 TVs and phones
> and being able to change their locations without running a new
> cable every time.
Whether you indeed to use them all at once or not, wire all the cables
to a single point in the house. (One cable per outlet, each cable ends
in a patch panel somewhere in the basement, closet, whatever.) This
permits you to re-configure the cabling at the patch panel, and you
don't have to drive all outlets. (Each open outlet has the potential
to introduce noise in addition to just lowering the signal strength.)
Strongly consider installing double runs to any location that is
likely to be a "main" entertainment center (ie likely to have a VCR.)
This way, you can use that VCR as a source to drive TVs in the rest of
the house.
For more information, consider comp.home.automation.
---Jim
Michael Nolan
CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
>I'm remodeling my old house. I figured that since I have the
>drywall removed from the walls and ceiling, that I should add
>extra cable TV and phone outlets. I assume that each time the
>cable is split up to go to each outlet, the signal strength is
>lowered.
According to my electrican, every splitter will reduce the signal strength
by about 3dB. (If I remember my math from the early 1970's, that's about
10%.) 3 and 4 way splitters might not reduce the strength by as much per
output.
In my experience, splitting your cable input to more than about 5 lines
will cause a noticeable degradation in picture quality. Your cable company can
advise you as to the limits of their signal, and also as to whether they
place any limits on signal splitting. (Most don't these day, except to
advise you that you will need an amplifier if you have too many outlets.)
I've seen some recommendations that you have the cable company bring in
two independent feeds into the house so that you have more signal strength
to start with, I don't know if this is something most cable companies will
do, though.
I would like to add a new outlet to each wall (or at
>least every other wall) in 3 or four rooms. What's the best
>way to wire this and how do you prevent signal loss. I'm talking
>about 10 or more outlets in the whole house.
The best solution is to put in a video distributor, which will amplify
the signal split off to each port. USTEC makes several models, with anywhere
from 10 to 20 ports per unit, and they can be ganged together. This can
also be used to feed video signals back to be accessed at other locations,
though if you're on cable to do this right you'll probably need to
modulate the signal to an unallocated channel (probably above 100), and
bypass your cable converter to view it. (Split the signal at the TV and
feed the raw signal to input A, and the converter output to input B.)
>Same goes for the
>phone outlets. Of course I won't be using all of them at the same
>time, but I want the options of hooking up 2 or 3 TVs and phones
>and being able to change their locations without running a new
>cable every time.
If you want to use more than 4 or 5 phones, you may want to consider
a local PBX system. We have a Panasonic unit that is capable of supporting
16 extensions and 6 outside lines. It also gives us room to room intercom
capability, and we don't need to worry about 'ring equivalence' numbers
as a result. We actually pulled 32 phone extensions, and have them wired
back to a patch panel in the basement, so I can switch which extensions
are live (and renumber them) quickly. (It sounds like a lot of
extensions, but there are 6 jacks in the master suite alone, one on each
wall and two more in my wife's sitting room.) We used cat-5 cable,
which you will need for a PBX, since most use 6 or 8 conductors.
BTW, a better place to ask questions like this is in comp.home.automation.
--
Mike Nolan
ra...@joesbar.cc.vt.edu
Michael Nolan (no...@inetnebr.com) wrote:
: CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
: >I'm remodeling my old house. I figured that since I have the
: >drywall removed from the walls and ceiling, that I should add
: >extra cable TV and phone outlets. I assume that each time the
: >cable is split up to go to each outlet, the signal strength is
: >lowered.
: According to my electrican, every splitter will reduce the signal strength
: by about 3dB. (If I remember my math from the early 1970's, that's about
: 10%.) 3 and 4 way splitters might not reduce the strength by as much per
: output.
Well, your math may need some help. A 2-way split gives you about
1/2 the signal level in each output (with a smidge of extra loss)a
Figure 50% for each 2-way split. A 4-way split just doubles the loss,
in other words 25% signal level.
: In my experience, splitting your cable input to more than about 5 lines
: will cause a noticeable degradation in picture quality. Your cable company can
: advise you as to the limits of their signal, and also as to whether they
: place any limits on signal splitting. (Most don't these day, except to
: advise you that you will need an amplifier if you have too many outlets.)
This is pretty much a case-by-case situation. It depends on factors
such as how close to the cable company's line amp you are located,
and how well engineered their system is. Running all the cables to
a central point also helps this, because you can run a distribution
amplifier if you need to. But, the cable company will probably be
able to supply enough signal level for anyhting less than about
10 TV's I would guess.
: I've seen some recommendations that you have the cable company bring in
: two independent feeds into the house so that you have more signal strength
: to start with, I don't know if this is something most cable companies will
: do, though.
This doesn't make much sense to me. Why risk multi-path problems with
multiple feeds when a distribution amp would solve the problem?
Harry Mishugun
On 30 Jan 1998 21:28:59 GMT, ra...@joesbar.cc.vt.edu () wrote:
>Michael Nolan (no...@inetnebr.com) wrote:
>: CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
>
>: >I'm remodeling my old house. I figured that since I have the
>: >drywall removed from the walls and ceiling, that I should add
>: >extra cable TV and phone outlets. I assume that each time the
>: >cable is split up to go to each outlet, the signal strength is
>: >lowered.
>
>: According to my electrican, every splitter will reduce the signal strength
>: by about 3dB. (If I remember my math from the early 1970's, that's about
>: 10%.) 3 and 4 way splitters might not reduce the strength by as much per
>: output.
>
>Well, your math may need some help. A 2-way split gives you about
>1/2 the signal level in each output (with a smidge of extra loss)a
>Figure 50% for each 2-way split. A 4-way split just doubles the loss,
>in other words 25% signal level.
Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
50%. The original poster was correct with an approximate 3dB loss.
>
>: In my experience, splitting your cable input to more than about 5 lines
>: will cause a noticeable degradation in picture quality. Your cable company can
>: advise you as to the limits of their signal, and also as to whether they
>: place any limits on signal splitting. (Most don't these day, except to
>: advise you that you will need an amplifier if you have too many outlets.)
>
>Running all the cables to a central point also helps this, because you
>can run a distribution amplifier if you need to.
Just like you can with a single run. You'll have no quality loss.
>But, the cable company will probably be able to supply enough signal
>level for anyhting less than about 10 TV's I would guess.
>
By your own example earlier, the last 8 TVs would be unwatchable because you
would be splitting the signal. Are you changing your mind now?
You could add 500 TV's to your home off the single feed. You just need a signal
booster for (up to) every 5 sets you use off the source feed. You can boost a
previously boosted signal later down the line with no problem. As long as your
wiring is clean and shielded properly, it works fine.
Harry Mishugun
On Fri, 30 Jan 1998 20:02:05 GMT, kjon...@compuserve.com (Ken Jongsma) wrote:
>Telephone and TV should always be "homerunned" back to the entrypoint
>of the house. If you split behind a wall or ceiling, you're asking for
>trouble and unacceptable signal loss.
With telephone??!! I don't think so. You can jump from jack to jack all
through the house and you'll have absolutely zero quality loss.
As far as cable goes, that what signal boosters are for. It's cheaper than
running 100's of feet of unnecessary cable. The result will be a sharper
picture because you are boosting the signal.
>
>
>CCP...@AUDUCADM.DUC.AUBURN.EDU
>
>>I'm remodeling my old house. I figured that since I have the
>>drywall removed from the walls and ceiling, that I should add
>>extra cable TV and phone outlets. I assume that each time the
>>cable is split up to go to each outlet, the signal strength is
>>lowered. I would like to add a new outlet to each wall (or at
>>least every other wall) in 3 or four rooms. What's the best
>>way to wire this and how do you prevent signal loss. I'm talking
>>about 10 or more outlets in the whole house. Same goes for the
>>phone outlets. Of course I won't be using all of them at the same
>>time, but I want the options of hooking up 2 or 3 TVs and phones
>>and being able to change their locations without running a new
>>cable every time.
>>
Harry Mishugun
On 30 Jan 1998 15:19:20 -0500, "Jim Sokoloff" <soko...@tiac.net> wrote:
>CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
>
>> I'm remodeling my old house. I figured that since I have the
>> drywall removed from the walls and ceiling, that I should add
>> extra cable TV and phone outlets. I assume that each time the
>> cable is split up to go to each outlet, the signal strength is
>> lowered. I would like to add a new outlet to each wall (or at
>> least every other wall) in 3 or four rooms. What's the best
>> way to wire this and how do you prevent signal loss. I'm talking
>> about 10 or more outlets in the whole house. Same goes for the
>> phone outlets. Of course I won't be using all of them at the same
>> time, but I want the options of hooking up 2 or 3 TVs and phones
>> and being able to change their locations without running a new
>> cable every time.
>
>Whether you indeed to use them all at once or not, wire all the cables
>to a single point in the house. (One cable per outlet, each cable ends
>in a patch panel somewhere in the basement, closet, whatever.)
People, people. This is unnecessary and is more costly/more labor intensive.
But do it if you want. Seems to be a rather popular and wasteful thing to do.
Harry Mishugun
On 30 Jan 1998 14:59:16 -0600, no...@inetnebr.com (Michael Nolan) wrote:
>CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
>
>>I'm remodeling my old house. I figured that since I have the
>>drywall removed from the walls and ceiling, that I should add
>>extra cable TV and phone outlets. I assume that each time the
>>cable is split up to go to each outlet, the signal strength is
>>lowered.
>
>According to my electrican, every splitter will reduce the signal strength
>by about 3dB. (If I remember my math from the early 1970's, that's about
>10%.) 3 and 4 way splitters might not reduce the strength by as much per
>output.
>
>In my experience, splitting your cable input to more than about 5 lines
>will cause a noticeable degradation in picture quality.
I've found it to be more like 4, but I'm sure that depends on each cable co.
A signal booster from Radio Shack will cure the problem very nicely.
Harry Mishugun
On 30 Jan 1998 19:47:01 GMT, ra...@joesbar.cc.vt.edu () wrote:
>INVALID ADDRESS: Use only REPLY-TO address (CCP...@AUDUCADM.DUC.AUBURN.EDU) wrote:
>: I'm remodeling my old house. I figured that since I have the
>: drywall removed from the walls and ceiling, that I should add
>: extra cable TV and phone outlets. I assume that each time the
>: cable is split up to go to each outlet, the signal strength is
>: lowered. I would like to add a new outlet to each wall (or at
>: least every other wall) in 3 or four rooms. What's the best
>: way to wire this and how do you prevent signal loss. I'm talking
>: about 10 or more outlets in the whole house. Same goes for the
>: phone outlets. Of course I won't be using all of them at the same
>: time, but I want the options of hooking up 2 or 3 TVs and phones
>: and being able to change their locations without running a new
>: cable every time.
>
>Your best bet is to "home run" all your cables to some central location.
Why? This just wastes cable. Each run can have 3-4 splits in it with no
degradation in picture quality. Using a cable power booster at the start of the
feed will make a big difference. You can get them with 1 input and up to 5
outputs. Cost less than $20.
If you have a wall that you want to put 3 cable jack on, just run one cable and
put a splitter at each jack.
If you run phone cable, just split from jack to jack. There is absolutely no
need to run single wires back to the box for phone.
>If I were doing this, I would probably run category 5 for the phone lines
>with some extra pairs.
You can pick up 6 or 8 conductor phone cable at most home supply stores. This
will allow for up to 3 or 4 seperate phone numbers at each jack.
Michael Nolan
unid...@mindspring.com writes:
>On Fri, 30 Jan 1998 23:05:17 GMT, hm...@yulet.net (Harry Mishugun) wrote:
>>With telephone??!! I don't think so. You can jump from jack to jack all
>>through the house and you'll have absolutely zero quality loss.
>Where are you getting this misinformation from? Running the phone line in
>a loop will almost insure that you are going to find a hell of a lot of
>cross talk between the lines!
IMHO the big advantage of running phone lines to a central location is that
it makes it possible to put in a PBX now or later, in which case each line
can be a separate extension. If Cat-5 cabling is used (and properly
terminated), you can even put your own Ethernet in your house. (We have
both an Ethernet and a Panasonic PBX in our house.)
Yeah it cost more than daisy chaining from one location to another, but
crosstalk is virtually eliminated.
Our PBX is nice to have, with station-to-station intercom capability, outside
line hunting, call transfer, etc. (At first my wife objected to having to
dial '9' to make an outside call, like in a hotel, but she got used to it.)
>>As far as cable goes, that what signal boosters are for. It's cheaper than
>>running 100's of feet of unnecessary cable. The result will be a sharper
>>picture because you are boosting the signal.
>This is totally false - the picture will suffer degradation and the signal
>will be practically wiped out by the electronic noise the boosters and
>spliters will introduce!
A good video distribution system, like USTEC, introduces virtually no noise
as it amplifies.
--
Mike Nolan
Michel Gagnon
INVALID ADDRESS: Use only REPLY-TO address
> I'm remodeling my old house. I figured that since I have the
> drywall removed from the walls and ceiling, that I should add
> extra cable TV and phone outlets. I assume that each time the
> cable is split up to go to each outlet, the signal strength is
> lowered. I would like to add a new outlet to each wall (or at
> least every other wall) in 3 or four rooms. What's the best
> way to wire this and how do you prevent signal loss. I'm talking
> about 10 or more outlets in the whole house. Same goes for the
> phone outlets. Of course I won't be using all of them at the same
> time, but I want the options of hooking up 2 or 3 TVs and phones
> and being able to change their locations without running a new
> cable every time.
>
> Please post or email me by removing *NOSPAM* from my address.
> --
> Reply only to edwarwd@*NOSPAM*mail.auburn.edu
> NOTICE: Mail sent to the FROM address will be bounced.
Cable SHOULD be run in a home-run configuration. You should run a cable
from each of the proposed outlets to a central location (in the
basement, for example). For a neat installation, you should install
proper screw-in adaptors to each of the lines, and simply connect to
splitters the lines you are using. Then, when you move the TV to a
different wall (or room), this will mean that you will disconnect one
line (in the basement) and connect another one in place.
Similarly, phone could be run in a daisy chain (from one outlet to the
next), but is better run in a "home-run" configuration, as it is much
easier to find broken connections and to upgrade the system.
If you have a single phone line, you could simply tie all wires together
using wire nuts (red with reds, green with greens, etc.); if you get a
new phone line for the computer or the home office, it would be a simple
task to isolate these wires and affect them to the new line, for
example. And if you want a more professional job, you should tie these
phone wires in a "patch panel", which would enable you to even install
an office-like telephone system if you want.
Check these two pages for more info. They are "amateur" pages whose
reference I had for a long time, so I hope they still work.
<http://www.mcdata.com/~meh0045/homewire/wire_guide.html>
<http://www.geocities.com/ResearchTriangle/3300/>
--
Michel Gagnon -- Montréal (Québec, Canada)
Michel...@videotron.ca
Michel Gagnon
Harry Mishugun <hm...@yulet.net> wrote:
> On 30 Jan 1998 21:28:59 GMT, ra...@joesbar.cc.vt.edu () wrote:
>
> >Michael Nolan (no...@inetnebr.com) wrote:
> >: CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS) writes:
.....
> >
> >Running all the cables to a central point also helps this,
> >because youcan run a distribution amplifier if you need to.
>
> Just like you can with a single run. You'll have no quality loss.
>
.....
>
> You could add 500 TV's to your home off the single feed.
> You just need a signal
> booster for (up to) every 5 sets you use off the source feed.
> You can boost a
> previously boosted signal later down the line with no problem.
> As long as your
> wiring is clean and shielded properly, it works fine.
There are differences between homeruns and daisy chain. With homeruns,
you will be installing, say, 30 cables for 30 outlets, but you will only
connect 3 or 4 of them. Therefore, you will have only one four-way
splitter, and each TV will get 1/4 of the signal. With daisy chain, on
the other hand, you will have one splitter installed at each cable
outlet. The first outlet near the cable entrance will get 50 % of the
feed (whether there is a TV or not), the second one will get 50 % x 50 %
(or 25 %), etc, so, if your main TV happens to be at the end of the
daisy chain, you will get a very week signal indeed.
Jim Sokoloff
hm...@yulet.net (Harry Mishugun) writes:
> Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
> 50%. The original poster was correct with an approximate 3dB loss.
What the hell math are you doing? A 3db loss IS a 50%
drop... (Actually, it's a 49.88% drop, but who's counting that
closely?)
db is an expression of the ratio of power between two sources,
defined as:
db = 10 log10 (P1 / P2)
Solving this (using math that is decidely not irrelevant) for -3db (a
3db loss), we get P1/P2 = 10**(-0.3) or (drumroll, please): 0.501187
---Jim
Jim Sokoloff
hm...@yulet.net (Harry Mishugun) writes:
> As far as cable goes, that what signal boosters are for. It's cheaper than
> running 100's of feet of unnecessary cable. The result will be a sharper
> picture because you are boosting the signal.
Right, because as well all know, the more amplifiers in a signal
chain, the cleaner and less distorted the signal...
EVERY amplifier, even fancy-pants full class-A amplifiers introduce
noise into the signal. If you can cable such that amplifiers are not
needed, you WILL get a better signal to the TV...
---Jim
Michael Nolan
"Jim Sokoloff" <soko...@tiac.net: writes:
:hm...@yulet.net (Harry Mishugun) writes:
I will admit that it has been over 25 years since I studied electrical
engineering, (and my less than brilliant grades in it were a major factor
in my decision to transfer to computer science) but according to Encyclopaedia
Britannica, when comparing the ratio of two electrical current, the decibel
formula is different than the formula used for comparing audio signals.
According to my encyclopaedia, one decibel is equal to 20 times the common
logarithm of the ratio of the voltages or currents being compared.
Accordingly, I would suggest that a 3dB loss in a splitter is equivalent to
about a 29 per cent signal loss, somewhat more than the 10% I suggested
earlier today, but somewhat less than 50%.
But my math may still be flawed here, and I would defer to a more
current student.
--
Mike Nolan
Shouradf
ED>I'm remodeling my old house. I figured that since I have the
ED>drywall removed from the walls and ceiling, that I should add
ED>extra cable TV and phone outlets.
You might also want to consider installing fiber-optic cables at the
sametime
so you'll be ready for future technologies. And instead of ordinary
phone wire,
you might want to consider using category 5 (UTP - twisted pair) that
would
bring the equivalent of 4 telephone lines to each drop. And the higher
quality
wire means cleaner connections, and for computer use higher transfer
speeds.
In my 3 br, 2.5 bath 1400 s.f. townhouse, each room is equipped with at
least
one "data outlet" with two Cat-5 jacks and 2 RG-6 coax jacks. All of
which is
"home run" to a central point. Thus allowing access to my home Local
Area
Network (LAN), up to 4 phone lines, and uplink / downlink of
audio/video. Any
VCR / Laser Disc player / DVD can be seen & controlled from any TV in
the
house. Check out comp.home.automation for more ideas on this as well
as
other home automation ideas you might want to take advantage of.
Radi
--
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Steve Goldman
I wonder if the discrepancy is because decibels are intended to measure
power, which is a function of either voltage or current squared.
P=I^2*R or P=V^2/R
So at a given impedance, a 29% reduction in current is a 50% reduction in
power.
Of course, as a chemical engineer, I really have no right to an opinion.
Regards,
Steve Goldman
Michael Nolan
Steve Goldman <ste...@ix.netcom.com> writes:
>I wonder if the discrepancy is because decibels are intended to measure
>power, which is a function of either voltage or current squared.
I think the reason for the difference is that SOUND radiates out in
3 dimensions, so it is diffused more, whereas ELECTRICITY stays in the
wires (well, mostly so).
However, the math itself isn't all that significant. What is important
is that splitters will decrease signal strength, and there is a point at
which the signal quality will become unacceptable. It would appear that
number is somewhere between 4 and 8 parts, and may be dependent on other
things like the strength of the cable signal and cable lengths, or on
the TV being used or one's visual tolerance for a noisy signal.
Splitting a signal to an UNUSED wire might cause less of a degradation,
though placing a terminator at the end to reduce ghosting would likely be
equivalent to placing a TV at the end.
Amplifiers can be used to boost signal strength, but will probably introduce
some noise in the process, whether that is an unacceptable situation or not
will depend on the number and quality of the amplifiers.
If it was me, and I was planning on hooking up more than a few TV's at
any one time, I'd home run the cables and use a video distribution system.
If I had only a few TV's and was willing to plug and unplug cables whenever
I moved or added a TV or other device, I'd probably just use splitters.
In our new house, we chose the former solution and used two USTEC TecGate
systems, each of which can handle 16 pair of video inputs and outputs.
We pulled 24 runs of dual RG6 cable to various spots around the house.
Each of these locations also has two Cat-5 RJ45 jacks on the same wallplate,
which are wired to two patch panels in the basement. (One for phone, one
for ethernet, though this is more a convenience for making changes than
a requirement to isolate phone from net cabling.) We pulled another 8 Cat-5
runs for additional phone locations.
Including the A/C, security, and home automation system wiring, my
electrician estimated he pulled over 8 miles of wires for this house.
--
Mike Nolan
Roger
>Michael Nolan wrote:
>>
>> "Jim Sokoloff" <soko...@tiac.net: writes:
>>
>> :hm...@yulet.net (Harry Mishugun) writes:
>>
>> :> Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
>> :> 50%. The original poster was correct with an approximate 3dB loss.
>>
The term "dB" always should refer to a power ratio, regardless of the
units used, thus -3dB refers to a power ratio of approx. 2:1, -6dB is
approx 4:1, etc. However, since we are often interested in the effect
of voltage ratios (applied to a constant load impedance), and since
power is proportionate to the square of the applied voltage, then -3dB
references a voltage ratio of .707, -6dB to a 2:1 votage ratio, etc.
In actuality, a typical TV 2-way splitter will show losses
considerably higher than a simple power division would indicate
because of additional losses due to mismatch. Typical losses range
from 4.5 to 8 dB for a 2-way splitter, depending on whether it's an
impedance type, or a simple resistive type.
An important point to remember in using a splitter (whether impedance
or resistive) is to terminate the unused output ports in the
characteristic impedance of the line (75 ohms). These loads are
sometimes included with the splitters, or may be purchased from Radio
Shack or elsewhere. An unused, unterminated port (especially at the
end of a cable) may cause reflections that result in picture
"ghosting" or loss of signal amplitude.
-- Roger r...@ricochet.net
Jim Sokoloff
no...@inetnebr.com (Michael Nolan) writes:
> Accordingly, I would suggest that a 3dB loss in a splitter is equivalent to
> about a 29 per cent signal loss, somewhat more than the 10% I suggested
> earlier today, but somewhat less than 50%.
Let's look at this another way:
1. The splitters are passive devices; as such, they cannot add power
to the system. (If you don't think they are passive devices, please
let us know where the power they add comes from.)
2. Presume that the cable company provides you with a fixed amount of
signal "power" to your house. This is probably very close to an
accurate assumption.
3. So, the splitters can only divide the power they have
available. This implies that a perfect 1-to-2 splitter will provide
exactly 50% of the input power to each output.
---Jim
Chris Matthaei
no...@inetnebr.com (Michael Nolan) writes:
>"Jim Sokoloff" <soko...@tiac.net: writes:
>:hm...@yulet.net (Harry Mishugun) writes:
>:> Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
>:> 50%. The original poster was correct with an approximate 3dB loss.
>:What the hell math are you doing? A 3db loss IS a 50%
>:drop... (Actually, it's a 49.88% drop, but who's counting that
>:closely?)
>:db is an expression of the ratio of power between two sources,
>:defined as:
>:db = 10 log10 (P1 / P2)
>:Solving this (using math that is decidely not irrelevant) for -3db (a
>:3db loss), we get P1/P2 = 10**(-0.3) or (drumroll, please): 0.501187
>I will admit that it has been over 25 years since I studied electrical
>engineering, (and my less than brilliant grades in it were a major factor
>in my decision to transfer to computer science) but according to Encyclopaedia
>Britannica, when comparing the ratio of two electrical current, the decibel
>formula is different than the formula used for comparing audio signals.
>According to my encyclopaedia, one decibel is equal to 20 times the common
>logarithm of the ratio of the voltages or currents being compared.
>Accordingly, I would suggest that a 3dB loss in a splitter is equivalent to
>about a 29 per cent signal loss, somewhat more than the 10% I suggested
>earlier today, but somewhat less than 50%.
>But my math may still be flawed here, and I would defer to a more
>current student.
I'm not a current student, but I have a problem with your answer based on
a more fundemental reason. If each output from the splitter only has a 29%
loss, that means each signal is 71% of the input signal. Sum these up and
you have 142% of the input power coming out of your splitter. Obviously
this is not true because it violates some law of themodynamics, or something.
(It has been a while :) ). There's no free lunch!
Chris
Harry Mishugun
On Fri, 30 Jan 1998 20:51:03 -0500, Michel...@videotron.ca (Michel Gagnon)
wrote:
>INVALID ADDRESS: Use only REPLY-TO address
><CCP...@AUDUCADM.DUC.AUBURN.EDU> wrote:
>
>> I'm remodeling my old house. I figured that since I have the
>> drywall removed from the walls and ceiling, that I should add
>> extra cable TV and phone outlets. I assume that each time the
>> cable is split up to go to each outlet, the signal strength is
>> lowered. I would like to add a new outlet to each wall (or at
>> least every other wall) in 3 or four rooms. What's the best
>> way to wire this and how do you prevent signal loss. I'm talking
>> about 10 or more outlets in the whole house. Same goes for the
>> phone outlets. Of course I won't be using all of them at the same
>> time, but I want the options of hooking up 2 or 3 TVs and phones
>> and being able to change their locations without running a new
>> cable every time.
>>
>> Please post or email me by removing *NOSPAM* from my address.
>> --
>> Reply only to edwarwd@*NOSPAM*mail.auburn.edu
>> NOTICE: Mail sent to the FROM address will be bounced.
>
>Cable SHOULD be run in a home-run configuration.
If you like to waste time and money.
>You should run a cable from each of the proposed outlets to a central location (in the
>basement, for example).
Why? Please provide just 1 legitimate example. Picture quality is not a valid
point as it will not suffer with a signal booster.
>
>Similarly, phone could be run in a daisy chain (from one outlet to the
>next), but is better run in a "home-run" configuration, as it is much
>easier to find broken connections and to upgrade the system.
How do stationary wires just 'break'?
Harry Mishugun
On Sat, 31 Jan 1998 00:51:45 GMT, unid...@mindspring.com wrote:
>On Fri, 30 Jan 1998 23:05:17 GMT, hm...@yulet.net (Harry Mishugun) wrote:
>
>>With telephone??!! I don't think so. You can jump from jack to jack all
>>through the house and you'll have absolutely zero quality loss.
>>
>
>Where are you getting this misinformation from? Running the phone line in
>a loop will almost insure that you are going to find a hell of a lot of
>cross talk between the lines!
Not if you use actual telephone or twisted pair cable. Where are you getting
YOUR misinformation from?
If you use mickey mouse wire that was never intended for telephone use, you'll
get all kinds of noise.
>>As far as cable goes, that what signal boosters are for. It's cheaper than
>>running 100's of feet of unnecessary cable. The result will be a sharper
>>picture because you are boosting the signal.
>
>This is totally false - the picture will suffer degradation and the signal
>will be practically wiped out by the electronic noise the boosters and
>spliters will introduce!
Maybe you should come to my home and see for yourself. I'm running 7 TV's off a
single run of coax. 1 booster in the middle. The sets on the other side of the
booster look much better than the first one off the street run.
You don't have a clue, now do you?
Harry Mishugun
On 30 Jan 1998 19:45:38 -0600, no...@inetnebr.com (Michael Nolan) wrote:
>unid...@mindspring.com writes:
>
>>On Fri, 30 Jan 1998 23:05:17 GMT, hm...@yulet.net (Harry Mishugun) wrote:
>
>>>With telephone??!! I don't think so. You can jump from jack to jack all
>>>through the house and you'll have absolutely zero quality loss.
>
>>Where are you getting this misinformation from? Running the phone line in
>>a loop will almost insure that you are going to find a hell of a lot of
>>cross talk between the lines!
>
>IMHO the big advantage of running phone lines to a central location is that
>it makes it possible to put in a PBX now or later, in which case each line
>can be a separate extension. If Cat-5 cabling is used (and properly
>terminated), you can even put your own Ethernet in your house. (We have
>both an Ethernet and a Panasonic PBX in our house.)
IF you think you'll ever have a need for this, then yes. For 98% of all
homeowners, this is overkill.
>
>Yeah it cost more than daisy chaining from one location to another, but
>crosstalk is virtually eliminated.
It's eliminated if you use the proper wire to begin with.
BKL
On 2 Feb 1998 09:43:54 -0600, fu...@MCS.COM (Chris Matthaei) wrote:
>I'm not a current student, but I have a problem with your answer based on
>a more fundemental reason. If each output from the splitter only has a 29%
>loss, that means each signal is 71% of the input signal. Sum these up and
>you have 142% of the input power coming out of your splitter. Obviously
>this is not true because it violates some law of themodynamics, or something.
>(It has been a while :) ). There's no free lunch!
Perhaps the numbers are right, and the signal strength is the square
(or square root) of something that is conserved, like energy.
Harry Mishugun
On Fri, 30 Jan 1998 22:13:30 -0500, Michel...@videotron.ca (Michel Gagnon)
wrote:
>Harry Mishugun <hm...@yulet.net> wrote:
Your example is not valid. Homeruns need to split somewhere, right? They are
splitting at the basement (or cable entry point), rather than at each outlet.
So, 10 TV's with homeruns will only receive 10% of the signal by your example.
You'll still need a signal amplifier.
Why waste all that time and cable when you'll need a signal booster anyway?
Harry Mishugun
On 30 Jan 1998 22:24:00 -0500, "Jim Sokoloff" <soko...@tiac.net> wrote:
>hm...@yulet.net (Harry Mishugun) writes:
>> As far as cable goes, that what signal boosters are for. It's cheaper than
>> running 100's of feet of unnecessary cable. The result will be a sharper
>> picture because you are boosting the signal.
>
>Right, because as well all know, the more amplifiers in a signal
>chain, the cleaner and less distorted the signal...
>
>EVERY amplifier, even fancy-pants full class-A amplifiers introduce
>noise into the signal. If you can cable such that amplifiers are not
>needed, you WILL get a better signal to the TV...
Not one you will notice. Not even with my 60". You are talking semantics, now.
Harry Mishugun
"Jim Sokoloff" soko...@tiac.net: writes:
>
>hm...@yulet.net (Harry Mishugun) writes:
>
>: Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
>: 50%. The original poster was correct with an approximate 3dB loss.
>
>What the hell math are you doing? A 3db loss IS a 50%
>drop... (Actually, it's a 49.88% drop, but who's counting that
>closely?)
I'm sorry, but this is just completely incorrect.
ra...@joesbar.cc.vt.edu
Harry Mishugun (hm...@yulet.net) wrote:
: On 30 Jan 1998 21:28:59 GMT, ra...@joesbar.cc.vt.edu () wrote:
: >Well, your math may need some help. A 2-way split gives you about
: >1/2 the signal level in each output (with a smidge of extra loss)a
: >Figure 50% for each 2-way split. A 4-way split just doubles the loss,
: >in other words 25% signal level.
: Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
: 50%. The original poster was correct with an approximate 3dB loss.
I'm sorry, but my math is not irrelevant. My math is correct. A 3dB loss
is 50% loss.
: >Running all the cables to a central point also helps this, because you
: >can run a distribution amplifier if you need to.
: Just like you can with a single run. You'll have no quality loss.
Yes, but if you run a poin-to-point loop you invariably end up
with extra splits (and thus extra loss) for unused drops. If you
home run everthing to a central point you only hook up what is
needed and minimize the splits. Plus, you can feed all drops with
an equal signal level, which is almost impossible with a "loop."
A home run for cabling is much better for flexibility, and the
cost of cable is cheap compared to trying to change it later if
you have to open up a wall somewhere.
: >But, the cable company will probably be able to supply enough signal
: >level for anyhting less than about 10 TV's I would guess.
: >
: By your own example earlier, the last 8 TVs would be unwatchable because you
: would be splitting the signal. Are you changing your mind now?
I gave no such earlier example. Cable companies feed a house with enough
signal level to drive a couple of TV's and VCR's. They *can* give you more
signal level, but generally do not because it would over-drive a single TV
if that's all you have. If you work with and talk to the cable company,
they can probably provide enough level for more.
Daman Grane
On 2 Feb 1998 19:24:33 GMT, ra...@joesbar.cc.vt.edu () wrote:
>Harry Mishugun (hm...@yulet.net) wrote:
>: On 30 Jan 1998 21:28:59 GMT, ra...@joesbar.cc.vt.edu () wrote:
>
>: >Well, your math may need some help. A 2-way split gives you about
>: >1/2 the signal level in each output (with a smidge of extra loss)a
>: >Figure 50% for each 2-way split. A 4-way split just doubles the loss,
>: >in other words 25% signal level.
>
>: Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
>: 50%. The original poster was correct with an approximate 3dB loss.
>
>I'm sorry, but my math is not irrelevant. My math is correct. A 3dB loss
>is 50% loss.
In the specific instance we are talking about it is more like 30%. Nice try.
You cannot effectively apply dB loss to a split A/V signal. Just doesn't work
that way.
Jim Sokoloff
hm...@yulet.net (Harry Mishugun) writes:
The point is that you'll not likely get a "sharper picture because you
are boosting the signal." I have a distribution amp in my house and I
have a perfectly acceptable picture on all my sets, but I don't claim
that the amp results in a better picture than originally came into the
house...
---Jim
Jim Sokoloff
dgr...@concentrics.net (Daman Grane) writes:
> On 2 Feb 1998 19:24:33 GMT, ra...@joesbar.cc.vt.edu () wrote:
>
> >Harry Mishugun (hm...@yulet.net) wrote:
> >: Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
> >: 50%. The original poster was correct with an approximate 3dB loss.
> >
> >I'm sorry, but my math is not irrelevant. My math is correct. A 3dB loss
> >is 50% loss.
> In the specific instance we are talking about it is more like 30%.
No, in the specific example, it's a 50% loss. The splitter doesn't
plug into any power source, and thus cannot amplify the
signal. (TANSTAAFL)
> Nice try. You cannot effectively apply dB loss to a split A/V
> signal. Just doesn't work that way.
Huh? A decibel is an expression of the ratio of power between two
signals. So, you certainly CAN apply it to the ratio of the power of
two RF signals. Perhaps *you* can't effectively apply the concept of
db loss to an RF signal but *one* can...
---Jim
Jim Sokoloff
hm...@yulet.net (Harry Mishugun) writes:
>
> "Jim Sokoloff" soko...@tiac.net: writes:
> >
> >hm...@yulet.net (Harry Mishugun) writes:
> >
> >: Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
> >: 50%. The original poster was correct with an approximate 3dB loss.
> >
> >What the hell math are you doing? A 3db loss IS a 50%
> >drop... (Actually, it's a 49.88% drop, but who's counting that
> >closely?)
>
> I'm sorry, but this is just completely incorrect.
Enlighten us then. Just saying it's wrong doesn't enlighten anyone
anymore than if I said the moon were made of green cheese.
---Jim
Jim Sokoloff
hm...@yulet.net (Harry Mishugun) writes:
> On Fri, 30 Jan 1998 20:51:03 -0500, Michel...@videotron.ca (Michel Gagnon)
> wrote:
> >Cable SHOULD be run in a home-run configuration.
>
> If you like to waste time and money.
Or, if you want an installation with maximum flexibility without
re-cabling. Just because *you* don't have a use for something means
that no one has a use for it.
I've got a 200 year old house that I'm rewiring for my and my family's
needs. You can bet that I'm only interested in opening up each wall
one time and doing the job correctly the first time. I won't be
penny-wise and pound-foolish and I don't recommend the same to anyone
I advise on UseNet. This post started with someone asking how to cable
their new home I believe. In that case, while the walls are open, I
think it's hard to recommend a less flexible option just because it
saves maybe three hours and 200 ft of $0.19/ft cable. Same reason I
don't recommend RG-59. Sure, lots of people have watched TV over worse
cable than RG-59 and been happy. But, RG-6QS is here, and using
anything less in a cable installation that I own seems silly.
> >You should run a cable from each of the proposed outlets to a
> >central location (in the basement, for example)
> Why? Please provide just 1 legitimate example. Picture quality is
> not a valid point as it will not suffer with a signal booster.
Video distribution. Suppose I want to pipe a single source to a couple
of my TVs. (In order to have a VCR in the entertainment room be able
to feed the TV in the master bedroom so I can finish watching a movie
in bed.)
Or, suppose I want to install a DSS and cable setup and only pipe DSS
to some outlets and cable to others. (Further suppose I'm not Kreskin
and can't know today which TV locations will be which.)
Or, suppose I want to be able to pipe locally-sourced video to only a
few TVs (such as piping CCTV security cameras to only the master
bedroom).
Or, suppose I want to only permit ABC, CBS, NBC, WB, UPN, Fox, and
Disney to go to the outlets in my kids room.
Or, suppose I want to install outlets on all four walls of every room
and decide later where I want to install TVs. Rather than buying
umpteen RF amps and driving a bunch of resistors for most outlets, I
only have to drive the outlets that have a TV, VCR, or DSS on it.
Or, I want to be able to constrain two or more TVs to watch the same
program. (Piping a movie, or stock market coverage, or the big game
from the entertainment room to the bathroom TVs and the kitchen TV so
that no one feels left out when they are preparing snacks or using the
comfort facilities.)
And of course I imagine that you'll argue that none of those are
legitimate examples because no one on UseNet can ever be wrong.
---Jim
Stan Debick
Jim makes some great points in favor of homerun cabling. Among the most
compelling is the relatively low increased cost. My recent construction of
new home utilized homerun wiring for both phone and cable lines. Cost
savings if I would have daisy chained the whole thing would have been <$90,
hardly a fortune when considering new construction or remodeling.
There are other benefits as well. Harry questioned how a cable breaks or
goes bad when hidden in a wall. I am not about to propose a mechanism, but
I can attest that it happens. In my old house, all of the phone lines were
daisy chained together. There was no significant loss of sound quality (3
phones), but the cable that went from the network interface box to the first
phone in the chain failed. Result: no working phones in the house. If
this had been homerun wiring, no problem. The other phones work, and you
can repair the bad line when time permits.
Just my $0.02, or am I just wasting money again? :-)
Jim Sokoloff wrote in message ...
Michael Nolan
I have a potential 'solution' to the math argument in the cable TV splitter
question.
Could it be that it is the splitter itself that introduces a 3 dB signal
loss? As I recall, there are some resistive or capacitance components inside
a splitter that are there to reduce echo and ghosting problems, surely
these must sap up some of the signal.
We were doing some testing of a security camera a while back, and needed
to connect two cables together to test a camera at an alternate location.
I didn't have double 'F' connector handy, so we used a 3 way splitter.
There was very noticeable signal degradation compared to plugging the camera
into the original piece of cable.
As to the question of whether splitting the signal decreases the power,
electricity isn't like a water pipe. Unless there's a LOAD at the end of
a cable, why should it consume any power at all, except for the wire itself?
Put a TV at the other end, or a terminating cap, and then there is something
consuming power.
If this explains the situation, then splitting a signal into two parts
means that the load at each end gets somewhat less than half the original
signal strength.
--
Mike Nolan
Michel Gagnon
Harry Mishugun <hm...@yulet.net> wrote:
>.......
> >
> >Cable SHOULD be run in a home-run configuration.
>
> If you like to waste time and money.
>
> >You should run a cable from each of the proposed outlets to a central
> > location (in the basement, for example).
>
> Why? Please provide just 1 legitimate example.
> Picture quality is not a valid
> point as it will not suffer with a signal booster.
Please see my other post.
>
> >
> >Similarly, phone could be run in a daisy chain (from one outlet to the
> >next), but is better run in a "home-run" configuration, as it is much
> >easier to find broken connections and to upgrade the system.
>
> How do stationary wires just 'break'?
True, but it may happen either because mouldings were installed through
them, someone pulled a wire where it was accessible, someone played too
much with connectors, because water infiltrations made the cable rust. I
know in theory it should never happen, but in all the appartments I
occupied, there always were one or two bad connections. In one case, I
even had a piece of badly rusted telephone cable IN THE WALL. When such
a problem happens in a daisy chain, the problem affects all outlets
downwards, rather than just a single one.
Is it an overkill? It depends. If you know what your needs will be 10 or
20 years from now and if you install only (cable and telephone) outlets
where you need them -- like most people do, you will have only 5 or 6
outlets and yes, it may be an overkill. If, on the other hand, you want
to install telephone and cable outlets every 4 m (13 ft) -- like the
original poster suggested and like electrical receptacles are normally
installed --, you will have 6 or 7 telephone and cable outlets PER ROOM,
or 40 to 50 per house, and you need some kind of distribution panel.
Otherwise, when there is "static on the line" or a dead phone at the
furthest point in the house, it becomes very hard to find where is the
problem: 30 connection boxes to check times 6 wire connections per box
makes a lot of headaches!
Why am I installing that many outlets per room? I tend to renovate one
room every 2 or 3 years, and, when I am done, I don't want to paint them
for at least 10 years. And barring any disaster, I don't want to
renovate it again until I retire. This means that the room we just did
for our toddler should be able to fit when she grows up. Will she have a
phone in her room? Or a computer? Maybe a T.V.? Where will the bed and
computer be located? God knows! The room, however, will be ready.
Do you need to go that way? NO! Just like no one but North Americans
(and Europeans) NEED a 100 sq metres (1000 sq ft) for 4 people! That's a
choice we can make and likewise, that type of cabling is a choice we can
make... or not.
By the way, look a bit at <news:comp.home.automation> and you will find
that a lot of people have even more elaborate settings than that!
Michel Gagnon
Harry Mishugun <hm...@yulet.net> wrote:
> On Fri, 30 Jan 1998 22:13:30 -0500, Michel...@videotron.ca (Michel Gagnon)
> wrote:
>
.....
> >
> >There are differences between homeruns and daisy chain. With homeruns,
> >you will be installing, say, 30 cables for 30 outlets, but you will only
> >connect 3 or 4 of them. Therefore, you will have only one four-way
> >splitter, and each TV will get 1/4 of the signal. With daisy chain, on
> >the other hand, you will have one splitter installed at each cable
> >outlet. The first outlet near the cable entrance will get 50 % of the
> >feed (whether there is a TV or not), the second one will get 50 % x 50 %
> >(or 25 %), etc, so, if your main TV happens to be at the end of the
> >daisy chain, you will get a very week signal indeed.
>
> Your example is not valid. Homeruns need to split somewhere, right? They are
> splitting at the basement (or cable entry point), rather than at each outlet.
>
> So, 10 TV's with homeruns will only receive 10% of the signal by your example.
> You'll still need a signal amplifier.
>
> Why waste all that time and cable when you'll need a signal booster anyway?
Ten TVs will need 10 splitters. But, as I said, if your daisy chaining
makes you install 30 or 40 splitters because you install many spare
outlets along the road, when in fact you will only have two TVs, then
you will notice the difference. On the other hand, there are other more
creative ways to avoid using unnecessary splitters, like leaving a loop
of wire behind the wall and installing the outlet only when needed, but
I find them less convenient.
Jim Sokoloff
Michel...@videotron.ca (Michel Gagnon) writes:
> Harry Mishugun <hm...@yulet.net> wrote:
> > How do stationary wires just 'break'?
>
> True, but it may happen either because mouldings were installed through
> them, someone pulled a wire where it was accessible, someone played too
> much with connectors, because water infiltrations made the cable rust. I
> know in theory it should never happen, but in all the appartments I
> occupied, there always were one or two bad connections. In one case, I
> even had a piece of badly rusted telephone cable IN THE WALL. When such
> a problem happens in a daisy chain, the problem affects all outlets
> downwards, rather than just a single one.
Add: Wires are pinched or over-stressed when the house settles,
someone drives an errant nail or cuts them with an errant saw blade,
rodents chew on them, a short causes an electrical fire just big
enough to fry the cable. It's true that none of these things are
individually very likely, and reliability is not a sufficient argument
by itself to home run phone cable. (Flexibility is a sufficient
argument, IMO.)
> Do you need to go that way? NO! Just like no one but North Americans
> (and Europeans) NEED a 100 sq metres (1000 sq ft) for 4 people! That's a
> choice we can make and likewise, that type of cabling is a choice we can
> make... or not.
Hey, how can you fit *that many* people in only 100 square meters. :-)
---Jim
INVALID ADDRESS: Use only REPLY-TO address
There have been a lot of good answers to my post, but none of
them have given me a good clear answer on which is better or
how to install them. Here is what I'm thinking about doing:
Put an access panel in some out of the way place in each room.
It could be as small as the (or actually be) an outlet's cover
plate. Homerun all the wall cables for that room to that access
panel. From each room's access panel I will homerun one cable
to a whole house access pannel where the cable (or DBS) enters
the house.
The idea is to eliminate so many splits and only add them in
the access panels where needed. This gives the advantage of only
connecting the cables which are actually in use, but allows you
to switch them easily. For example: I have 5 rooms wired for
cable and a cable outlet in each of the room's 4 walls. That
would be 20 homerun cables or a lot a splitters using some of
the other's ideas. In my plan I would have only 5 cables run
form the house panel and only connect the cable going to the
room where it's needed. In each room I would have 4 cables
run to that room's panel and again only connect the cable to
the wall where it's needed.
* 1 TV = only connect 1 room's cable connected to 1 wall's cable
= no splitters. Just change connections when you changes locations.
* 1 TV in 2 rooms = a cable to each room connected to 1 wall's
cable in each room = 1 splitter at whole house access panel.
* If you add a TV and VCR in the same room, the VCR has it's
own TV outlet so you may not even need a splitter. If you
do you can always add 1 to the room's access panel or just
add 1 to the cable after it exits the wall especially if the
receivers are next to each other.
* Of course, if you have multi receivers in use in every room
then you are going to have a problem no matter how you wire it.
What do y'all think? Don't make me resort to calling the cable
company and asking their experts (HA)!!!!
edwarwd@mail*NOSPAM*.auburn.edu
ra...@joesbar.cc.vt.edu
INVALID ADDRESS: Use only REPLY-TO address (CCP...@AUDUCADM.DUC.AUBURN.EDU) wrote:
: There have been a lot of good answers to my post, but none of
: them have given me a good clear answer on which is better or
: how to install them. Here is what I'm thinking about doing:
:
: Put an access panel in some out of the way place in each room.
: It could be as small as the (or actually be) an outlet's cover
: plate. Homerun all the wall cables for that room to that access
: panel. From each room's access panel I will homerun one cable
: to a whole house access pannel where the cable (or DBS) enters
: the house.
Well, that sounds OK, but I would at least run 2 cables from
the room sub-panels to the house panel. This gives you the
possibility of feeding signal from a VCR/DVD/LD to other
TV's back through the second cable. Personally, I'd still
home run everything back to one central point. Cable is
cheap. On the other hand, your idea is a good compromise
which should work fine, but think about adding a second
cable to/from the sub-panels for expansion/backup.
: to switch them easily. For example: I have 5 rooms wired for
: cable and a cable outlet in each of the room's 4 walls. That
: would be 20 homerun cables or a lot a splitters using some of
: the other's ideas. In my plan I would have only 5 cables run
: form the house panel and only connect the cable going to the
: room where it's needed. In each room I would have 4 cables
: run to that room's panel and again only connect the cable to
: the wall where it's needed.
Actually, what you are describing is similar to how our
university wires cable-TV to the dorms. A main panel feeds
sub-panels on each floor. The sub-panels have connections
for each room that can be hooked up as needed.
Eric Gunnerson
INVALID ADDRESS: Use only REPLY-TO address wrote in message
<1998013011...@AUDUCADM.DUC.AUBURN.EDU>...
>I'm remodeling my old house. I figured that since I have the
>drywall removed from the walls and ceiling, that I should add
>extra cable TV and phone outlets. I assume that each time the
>cable is split up to go to each outlet, the signal strength is
>lowered. I would like to add a new outlet to each wall (or at
>least every other wall) in 3 or four rooms. What's the best
>way to wire this and how do you prevent signal loss. I'm talking
>about 10 or more outlets in the whole house. Same goes for the
>phone outlets. Of course I won't be using all of them at the same
>time, but I want the options of hooking up 2 or 3 TVs and phones
>and being able to change their locations without running a new
>cable every time.
Others have commented well on wiring.
My suggestion is that you run conduit so that you can pull other lines later
if you need them. You might, for example, want fiber in 5 or 10 years, and
it will be trivial to pull it from the central location if you do conduit.
Just make sure that you leave a piece of nylon twine in each run.
danh...@millcomm.com
In <1998020310...@AUDUCADM.DUC.AUBURN.EDU>, CCP...@AUDUCADM.DUC.AUBURN.EDU (INVALID ADDRESS: Use only REPLY-TO address) writes:
>There have been a lot of good answers to my post, but none of
>them have given me a good clear answer on which is better or
>how to install them. Here is what I'm thinking about doing:
>
>Put an access panel in some out of the way place in each room.
>It could be as small as the (or actually be) an outlet's cover
>plate. Homerun all the wall cables for that room to that access
>panel. From each room's access panel I will homerun one cable
>to a whole house access pannel where the cable (or DBS) enters
>the house.
What if you want to "originate" from a room -- broadcast back to other
sets, as with a VCR? I'd at least run two cables from each room that
might eventually host a "home entertainment center".
Dan Hicks
Hey!! My advice is free -- take it for what it's worth!
http://www.millcomm.com/~danhicks
David Winslow
Daman Grane wrote in message <34d621b8...@news.zippo.com>...
>On 2 Feb 1998 19:24:33 GMT, ra...@joesbar.cc.vt.edu () wrote:
>
>>Harry Mishugun (hm...@yulet.net) wrote:
>>: On 30 Jan 1998 21:28:59 GMT, ra...@joesbar.cc.vt.edu () wrote:
>>
>>: >Well, your math may need some help. A 2-way split gives you about
>>: >1/2 the signal level in each output (with a smidge of extra loss)a
>>: >Figure 50% for each 2-way split. A 4-way split just doubles the loss,
>>: >in other words 25% signal level.
>>
>>: Uh, your math is irrelevant here. 2-way splitters do not drop the
signal by
>>: 50%. The original poster was correct with an approximate 3dB loss.
>>
>>I'm sorry, but my math is not irrelevant. My math is correct. A 3dB loss
>>is 50% loss.
>
>In the specific instance we are talking about it is more like 30%. Nice
try.
IWhat school of electronics does this come from. The math above is
perfectly correct.
>
>You cannot effectively apply dB loss to a split A/V signal. Just doesn't
work
>that way.
Why don't you tell us how it does work.
David Winslow
Michael Nolan wrote in message <6b5t9i$dlk$1...@falcon.inetnebr.com>...
>I have a potential 'solution' to the math argument in the cable TV splitter
>question.
>
>Could it be that it is the splitter itself that introduces a 3 dB signal
>loss? As I recall, there are some resistive or capacitance components
inside
>a splitter that are there to reduce echo and ghosting problems, surely
>these must sap up some of the signal.
>
>We were doing some testing of a security camera a while back, and needed
>to connect two cables together to test a camera at an alternate location.
>
>I didn't have double 'F' connector handy, so we used a 3 way splitter.
>There was very noticeable signal degradation compared to plugging the
camera
>into the original piece of cable.
>
>As to the question of whether splitting the signal decreases the power,
>electricity isn't like a water pipe.
DC electricity is exactly like a water pipe. Pressure is voltage, gallons
per minute is current. Open the faucet and the pressure will go down and
water flow will go up. A.C. of course is another thing because of Eli and
ice man etc.
>Unless there's a LOAD at the end of
>a cable, why should it consume any power at all, except for the wire
itself?
Because the splitter is not a Tee! It must maintain impedance. Also the
wire does represent a load. Wire has impedance not to be confused with the
negligible DC resistance
Nick Manteen
On Wed, 4 Feb 1998 06:42:27 -0500, "David Winslow" <Da...@Winslow.mv.com> wrote:
>
>Michael Nolan wrote in message <6b5t9i$dlk$1...@falcon.inetnebr.com>...
>>I have a potential 'solution' to the math argument in the cable TV splitter
>>question.
>>
>>Could it be that it is the splitter itself that introduces a 3 dB signal
>>loss? As I recall, there are some resistive or capacitance components
>inside
>>a splitter that are there to reduce echo and ghosting problems, surely
>>these must sap up some of the signal.
>>
>>We were doing some testing of a security camera a while back, and needed
>>to connect two cables together to test a camera at an alternate location.
>>
>>I didn't have double 'F' connector handy, so we used a 3 way splitter.
>>There was very noticeable signal degradation compared to plugging the
>camera
>>into the original piece of cable.
>>
>>As to the question of whether splitting the signal decreases the power,
>>electricity isn't like a water pipe.
>
>DC electricity is exactly like a water pipe.
Good for you. A cable signal is not DC electricity. The remainder of your
example as been snipped as it has just been blown to smithereens.
Care to take another guess?
Jim Sokoloff
nm...@haven.net (Nick Manteen) writes:
Without even been read apparently...
> Care to take another guess?
Did you even read David's post? It seems pretty clear to me from the
remainder of his post that he understands that a cable signal is not
DC...
---Jim
David Winslow
Nick Manteen wrote in message <34e77428...@news.newsguy.com>...
>On Wed, 4 Feb 1998 06:42:27 -0500, "David Winslow" <Da...@Winslow.mv.com>
wrote:
>
>>
>>Michael Nolan wrote in message <6b5t9i$dlk$1...@falcon.inetnebr.com>...
>>>I have a potential 'solution' to the math argument in the cable TV
splitter
>>>question.
>>>
>>>Could it be that it is the splitter itself that introduces a 3 dB signal
>>>loss? As I recall, there are some resistive or capacitance components
>>inside
>>>a splitter that are there to reduce echo and ghosting problems, surely
>>>these must sap up some of the signal.
>>>
>>>We were doing some testing of a security camera a while back, and needed
>>>to connect two cables together to test a camera at an alternate location.
>>>
>>>I didn't have double 'F' connector handy, so we used a 3 way splitter.
>>>There was very noticeable signal degradation compared to plugging the
>>camera
>>>into the original piece of cable.
>>>
>>>As to the question of whether splitting the signal decreases the power,
>>>electricity isn't like a water pipe.
>>
>>DC electricity is exactly like a water pipe.
>
>Good for you. A cable signal is not DC electricity. The remainder of your
>example as been snipped as it has just been blown to smithereens.
>
>
>Care to take another guess?
It was not a guess, it was physics. The "DC" qualifier was there for a
reason. First you insult me, then you snip the rest of my post that
explains away your objection.
You got a grudge?
jjjb...@aol.com
Daman Grane wrote in message <34d621b8...@news.zippo.com>...
>On 2 Feb 1998 19:24:33 GMT, ra...@joesbar.cc.vt.edu () wrote:
>
>>Harry Mishugun (hm...@yulet.net) wrote:
>>: On 30 Jan 1998 21:28:59 GMT, ra...@joesbar.cc.vt.edu () wrote:
>>
>>: >Well, your math may need some help. A 2-way split gives you about
>>: >1/2 the signal level in each output (with a smidge of extra loss)a
>>: >Figure 50% for each 2-way split. A 4-way split just doubles the loss,
>>: >in other words 25% signal level.
>>
>>: Uh, your math is irrelevant here. 2-way splitters do not drop the
>>:signal by
>>: 50%. The original poster was correct with an approximate 3dB loss.
>>
>>I'm sorry, but my math is not irrelevant. My math is correct. A 3dB loss
>>is 50% loss.
>
>In the specific instance we are talking about it is more like 30%. Nice
> try.
Nope. The incoming signal is POWER, not voltage or current. The resulting
voltage and currents are functions of the receiving device. You can only
speak of voltages as signals in the special case where an independent
power supply is available, so that maximum signal power transfer is no
longer needed, and the signal can be processed as a voltage or current.
This is a common special case which occurs inside electronic equipment.
It is not the general case, however, and is not the case for broadcast or
cable signals. Here you must be aware that the signal is power since the
background noise which limits the signal to noise ratio is also a power
signal, and you do not want to degrade the ratio any further than it
already is. So, the splitter divides the signal POWER by 2 for a 3db
loss, the resulting dependent voltage level is reduced by 30%, for a 3db
reduction, and the resulting dependent current level is also reduced by
30%, for a 3db reduction. Do you find it significant at all that the
definitions for determing voltage and current db levels are defined in
terms of POWER? There is a reason why voltage db is given as 20log(V1/V2)
when generic db is defined as 10log(X1/X2). If you know this comes from
10log[(V1**2/RL)/(V2**2/RL)], that should give you a clue as to what the
signal is and what the dependent signal results are. >
>You cannot effectively apply dB loss to a split A/V signal. Just doesn't
> work
>that way.
It certainly does. The splitter is a one-to-one transformer dividing
the input power evenly. By the way, transformers do not have to be
one-to-one, and can boost either the output voltage or output current at
the expense of the other, but it must maintain a voltge-current product
consistent with incoming power. It cannot, of course, boost power levels.
-------------------==== Posted via Deja News ====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
hayespa
On Sat, 31 Jan 1998 07:41:19 -0500, Steve Goldman
<ste...@ix.netcom.com> wrote:
>Michael Nolan wrote:
>>
>> "Jim Sokoloff" <soko...@tiac.net: writes:
>>
>> :hm...@yulet.net (Harry Mishugun) writes:
>>
>> :> Uh, your math is irrelevant here. 2-way splitters do not drop the signal by
>> :> 50%. The original poster was correct with an approximate 3dB loss.
>>
>> :What the hell math are you doing? A 3db loss IS a 50%
>> :drop... (Actually, it's a 49.88% drop, but who's counting that
>> :closely?)
>>
>> :db is an expression of the ratio of power between two sources,
>> :defined as:
>>
>> :db = 10 log10 (P1 / P2)
>>
>> :Solving this (using math that is decidely not irrelevant) for -3db (a
>> :3db loss), we get P1/P2 = 10**(-0.3) or (drumroll, please): 0.501187
>>
>> I will admit that it has been over 25 years since I studied electrical
>> engineering, (and my less than brilliant grades in it were a major factor
>> in my decision to transfer to computer science) but according to Encyclopaedia
>> Britannica, when comparing the ratio of two electrical current, the decibel
>> formula is different than the formula used for comparing audio signals.
>>
>> According to my encyclopaedia, one decibel is equal to 20 times the common
>> logarithm of the ratio of the voltages or currents being compared.
>>
>> Accordingly, I would suggest that a 3dB loss in a splitter is equivalent to
>> about a 29 per cent signal loss, somewhat more than the 10% I suggested
>> earlier today, but somewhat less than 50%.
>>
>> But my math may still be flawed here, and I would defer to a more
>> current student.
>> --
>> Mike Nolan
>
>I wonder if the discrepancy is because decibels are intended to measure
>power, which is a function of either voltage or current squared.
>
>P=I^2*R or P=V^2/R
>
>So at a given impedance, a 29% reduction in current is a 50% reduction in
>power.
>
>Of course, as a chemical engineer, I really have no right to an opinion.
>
>Regards,
>
>Steve Goldman
You all forget that you are talking about MINISCULE voltage and
currents at RADIO FREQUENCIES. This seriously flaws the usual dB
ratio calculations. In addition, there is also a matching problem
involved as the antenna has to be "matched" with a specific
termination impedance to enable the maximum tranfer of the microvolts
of signal into the TV.
You would be well advised to install an RF (antenna) amplifier with
multiple outputs. Sufficient to feed all of your ACTIVE outlet points
and, from those locations add plug-in extensions to other locations
in the same room. The only visible part of the wiring would be a
short "tail" with a co-axial plug on it that plugs into the ACTIVE
outlet point to carry signal to the extended outlet point
Regards,
Peter Hayes