What aspects of a DVI switch (KVM for example) would affect its ability to
handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)?
I'm curious why there are so many DVI switches that have a 1600 x 1200 limit
and can't do 1920 x 1200.
1920x1200 (WUXGA) is a single link format. Single link can go all the way
up
to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible)
format
would also be doable on single link. Dual link could go up to 2960x1850.
To get my Samsung 20" 1280 * 960 I had to place a special order;although myÏ said:In alt.engineering.electrical Bob Myers <[email protected]>
wrote:
| | \
|>
|> 1920x1200 (WUXGA) is a single link format. Single link can go all the
way
|> up
|> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible)
|> format
|> would also be doable on single link. Dual link could go up to
2960x1850.
|
| Well, at least per the pixel clock limits on both single- and dual-link
| DVI, they sure could. The problem is, though, that the DVI standard
| never included a decent compliance certification test, nor is there any
| good spec on cabling, switches, and the like that would truly ensure
| that you can run full rates over any given comibination of such things.
| So as you approach the top-end clock spec, some will work, and
| some may not.
Here's another one I found. It has a _higher_ resolution limit
(1920x1440)
but it has some suspicious words in the tech specs saying "This products
is
not intended for use with Widescreen displays".
http://www.startech.com/item-specs/SV421DVI-4-Port-StarView-DVI-KVM-Switch.aspx
So what could that possibly mean? Could it really be that these switches
are
messing around with the EDID data or other parameters affected by the
specific
geometry, and are not designed for the 16:10 geometries?
--
| In article <[email protected]>, (e-mail address removed)
| says...
|> What aspects of a DVI switch (KVM for example) would affect its ability to
|> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)?
|> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit
|> and can't do 1920 x 1200.
|
| What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get
| the refresh rate you're looking for at 1920x1200.
1920x1200 (WUXGA) is a single link format. Single link can go all the way up
to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) format
would also be doable on single link. Dual link could go up to 2960x1850.
phil-news- said:|
| | \
|>
|> 1920x1200 (WUXGA) is a single link format. Single link can go all the way
|> up
|> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible)
|> format
|> would also be doable on single link. Dual link could go up to 2960x1850.
|
| Well, at least per the pixel clock limits on both single- and dual-link
| DVI, they sure could. The problem is, though, that the DVI standard
| never included a decent compliance certification test, nor is there any
| good spec on cabling, switches, and the like that would truly ensure
| that you can run full rates over any given comibination of such things.
| So as you approach the top-end clock spec, some will work, and
| some may not.
I called one of the makers of one of the switches I found like this (Blackbox)
and the guy I talked to tried to convince me that no one uses 1920x1200. My
response was "but they do use 1600x1200 when monitors of that type are rare
adn hard to find and are about to go out of production because the world is
shifting to widescreen so they have enough space to display 1920x1080 video?".
He didn't have an answer to that loaded question. I suggested he have the
product sent back to engineering.
| In article <[email protected]>, phil-news-
| (e-mail address removed) says...
|> |
|> | |> | \
|> |>
|> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way
|> |> up
|> |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible)
|> |> format
|> |> would also be doable on single link. Dual link could go up to 2960x1850.
|> |
|> | Well, at least per the pixel clock limits on both single- and dual-link
|> | DVI, they sure could. The problem is, though, that the DVI standard
|> | never included a decent compliance certification test, nor is there any
|> | good spec on cabling, switches, and the like that would truly ensure
|> | that you can run full rates over any given comibination of such things.
|> | So as you approach the top-end clock spec, some will work, and
|> | some may not.
|>
|> I called one of the makers of one of the switches I found like this (Blackbox)
|> and the guy I talked to tried to convince me that no one uses 1920x1200. My
|> response was "but they do use 1600x1200 when monitors of that type are rare
|> adn hard to find and are about to go out of production because the world is
|> shifting to widescreen so they have enough space to display 1920x1080 video?".
|> He didn't have an answer to that loaded question. I suggested he have the
|> product sent back to engineering.
|
| This monitor is 1920x1200. It is quite common for 24" LCD monitors.
So when will the KVM switch manufacturers understand that 1920x1200 is a common
desktop display resolution?
I found something in another model KVM switch that might indicate some possible
support issues. It seems many of these KVM switches have an on screen display
(the "OSD" feature). The switch will have to process the video, syncronize to
it, and insert their own video, to get that OSD to work. Their logic board
might not have the capability for some of the higher modes.
I don't need or care for OSD. I'd even prefer to not have it at all, for a
desktop environment.
| In article <[email protected]>, (e-mail address removed)
| says...
|> | In article <[email protected]>, (e-mail address removed)
|> | says...
|> |> What aspects of a DVI switch (KVM for example) would affect its ability to
|> |> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)?
|> |> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit
|> |> and can't do 1920 x 1200.
|> |
|> | What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get
|> | the refresh rate you're looking for at 1920x1200.
|>
|> 1920x1200 (WUXGA) is a single link format. Single link can go all the way up
|> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) format
|> would also be doable on single link. Dual link could go up to 2960x1850.
|
| At 60Hz, yes. By 85Hz single link is out of gas. That was my point
| ("what refresh rate?"). Do follow along.
I will push the refresh rate as low as I can make it work.
???
The lowest monitor
found will go down to 48 Hz (from HP). If I stick to the literal WUXGA format,
then it's 60 Hz. For the computers outputting the 1920x1200, the vertical rate
isn't much of an issue.
The analog computers will be outputting some lower
resolution to be scaled up, and at the lowest refresh rate I can get (because
that gives me some more resolution on those).
| In article <[email protected]>, (e-mail address removed)
| says...
|> | In article <[email protected]>, phil-news-
|> | (e-mail address removed) says...
|> |> |
|> |> | |> |> | \
|> |> |>
|> |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way
|> |> |> up
|> |> |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible)
|> |> |> format
|> |> |> would also be doable on single link. Dual link could go up to 2960x1850.
|> |> |
|> |> | Well, at least per the pixel clock limits on both single- and dual-link
|> |> | DVI, they sure could. The problem is, though, that the DVI standard
|> |> | never included a decent compliance certification test, nor is there any
|> |> | good spec on cabling, switches, and the like that would truly ensure
|> |> | that you can run full rates over any given comibination of such things.
|> |> | So as you approach the top-end clock spec, some will work, and
|> |> | some may not.
|> |>
|> |> I called one of the makers of one of the switches I found like this (Blackbox)
|> |> and the guy I talked to tried to convince me that no one uses 1920x1200. My
|> |> response was "but they do use 1600x1200 when monitors of that type are rare
|> |> adn hard to find and are about to go out of production because the world is
|> |> shifting to widescreen so they have enough space to display 1920x1080 video?".
|> |> He didn't have an answer to that loaded question. I suggested he have the
|> |> product sent back to engineering.
|> |
|> | This monitor is 1920x1200. It is quite common for 24" LCD monitors.
|>
|> So when will the KVM switch manufacturers understand that 1920x1200 is a common
|> desktop display resolution?
|
| I suspect it's an excuse to cover for insufficient product planning
| (they didn't see the price falling through the floor on these things
| - $270 last fall).
That well could be. Given the response I got from the rep at Blackbox, that
would be consistent.
|> I found something in another model KVM switch that might indicate some possible
|> support issues. It seems many of these KVM switches have an on screen display
|> (the "OSD" feature). The switch will have to process the video, syncronize to
|> it, and insert their own video, to get that OSD to work. Their logic board
|> might not have the capability for some of the higher modes.
|
| Certainly possible. I've had to insert some DVI logic into the
| design I'm working on. The information out there certainly isn't
| clear. It's possible they never tested on larger formats,
| neglecting them because they didn't see them coming so soon.
|
|> I don't need or care for OSD. I'd even prefer to not have it at all, for a
|> desktop environment.
|
| I don't want the switch to insert anything, for sure.
We sure agree on that. At least for a desktop situated KVM switch box, lights
on the box can do the job better at less cost. It's just a matter of passing
all the signals fully and not having mechanical contacts to do it.
I have found this _expensive_ KVM switch that looks like it might do the job
I need:
http://www.avocent.com/SwitchViewSC_DVI_4-port.aspx
The thing is designed for classified environments which require isolation
between the 4 (or more for larger models) computer connections. OTOH, maybe
that will end up with a better impedance matching of the signals, and better
RFI shielding, resulting in less double-edging on analog and fewer errors in
marginal conditions on digital (such as me hitting the transmit key on my 2m
HT too near the computer). Still, $500+ for a 4-port KVM? Ouch!