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Single CAT5 cable for data and VGA signal?
- Thread starter sunil5
- Start date
youcandoit
Technical User
i would say no too. Ethernet uses two pairs orange and green. do you have some device to run vga over 2 pair? Name the device so I can look at it. or try it see if it works
- Thread starter
- #4
This is theoretically possible. There are adapters that take a normal CAT-5 cable with "RJ-45" jacks and provide 2 jacks at each end. These adapters use the two unused pairs in a typical ethernet wiring scheme to provide a second ethernet path.
With such adapters, you could then run Ethernet over the first set, and VGA over the second set, using those VGA-CAT-5 adapters one sees in the gadget catalogs.
As Stu points out, you may get interference - it's possible the video signals will mess up the ethernet. But I disagree that you could damage something, as long as you make sure you don't confuse the Ethernet with the Video. At worst, you'll have a degraded picture, or unreliable network. But it shouldn't hurt to try.
To prevent mistakes, setup one complete path first. For example, establish the Ethernet link first, to prevent accidently connecting a VGA source to an ethernet port.
With such adapters, you could then run Ethernet over the first set, and VGA over the second set, using those VGA-CAT-5 adapters one sees in the gadget catalogs.
As Stu points out, you may get interference - it's possible the video signals will mess up the ethernet. But I disagree that you could damage something, as long as you make sure you don't confuse the Ethernet with the Video. At worst, you'll have a degraded picture, or unreliable network. But it shouldn't hurt to try.
To prevent mistakes, setup one complete path first. For example, establish the Ethernet link first, to prevent accidently connecting a VGA source to an ethernet port.
- Thread starter
- #6
jlshelton,
That's what I read on a description of a particular (lost the link now!)- but I'm no expert on cables, so I thought I'd throw out the question to you guys.
Of course ideally, I would run each signal on it's own cable but the network cabling has been done a long time ago with only single point connections (which are currently used by PCs).
P.S. Any products that you could recommend? I'm in the UK.
That's what I read on a description of a particular (lost the link now!)- but I'm no expert on cables, so I thought I'd throw out the question to you guys.
Of course ideally, I would run each signal on it's own cable but the network cabling has been done a long time ago with only single point connections (which are currently used by PCs).
P.S. Any products that you could recommend? I'm in the UK.
AdmanOK
MIS
- Mar 5, 2001
- 412
I have used some ATEN brand CAT5 VGA extenders before, and even under optimal conditions the quality is mediocre at best. I was curious if something like this would work so I just went and did some experimenting. I found that you can get a picture to display at the remote end, but it is very dim and not particularly clear. Without spending too much time checking, it appeared that the unit broke the VGA signal out into it's Red Green and Blue components and sent each of them down an individual pair. I was able to disconnect pins 7 & 8 without any affect on the image. This would indicate that to get the full brightness picture would require six conductors, leaving only two for the ethernet portion, which would not work. If you trully require it to run on one cable run you could check out some of the single pair network devices, either the home "phone line" networking gear, or if you want something more serious look at Cisco's LRE equipment. I have used LRE over all sorts of single pair copper connections and it works like a charm... kind of pricey for one point to point application though, the lowest buy in point for the head end is an 8 port version.
youcandoit
Technical User
what about wifi 802.11? and just use the cat5 for vga.
- Thread starter
- #11
Wireless would be too slow for anything these computers need to do- i've tried it.
I have considered IP KVM devices but the best way of course would be to try things out to be sure.
skip555- if it were possible to do this (in this situation) then the post would be non-existant (!)
Thanks for all your responses.
I have considered IP KVM devices but the best way of course would be to try things out to be sure.
skip555- if it were possible to do this (in this situation) then the post would be non-existant (!)
Thanks for all your responses.
franklin97355
Technical User
Sunil, sounds like you're out of luck. Without some sort of media converters you will likely not get high speed, reliable network connections.
The passage of video and data on digital wiring can be done fairly
easily if you digitize the video AND if your network supports 'isochronous'
real-time data transfer. Alas, Ethernet doesn't necessarily support real-time
data (thus, VoIP is still somewhat tricky, IP video is flaky).
The gamers that share dungeons over IP use shorthand (the IPX protocol),
not really sharing the full video stream.
Firewire, aka iLink, aka 1394b, is intended for this kind of thing.
Firewire DOES support isochronous, and there's a variant of the standard
that works on Cat5 twisted pairs. It's common (in the Macintosh world)
to use Firewire ports for TCP/IP, too, which would cover the data needs of most computers, and would share with a video stream.
The bad news: that Cat5 element of the standard requires Firewire to slow
to 100 Mbit, and I've never actually seen it implemented. Firewire ports are usually 400 Mbit, or 800/400 Mbit. Also, the video
stream for digital transmission is typically HD video, which requires some
hardware to encode (not easy to splice in to a VGA channel). Both ends of the
channel are Firewire (so it can't go to or through an Ethernet switch any more). That means you'd get TCP/IP connection between the two, but
one would have to host bridge software to connect to Ethernet for any kind of
network beyond those first two machines.
No one else has mentioned it (so I guess I will); the same common-mode
connection that provides Ethernet power without disturbing the differential
mode network signals, can be used to make an additional 'wire' of each of the
(four, presumably) pairs in a Cat5 cable. This would amount to an unshielded, untwisted quad of not-well-specified wiring, and one could
conceivably send signals through it. It would radiate badly, and the crosstalk would be significant, and it requires wiring to the central tap of the Ethernet
interface's magnetics (to the center tap of the transformer output).
That's pretty ugly.
Another non-Ethernet way to proceed, would be to use three pairs to send
RGB video signals (with suitable 75 ohm VGA/ 120 ohm baluns and
amplification), and the fourth for a modem connection (alas, probably that'd be limited to 33 kbaud unless you can get some pricey DSL modems
that can really use the cable bandwidth). It used to be easy to get sync-on-green from a video card, and maybe it still is. The receiver would have to regenerate
the sync signals in addition to buffering the balanced RGB. It's not gonna be
a simple wire solution.
easily if you digitize the video AND if your network supports 'isochronous'
real-time data transfer. Alas, Ethernet doesn't necessarily support real-time
data (thus, VoIP is still somewhat tricky, IP video is flaky).
The gamers that share dungeons over IP use shorthand (the IPX protocol),
not really sharing the full video stream.
Firewire, aka iLink, aka 1394b, is intended for this kind of thing.
Firewire DOES support isochronous, and there's a variant of the standard
that works on Cat5 twisted pairs. It's common (in the Macintosh world)
to use Firewire ports for TCP/IP, too, which would cover the data needs of most computers, and would share with a video stream.
The bad news: that Cat5 element of the standard requires Firewire to slow
to 100 Mbit, and I've never actually seen it implemented. Firewire ports are usually 400 Mbit, or 800/400 Mbit. Also, the video
stream for digital transmission is typically HD video, which requires some
hardware to encode (not easy to splice in to a VGA channel). Both ends of the
channel are Firewire (so it can't go to or through an Ethernet switch any more). That means you'd get TCP/IP connection between the two, but
one would have to host bridge software to connect to Ethernet for any kind of
network beyond those first two machines.
No one else has mentioned it (so I guess I will); the same common-mode
connection that provides Ethernet power without disturbing the differential
mode network signals, can be used to make an additional 'wire' of each of the
(four, presumably) pairs in a Cat5 cable. This would amount to an unshielded, untwisted quad of not-well-specified wiring, and one could
conceivably send signals through it. It would radiate badly, and the crosstalk would be significant, and it requires wiring to the central tap of the Ethernet
interface's magnetics (to the center tap of the transformer output).
That's pretty ugly.
Another non-Ethernet way to proceed, would be to use three pairs to send
RGB video signals (with suitable 75 ohm VGA/ 120 ohm baluns and
amplification), and the fourth for a modem connection (alas, probably that'd be limited to 33 kbaud unless you can get some pricey DSL modems
that can really use the cable bandwidth). It used to be easy to get sync-on-green from a video card, and maybe it still is. The receiver would have to regenerate
the sync signals in addition to buffering the balanced RGB. It's not gonna be
a simple wire solution.
You only need two wires to transmit video over ethernet with and RCA balum connection on each side, it is also possible to run the power over the same line. Modern computer networks use all 4 pairs of wires to transmit data, if you use less your degrading yourself to cat3. Meaning slowing things down.
Is it theorectically possible with no interference? Ya.
Should you do it with no expierience? No.
Probably not worth the possible hassels and risks unless your into fixing alot of unknown headaches.
Run an IP camera, Run another line.
Is it theorectically possible with no interference? Ya.
Should you do it with no expierience? No.
Probably not worth the possible hassels and risks unless your into fixing alot of unknown headaches.
Run an IP camera, Run another line.
You only need two wires to transmit video over ethernet with and RCA balum connection on each side."
A VGA monitor signal IS NOT composite video that can be transmitted over a single pair with or without baluns. A VGA signal will at minimum require three signals (RGB) each using a pair. There are also two sync signals on a standard VGA connector.
I am not aware of any VGA "extenders" that will run on two pairs.
A VGA monitor signal IS NOT composite video that can be transmitted over a single pair with or without baluns. A VGA signal will at minimum require three signals (RGB) each using a pair. There are also two sync signals on a standard VGA connector.
I am not aware of any VGA "extenders" that will run on two pairs.
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