VGA Active/Powered Splitters (degradation?) (component to vga split too)..


M

markm75

I have a tricky situation I'm trying to determine whether to spend the
cash or not (and time)...

I have an xbox 360 with component output.. already I am taking the
component outputs and sending them to a component to VGA (powered)
converter box...

My goal is to take the signal and split it.. so I can have components
going to my main tv and the VGA signal going to my LCD in another
room...


Here is what I'm wondering:

1. In general.. VGA splitting, a powered device.. will I notice a
degradation of quality in the image if my cables are good and its rated
at 75 ohms?

2. My situation.. if I take the component cable.. use a component to
VGA cable.. run that VGA (really component but converted to a VGA
format) into this VGA splitter box... then I'll have 2 VGA outputs.. I
can then take the one VGA output and "re"convert it back to component
to send it to my component TV's inputs... I would take the other VGA
output and plug it into that component to VGA box (real computer VGA
signal output)... With this crazy setup.. will I notice reduction in
image quality on either the TV or the LCD? **the LCD doesnt have
component inputs, so I have to go with a converter in that case**

The vga splitter I was going to try was something like this:
http://www.geeks.com/details.asp?InvtId=VS-002&cm_mmc=Froogle-_-Monitors/LCDs-_-MonitorAccessories-_-VS-002

I've read that the bandwidth (150, 350 MHZ) isnt as important as the
Ohms rating.. not sure which is the case.. In my case the TV image on
each end would be something along the lines of a 720P size image or
about 1280 x 768 max resolution.


I guess the alternative is to just use a VGA swtich and manually select
one room or the other depending on which room I'm in...

Any tips or thoughts would be great..

Thanks
 
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B

Bob Myers

markm75 said:
1. In general.. VGA splitting, a powered device.. will I notice a
degradation of quality in the image if my cables are good and its rated
at 75 ohms?
With a decent "powered splitter" (distribution amplifier), and good
video cables, you should see little or no visible degradation of the
signal. "Decent" here is a factor mostly of proper input termination
impedance, and adequate bandwith or rise/fall time specs, etc..

2. My situation.. if I take the component cable.. use a component to
VGA cable.. run that VGA (really component but converted to a VGA
format)
Wait a sec - do you mean "component video" as in a TV-format
signal, in Y/C form, actually converted to RGB and/or upscaled
to a "PC" video timing, or just connecting the "component"
signals up via VGA connectors and cabling? ("Component"
is, unfortunately, one of those terms that covers a multitude
of possibilities.)
into this VGA splitter box... then I'll have 2 VGA outputs.. I
can then take the one VGA output and "re"convert it back to component
to send it to my component TV's inputs... I would take the other VGA
output and plug it into that component to VGA box (real computer VGA
signal output)... With this crazy setup.. will I notice reduction in
image quality on either the TV or the LCD? **the LCD doesnt have
component inputs, so I have to go with a converter in that case**
Since you're talking about a conversion here and not in the above,
I'm assuming that previously you meant the "component TV video
just mapped to VGA pins" case - right?
It's very hard to tell from that- the statement "supports 150 MHz
bandwidth" could mean anything from an amp that's perfectly
flat in response out to that frequency, or it might mean that someone
once range a 150 MHz video signal through and some sort of image
showed up on the monitor. For $12.50, I doubt that this is going to
be the equal of a truly top-notch distribution amp, but then, it IS only
$12.50 - might be worth a try.
I've read that the bandwidth (150, 350 MHZ) isnt as important as the
Ohms rating.. not sure which is the case..
Well, yes and no. Both are important to obtaining good results,
but the way most specs are presented to the consumer, it's virtually
impossible to get a really good idea as to how the unit actually
performs. Pretty much any product you find will CLAIM 75 ohm
inputs and some reasonable number for bandwidth - but as I said
above, those may or may not be adequate representations of how
the product will perform over the frequency range in question.

One other thing I should mention - if you're really serious about getting
the best performance in an analog video distribution system, and
especially if you're going to be dealing with fairly long cable runs,
VGA connectors and cabling are NOT the way to go. A far better
choice would be to route everything around using BNC connectors,
which pretty much force a decent-sized coaxial cable to be used for
the conductors. You can always put a VGA or whatever at the far
end, if need be.

Bob M.
 
M

markm75

See My comments mixed in below...


Bob said:
With a decent "powered splitter" (distribution amplifier), and good
video cables, you should see little or no visible degradation of the
signal. "Decent" here is a factor mostly of proper input termination
impedance, and adequate bandwith or rise/fall time specs, etc..



Wait a sec - do you mean "component video" as in a TV-format
signal, in Y/C form, actually converted to RGB and/or upscaled
to a "PC" video timing, or just connecting the "component"
signals up via VGA connectors and cabling? ("Component"
is, unfortunately, one of those terms that covers a multitude
of possibilities.)
Well the component to vga cable is something like this :
http://cgi.ebay.com/12FT-Component-to-VGA-cable-12_W0QQitemZ260064471508QQcmdZViewItem

Basically I'll be taking a progressive signal from the XBOX 360 and
converting the component format into VGA pins (as you mentioned)..

Then I'll run that "VGAized" connector into a VGA splitter box.. one of
the splits will go to an HDTV.. the other split will go into the
"component to VGA (computer signal vga) converter device".. this device
not only takes component cables but a "vga" cable as inputs..
outputting them to a VGA computer signal for my LCD in the other room..


Since you're talking about a conversion here and not in the above,
I'm assuming that previously you meant the "component TV video
just mapped to VGA pins" case - right?


It's very hard to tell from that- the statement "supports 150 MHz
bandwidth" could mean anything from an amp that's perfectly
flat in response out to that frequency, or it might mean that someone
once range a 150 MHz video signal through and some sort of image
showed up on the monitor. For $12.50, I doubt that this is going to
be the equal of a truly top-notch distribution amp, but then, it IS only
$12.50 - might be worth a try.


Well, yes and no. Both are important to obtaining good results,
but the way most specs are presented to the consumer, it's virtually
impossible to get a really good idea as to how the unit actually
performs. Pretty much any product you find will CLAIM 75 ohm
inputs and some reasonable number for bandwidth - but as I said
above, those may or may not be adequate representations of how
the product will perform over the frequency range in question.

One other thing I should mention - if you're really serious about getting
the best performance in an analog video distribution system, and
especially if you're going to be dealing with fairly long cable runs,
VGA connectors and cabling are NOT the way to go. A far better
choice would be to route everything around using BNC connectors,
which pretty much force a decent-sized coaxial cable to be used for
the conductors. You can always put a VGA or whatever at the far
end, if need be.
Long runs.. would 35 feet be considered a long run.. as this setup is
only temporary (i think).. I will probably end up going with the pure
VGA cable for the 360 once I get a projector that takes a VGA signal..
at that point I'd still use the VGA splitter, if the quality doesnt
diminish, but I'll have a 35 foot run instead of say a 10 foot...

If so.. if i need to go bnc.. what is an example of such.. is it a
basic "cable" coax cable.. with BNC connectors on each end.. somehow
converting to either VGA or component?

Thanks for the help
 
B

Bob Myers

markm75 said:
OK - so from that, it looks like you'e taking a progressive-scan,
RGB, TV-format set of video signals, and simply connecting t
hem up via VGA connectors. Got it. You're not really converting
the format here, you're just changing from separate connectors
carrying the individual RGB signals to having them all on the VGA.

Just as an aside - if you can find a distribution amp that will handle
the separate RGB "component" lines in that form, you'd probably
get better results using it, and then doing the conversion to the
VGA connector at the very end (if you have to, to hook up to
a monitor with only a VGA input). Those separate connectors
are much more signal-friendly than the VGA.
Then I'll run that "VGAized" connector into a VGA splitter box.. one of
the splits will go to an HDTV.. the other split will go into the
"component to VGA (computer signal vga) converter device".. this device
not only takes component cables but a "vga" cable as inputs..
outputting them to a VGA computer signal for my LCD in the other room..
Again, my preference would be keeping these signals in
separate "component" form (meaning separate coaxial cables
with decent connectors) as long as possible before combining
them onto a VGA connector. Do you get the impression I'm not
a big fan of the VGA connector? :)

Long runs.. would 35 feet be considered a long run..
Yes - that's more than long enough to be concerned about
losses in the cable, and significant "ghosting" if the cables aren't
terminated in the correct impedance.

You'd asked about BNC connectors - these are most commonly
used on high-end consumer or pro video equipment, handling
separate "component" style video. (All "component" really means
is that multiple signals which would otherwise be combined into a
single, "composite" signal are maintained as physically separate
lines - for instance, RGB or even Y/C signals vs. the "all on one
conductor" sort of "composite" video.) This is what a BNC connector
looks like:

http://www.dayton-wright.com/BNC-Connector-Set-08.jpg

This is probably the best connector, in terms of signal quality,
that's in common use in video systems. Especially when mated with
a decent coaxial cable (it's not quite this easy, but in general
a fatter coax is a better one here).

Bob M.
 
M

markm75

SMCB again:)

Bob said:
OK - so from that, it looks like you'e taking a progressive-scan,
RGB, TV-format set of video signals, and simply connecting t
hem up via VGA connectors. Got it. You're not really converting
the format here, you're just changing from separate connectors
carrying the individual RGB signals to having them all on the VGA.

Just as an aside - if you can find a distribution amp that will handle
the separate RGB "component" lines in that form, you'd probably
get better results using it, and then doing the conversion to the
VGA connector at the very end (if you have to, to hook up to
a monitor with only a VGA input). Those separate connectors
are much more signal-friendly than the VGA.
Do you have an example of such a "distribution amp".. forgive me as
I've never had a need to go this advanced with cabling till now :)



Again, my preference would be keeping these signals in
separate "component" form (meaning separate coaxial cables
with decent connectors) as long as possible before combining
them onto a VGA connector. Do you get the impression I'm not
a big fan of the VGA connector? :)



Yes - that's more than long enough to be concerned about
losses in the cable, and significant "ghosting" if the cables aren't
terminated in the correct impedance.
Splitters and two tv's aside.. would a 35 foot run be considered a long
run even for a Component Cable? I've seen mixed notes on that.. some
say 50 feet would be "long" etc.. But I wasnt sure if they meant
component or for VGA or both...
You'd asked about BNC connectors - these are most commonly
used on high-end consumer or pro video equipment, handling
separate "component" style video. (All "component" really means
is that multiple signals which would otherwise be combined into a
single, "composite" signal are maintained as physically separate
lines - for instance, RGB or even Y/C signals vs. the "all on one
conductor" sort of "composite" video.) This is what a BNC connector
looks like:

http://www.dayton-wright.com/BNC-Connector-Set-08.jpg

This is probably the best connector, in terms of signal quality,
that's in common use in video systems. Especially when mated with
a decent coaxial cable (it's not quite this easy, but in general
a fatter coax is a better one here).
So.. I'm still a little confused.. or maybe not.. but the BNC connector
set would go on both ends of a Coax cable.. I forget the gauge etc..
but for the coax I ran through my house it was considered good enough
for Digital Cable.. I forget what the terminology was on its gauge.. a
4 or someother indicator. or was it RG4 or RG6 perhaps..

Thanks again for all the help on this topic :)
 
B

Bob Myers

markm75 said:
Do you have an example of such a "distribution amp".. forgive me as
I've never had a need to go this advanced with cabling till now :)
Google is your friend...try "VGA distribution amplifier," and you'll
find lots of products and sources; here's just one of them:

http://www.ramelectronics.net/html/Dist-amps.html


Splitters and two tv's aside.. would a 35 foot run be considered a long
run even for a Component Cable? I've seen mixed notes on that.. some
say 50 feet would be "long" etc.. But I wasnt sure if they meant
component or for VGA or both...
Yes, certainly. 35 feet is a "long run" for any signal in the
frequency range we're talking about. Basically, "long" in cable
terms is best considered in terms of wavelength - if the
length of the cable run is a significant fraction of the signal
wavelength, it's a "long" cable. For a progressive-scan
480-line video signal, we're talking about pixels at a rate
of around 25 MHz or more - and the wavelength of a 25
MHz signal is about 12 meters, or just about 40 feet. So
a 35 foot cable should definitely be considered "long."

Don't get too hung up on this "component" vs. "VGA"
distinction - actually, VGA connectors carry what have to
be consider "component" video signals, since they're
three separate (RGB) signals that just happen to be on
a common connector. One example of what the TV world
calls "component" video is also separate RGB signals, but
they're carried on three physically separate connectors.
Electrically, these are the same - it's just a difference in the
physical packaging.
So.. I'm still a little confused.. or maybe not.. but the BNC connector
set would go on both ends of a Coax cable.. I forget the gauge etc..
Right. Or you can also find cable assemblies which have 3 or more
BNC on separate coaxes at one end, but the cables all come together
to a single VGA connector at the other.
but for the coax I ran through my house it was considered good enough
for Digital Cable.. I forget what the terminology was on its gauge.. a
4 or someother indicator. or was it RG4 or RG6 perhaps..
The number that follows the "RG" on coax designations isn't a
gauge; it doesn't directly relate to the size of the conductor inside.
You CAN tell the gauge, and other things, from the RG number,
but the number itself isn't a size indicator - you have to look the
information up in a table of specifications. The "RG" designation
itself comes from a very old set of military specifications (it
supposedly stands for "Radio Guide"). RG-6, for instance, simply
means a 75 ohm coaxial cable with an 18-gauge center conductor.
It's fairly common in video use, but then so is RG-59, a smaller
75-ohm cable (and "smaller" generally translates to "more lossy").
But just to show that the number itself doesn't mean much, there's
a rarely-seen-these-days 75 ohm cable larger than RG-6- it's called
RG-11, which has a 14-gauge center conductor! It's important to
note that there isn't a whole lot of information beyond conductor
size and impedance you can get from just knowing the RG number.
It is definitely not the case, for example, that "RG-6 is better shielded
than RG-59" or other such things that you might here. You might
be able to say that about a particular example of those two cables,
but the RG number itself does not ensure this.

Both RG-59 and RG-6 can be used with BNC connectors, given
the right BNCs (you have to choose the connector with the right
sort of "barrel" to fit the cable diameter); a good version of either
will likely work well in your application. RG-6, though, being
significantly larger in overall diameter, would be difficult to use -
IF you have to have a VGA on one end of the cable assembly.
Bringing 3 RG-6's into a VGA would be tricky.

Bob M.
 
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M

markm75

Bob said:
Google is your friend...try "VGA distribution amplifier," and you'll
find lots of products and sources; here's just one of them:

http://www.ramelectronics.net/html/Dist-amps.html
Wow.. the price range is a bit high on such devices .. $350 and up it
would seem.. at least from Ramelectronics.. which I have bought from
before. :)

Yes, certainly. 35 feet is a "long run" for any signal in the
frequency range we're talking about. Basically, "long" in cable
terms is best considered in terms of wavelength - if the
length of the cable run is a significant fraction of the signal
wavelength, it's a "long" cable. For a progressive-scan
480-line video signal, we're talking about pixels at a rate
of around 25 MHz or more - and the wavelength of a 25
MHz signal is about 12 meters, or just about 40 feet. So
a 35 foot cable should definitely be considered "long."

I had noted that someone on one of the AVSforum threads said they ran
component, dvi, and hdmi about 35 feet and didnt have any problems, but
I guess perhaps he isnt "aware" he is having problems or didnt try
shorter runs to compare the quality.


Don't get too hung up on this "component" vs. "VGA"
distinction - actually, VGA connectors carry what have to
be consider "component" video signals, since they're
three separate (RGB) signals that just happen to be on
a common connector. One example of what the TV world
calls "component" video is also separate RGB signals, but
they're carried on three physically separate connectors.
Electrically, these are the same - it's just a difference in the
physical packaging.


Right. Or you can also find cable assemblies which have 3 or more
BNC on separate coaxes at one end, but the cables all come together
to a single VGA connector at the other.


The number that follows the "RG" on coax designations isn't a
gauge; it doesn't directly relate to the size of the conductor inside.
You CAN tell the gauge, and other things, from the RG number,
but the number itself isn't a size indicator - you have to look the
information up in a table of specifications. The "RG" designation
itself comes from a very old set of military specifications (it
supposedly stands for "Radio Guide"). RG-6, for instance, simply
means a 75 ohm coaxial cable with an 18-gauge center conductor.
It's fairly common in video use, but then so is RG-59, a smaller
75-ohm cable (and "smaller" generally translates to "more lossy").
But just to show that the number itself doesn't mean much, there's
a rarely-seen-these-days 75 ohm cable larger than RG-6- it's called
RG-11, which has a 14-gauge center conductor! It's important to
note that there isn't a whole lot of information beyond conductor
size and impedance you can get from just knowing the RG number.
It is definitely not the case, for example, that "RG-6 is better shielded
than RG-59" or other such things that you might here. You might
be able to say that about a particular example of those two cables,
but the RG number itself does not ensure this.

Both RG-59 and RG-6 can be used with BNC connectors, given
the right BNCs (you have to choose the connector with the right
sort of "barrel" to fit the cable diameter); a good version of either
will likely work well in your application. RG-6, though, being
significantly larger in overall diameter, would be difficult to use -
IF you have to have a VGA on one end of the cable assembly.
Bringing 3 RG-6's into a VGA would be tricky.
Ah I see.. so you cant just use 1 single line of COAX and have the
"Component bncs" on the other end.. I'd have to run 3 seperate coax
lines.. so you are saying I should choose a smaller gauge to make
things simpler.

So at this point my options for this long of a run would be the dist.
amplifier or run the coax cables..

You dont think very high end quality VGA or components or even dvi,
then converting to VGA would make a difference then, especially since
I'll probably be dealing with 720p signals most of the time at that
distance.


Cheers
 
B

Bob Myers

markm75 said:
Wow.. the price range is a bit high on such devices .. $350 and up it
would seem.. at least from Ramelectronics.. which I have bought from
before. :)
Those were just an example, but yes, it does cost to get
quality equipment. There are amps out there for less which may
do the job, or may not. I don't endorse or criticize any particular
make or model here.
I had noted that someone on one of the AVSforum threads said they ran
component, dvi, and hdmi about 35 feet and didnt have any problems, but
I guess perhaps he isnt "aware" he is having problems or didnt try
shorter runs to compare the quality.
Or perhaps this person bought quality cabling, etc., to begin
with. I have, in the past, run analog RGB signals carrying
1280 x 1024 @ 75 Hz for over 200 feet without any buffer,
amplifier, etc. - just some very carefully-chosen cable with
carefully-chosen (and attached!) connectors. There's no
hard and fast limit beyond which things just won't work at
all (well, not in most cases with respect to video interface -
there are some, mostly digital types, in which the protocol
itself establishes a pretty fixed limit.
Ah I see.. so you cant just use 1 single line of COAX and have the
"Component bncs" on the other end..
No, with coax, it's one signal per line. Your "component"
video in this case is separate red, green, and blue signals,
presumably with the sync signals being carried on the green
video (which is the standard place to put them). If not, then
there has to be at least one more line to carry the syncs
(running "VGA" this way would require two extra lines,
because in that system the syncs are completely separate).
But since this is "TV" video, I'm assuming it's sync-on-green.

I'd have to run 3 seperate coax
lines.. so you are saying I should choose a smaller gauge to make
things simpler.
Well, a smaller cable makes for an easier connection when you
get to the VGA connector, since there's only so much room
there. A smaller cable also generally means more loss, so it's
a question of what you can tolerate there. The ideal would be
to run a low-loss cable with BNCs on both ends for the bulk of the
distance, and even if that cable is the size of garden hose it wouldn't
be that big a deal - you'd be hooking up a short BNC-to-VGA
cable assembly at the far end.

So at this point my options for this long of a run would be the dist.
amplifier or run the coax cables..
You will need a distribution amplifier to properly split the signal
without loss if you're going to be feeding two or more displays
anyway. The best set-up, if you can do it, would be to keep the
signal in "component" form on separate coaxes for a short run
to the distribution amp, which could be BNCs in and out - then
the above long runs (coax with BNCs on each end) to the displays,
and only have a short BNC-to-VGA assembly on the far end if
needed for a particular display.

You dont think very high end quality VGA or components or even dvi,
then converting to VGA would make a difference then, especially since
I'll probably be dealing with 720p signals most of the time at that
distance.
Again, in your case "converting to VGA" just means combining the
three separate signals onto a VGA connector - there's no real signal
conversion going on here. And given that the VGA isn't all that great
a high-frequency connector, I would avoid it if I could until the end
of the run.

DVI is a somewhat different story, depending on whether you're talking
the analog or digital parts of that connector. (A DVI-I supports both
digital and analog video; a DVI-D is analog only.) The digital signal
will be relatively immune to noise, etc., and can be run over a 30-35
foot distance with the right cabling (but the right cabling in that case
could be pretty expensive). It won't go much beyond that, though.
The analog side of a DVI-I carries signals which are identical to those
on a VGA - it's just a better analog connector. Again, though, it will
be the quality of the cabling that determines the success of a run of this
length, even with a DVI-I.

Bob M.
 
M

markm75

Bob said:
Those were just an example, but yes, it does cost to get
quality equipment. There are amps out there for less which may
do the job, or may not. I don't endorse or criticize any particular
make or model here.


Or perhaps this person bought quality cabling, etc., to begin
with. I have, in the past, run analog RGB signals carrying
1280 x 1024 @ 75 Hz for over 200 feet without any buffer,
amplifier, etc. - just some very carefully-chosen cable with
carefully-chosen (and attached!) connectors. There's no
hard and fast limit beyond which things just won't work at
all (well, not in most cases with respect to video interface -
there are some, mostly digital types, in which the protocol
itself establishes a pretty fixed limit.

The one person said they bought cabling from monoprice or monoprice
brand.. they said they guessed it was 2nd from the top of that brand of
component cable.

I did run across this from one site:
http://www.bluejeanscable.com/articles/componentvideocable.htm
"Over reasonable run lengths (say, under 100 feet), these losses are
not really significant so long as one is dealing with a cable having a
reasonably-sized center conductor (say, 22 AWG or larger)"

I think they sell their own stuff, so they could be bias :)



No, with coax, it's one signal per line. Your "component"
video in this case is separate red, green, and blue signals,
presumably with the sync signals being carried on the green
video (which is the standard place to put them). If not, then
there has to be at least one more line to carry the syncs
(running "VGA" this way would require two extra lines,
because in that system the syncs are completely separate).
But since this is "TV" video, I'm assuming it's sync-on-green.



Well, a smaller cable makes for an easier connection when you
get to the VGA connector, since there's only so much room
there. A smaller cable also generally means more loss, so it's
a question of what you can tolerate there. The ideal would be
to run a low-loss cable with BNCs on both ends for the bulk of the
distance, and even if that cable is the size of garden hose it wouldn't
be that big a deal - you'd be hooking up a short BNC-to-VGA
cable assembly at the far end.

I searched around on this.. it seems alot of people would just use the
RG59 due to ease and risk the loss part I guess.. I'm still hoping
I'll be lucky and just get a decent run of component and wont need to
do that (unfortunately my budget is tight.. i was hoping to keep the
cabling under $200).

I also found notes stating that one should make sure its solid copper,
not copper coated.. center being solid or stranded wire.. and not rated
for TV or satellite (uses conductors not all copper).
You will need a distribution amplifier to properly split the signal
without loss if you're going to be feeding two or more displays
anyway. The best set-up, if you can do it, would be to keep the
signal in "component" form on separate coaxes for a short run
to the distribution amp, which could be BNCs in and out - then
the above long runs (coax with BNCs on each end) to the displays,
and only have a short BNC-to-VGA assembly on the far end if
needed for a particular display.
Sorry on the reiteration part here.. but I guess it could be hit or
miss if I try an active splitter (at least 70MHZ or more) ranging in
price from $15 to say $50...

But what if I skip the active splitter and just do the switch.. a
simple selector.. a 2 in 1 (either component or VGA, active based)..
I've read many blogs where folks have done this without any problems
(and some who said to stay away from X brand, etc).

Some mentioned this one as effective:
http://www.avlinx.com/index.cfm?zone=953C005085A28527354689125248
(granted not 2 in 1)...

I may do this anyway.. I have a receiver .. an Onkyo.. not very old..
has 3 components on it.. one out.. but I have trouble with Lipsync
issues.. I'm assuming its due to the video switching it provides (do
these receivers do any kind of amplification that you know of?).. so
perhaps taking all the components to the outside with a selector may
help with that as well... although, once I have an HD-DVD drive, I'll
be using HDMI for sure, though in the case of my Comcast HD box.. I
think component works just as well (many said there was no difference
in quality)...

What would be ideal.. is if the xbox had an HDMI connector.. then I'd
just buy a 3way HDMI switch (a decent one).. or if there was a way to
take the component and convert it to DVI/HDMI (but the prices are
somewhat high on those)...

If only this was much simpler :)

ps.. how did you find my post.. I'm curious.. I usually google others
for info.. or do you have alerts set in this group.. never asked till
now.. so i'm curious.. anyways thanks for all the great input and
help.. i usually work with more software and pure OS related hardware..
rather than cabling, specifically the video end :)
 
B

Bob Myers

markm75 said:
I did run across this from one site:
http://www.bluejeanscable.com/articles/componentvideocable.htm
"Over reasonable run lengths (say, under 100 feet), these losses are
not really significant so long as one is dealing with a cable having a
reasonably-sized center conductor (say, 22 AWG or larger)"
That's one of those things which may be true in the majority
of cases, although center-conductor size isn't the only thing
which determines cable losses at high frequencies. Loss
also isn't the only concern here - again, proper termination
impedance is the other big issue, since on long runs "ghosting"
can become a serious problem.

I searched around on this.. it seems alot of people would just use the
RG59 due to ease and risk the loss part I guess.. I'm still hoping
I'll be lucky and just get a decent run of component and wont need to
do that (unfortunately my budget is tight.. i was hoping to keep the
cabling under $200).

I also found notes stating that one should make sure its solid copper,
not copper coated.. center being solid or stranded wire.. and not rated
for TV or satellite (uses conductors not all copper).
It's OK advice as far as it goes, although I would have no
issues with trying a stranded center conductor here. Beyond
that, well, you'd really want to look at the actual cable
specifications rather than trying to guess what's best based on
the cable construction.
Sorry on the reiteration part here.. but I guess it could be hit or
miss if I try an active splitter (at least 70MHZ or more) ranging in
price from $15 to say $50...
Again, you can try it - if it doesn't meet you needs, maybe you
could return it. At worst, you'd be out the $15-50 or maybe
you'd find some other use for the thing.
But what if I skip the active splitter and just do the switch.. a
simple selector.. a 2 in 1 (either component or VGA, active based)..
I've read many blogs where folks have done this without any problems
(and some who said to stay away from X brand, etc).
A switch can also work well if (a) you have no real need to
drive multiple displays at the same time, and (b) the switch is
again a good-quality unit. Poor-quality switchgear will be a
source of impedance problems, and therefore ghosting.
ps.. how did you find my post.. I'm curious..
I regularly read the comp.sys.ibm.pc.hardware.video newsgroup,
which is where this discussion is showing up.

Bob M.
 
M

markm75

Bob said:
That's one of those things which may be true in the majority
of cases, although center-conductor size isn't the only thing
which determines cable losses at high frequencies. Loss
also isn't the only concern here - again, proper termination
impedance is the other big issue, since on long runs "ghosting"
can become a serious problem.



It's OK advice as far as it goes, although I would have no
issues with trying a stranded center conductor here. Beyond
that, well, you'd really want to look at the actual cable
specifications rather than trying to guess what's best based on
the cable construction.


Again, you can try it - if it doesn't meet you needs, maybe you
could return it. At worst, you'd be out the $15-50 or maybe
you'd find some other use for the thing.


A switch can also work well if (a) you have no real need to
drive multiple displays at the same time, and (b) the switch is
again a good-quality unit. Poor-quality switchgear will be a
source of impedance problems, and therefore ghosting.


I regularly read the comp.sys.ibm.pc.hardware.video newsgroup,
which is where this discussion is showing up.

Bob M.
I cant recall if I had this in my previous posts.. I dont think I got
specific though:

Have you ever used or know of anyone who has tried a device like this:

http://www.datapro.net/products/CSV-955A.html

I've just received it.. I am going to test it tonight...

This was my other solution, should I not end up doing VGA with my 360
once I get my projector . This lets me take the component signal and
output it to a PC vga type signal on the PC LCD..

This is where, before, I said that I'd convert the pins to vga, then
use a switch/splitter to split that style connector.. then on the other
side of the splitter or switch.. this device would be used for one
output of the switch.. sending a PC VGA signal (using this transcoder),
while the other port would get converted back to component from the vga
pins.

I've read that you definitely need an active transcoder to get good
quality.. this was the only one that met the bill so to speak.. but
seeing will be believing. So tonight I'll try it, without a splitter,
then I'll try the "Radio shack special" splitter or switch and see how
the image compares when in use (of course later on I'll be dealing with
the cable length issues, once I finally get that projector :)
 
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B

Bob Myers

markm75 said:
Have you ever used or know of anyone who has tried a device like this:

http://www.datapro.net/products/CSV-955A.html

I've just received it.. I am going to test it tonight...
I'm not familiar with that specific device, no. From the looks of
the thing, what it is probably doing is simply stripping the syncs
off the green video, and putting them out as separate TTL sync
on the VGA connector (fewer and fewer VGA inputs are happy
with sync-on-green video). It's not really doing anything by way
of a "transcoding" as I would use the term beyond that, and I don't
even know if it's buffering (i.e., has a unity-gain amplifier inside)
the signal before shipping it out to the VGA. All I can really
say is - let us know how it turns out.

Bob M.
 
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M

markm75

Bob said:
I'm not familiar with that specific device, no. From the looks of
the thing, what it is probably doing is simply stripping the syncs
off the green video, and putting them out as separate TTL sync
on the VGA connector (fewer and fewer VGA inputs are happy
with sync-on-green video). It's not really doing anything by way
of a "transcoding" as I would use the term beyond that, and I don't
even know if it's buffering (i.e., has a unity-gain amplifier inside)
the signal before shipping it out to the VGA. All I can really
say is - let us know how it turns out.

Bob M.
Well this device has worked out fairly well.. its not as good as the
vga cable for the 360.. at least in terms of filling the screen.. on
the left side of my LCD you can see about a 1/2 or less black vertical
bar (far left).. nothing I've tried has gotten rid of it... I suppose
it has something to do with taking a 720p widescreen image and
attempting to fit it to a 4:3 screen. The images look great though.

I then found a splitter that seems to work.. I really just wanted an
autosensing or manual vga switch, but I cant seem to find any.. at
least none that are under $100...

The splitter is working out ok so far, I tried a test.. first doing the
cable without splits then hooking it up.. though a lag of about 3
minutes b4 i could get back in there to see the difference, I really
couldnt see one to my surpise. No change in brightness etc.. Although
at one point I had hooked up the 2nd connection to the splitter and
tried it.. the brightness levels dropped.. so I tried switching the
ports (its a 4 porter).. to one closer to the other port and then the
levels were back to "normal".

Ill have to have someone try both ways in the other room while watching
the screen to verify that there is no change in quality but it looks
good so far. Its a Aten 250MHZ switch.. I believe that is plenty of
bandwidth too.. even for 1080p if I ever can utilize it (2 ports used).

Mark
 

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