AV Setup Help

[kevsnell]

Hi All,

Sorry if this has been answered before - have been through this section and read some posts but want some advice to make sure I'm going in the right direction.

My company has just started to run our own conferences throughout the UK and we have bought our own kit to use and this is all new to me and this is where I have an issue.

We tried running vga over cat5 with the following setup below but found that any distance over 20m caused the image to dull. This is a portal solution so we need to be able to have a setup that can handle a room lengths of max 50m length.

Current Setup:

Laptop on stage VGA output connected to a Kramer PT110 Transmitter which then goes over Cat5 to a Kramer PT120 reciever which then connects VGA into a Kramer VP‐719xl Switcher (have other feeds going into ie DVD player).

From Kramer Swicher VGA connection to Transmitter over CAT5 to Reciever then VGA connection into Projector.

This is where I need some help:
Is Kramer stuff not up to the job when it comes to the lengths we require?

I have seen Magenta, Extron and FSR mentioned - would these do the job?

Also is Cat5 the right way to be going as I have seen other things suggested?

How are you guys handling these kinds of length because I know it should be possible?

On a side note - we would like to add an option of capturing a flip chart and projecting it onto the screen.

Thanks in advanced - sorry if I sound dumb about this but it's all new to me.

Kev

 

[ruinexplorer]

I don't have experience with Kramer's goods, so I can't say if it's a problem there. First question that I have is what you mean by "dull" for the image quality. Could you try and describe what you are seeing? What is the image resolution that you are sending from the laptop? What is the native resolution of the projector and is your switcher also scaling the image? For 20m, I wouldn't say that it is necessary to use Cat-5/Balun for an analog signal, but if you are also doing the 50m, I can understand having the equipment. From what you are describing, I don't think that this is the first problem that you'd need to investigate.

 

[kevsnell]

Regarding what I mean by dull - is the image brightness becomes less with the length of cat 5 and a blur effect can be noticed on text nearly like a shadowing effect. As for resolution we are using 1024x800 which the projector is fully capable of - I believe the switcher to be fine as we have tested without the switcher in place and still get the same issue.

 

[jb595]

have you played around with the EQ and Level settings on the receiver?. normally you can fix the 'blurriness' with that. but 20m sound very short before issues.

 

[museav]

Regarding what I mean by dull - is the image brightness becomes less with the length of cat 5 and a blur effect can be noticed on text nearly like a shadowing effect.

How are you determining that the problem becomes worse with length? Are you saying that if you look at the output of the receiver at the end of the 20m run the image is okay but if you look at just the 50m run it is not with the 20m and 50m runs combined being even worse?

As jb595 noted, have you tried adjusting the EQ and level controls on the receivers, especially for the 50m run? 70m is is within the claimed distance but achieving that may require some EQ and level adjustments.

Are you powering both the transmitter and receiver on the longer run? You can power both devices from either one but only for runs under 50m, so your longer run would require either both the transmitter and receiver to be powered or separate, heavier gage power wiring between them in addition to the CAT cable.

What are you using for the CAT cable? The PT110/PT120 manual recommends skew free, STP cable for VGA applications. While it differs from the network world, video over UTP is one place where CAT5 is often actually better then CAT5e which can be better than CAT6 due to the potential skew introduced.

As for resolution we are using 1024x800 which the projector is fully capable of - I believe the switcher to be fine as we have tested without the switcher in place and still get the same issue.

What is the projector, are you sure it is capable of 1024x800? That seems an odd resolution and I just wanted to be sure that the projector supports it, many people do not realize that a projector handling higher resolution signals does not mean it will necessarily support every possible resolution below that.

 

[kevsnell]

How are you determining that the problem becomes worse with length? Are you saying that if you look at the output of the receiver at the end of the 20m run the image is okay but if you look at just the 50m run it is not with the 20m and 50m runs combined being even worse?

This was determined by doing the following:

Test projector direct into Laptop using VGA to set a base level.
Test cat5 over 5m, 20m and then 50m. And you can see a deterioration in the quality the longer the cable.

As jb595 noted, have you tried adjusting the EQ and level controls on the receivers, especially for the 50m run? 70m is is within the claimed distance but achieving that may require some EQ and level adjustments.

This is something I haven't tried so will try that later today to see what difference it makes.

Are you powering both the transmitter and receiver on the longer run? You can power both devices from either one but only for runs under 50m, so your longer run would require either both the transmitter and receiver to be powered or separate, heavier gage power wiring between them in addition to the CAT cable.

We have been powering each separately.

What are you using for the CAT cable? The PT110/PT120 manual recommends skew free, STP cable for VGA applications. While it differs from the network world, video over UTP is one place where CAT5 is often actually better then CAT5e which can be better than CAT6 due to the potential skew introduced.

We have been using Cat5e Network cable so after I have tested the Level and EQ option I may look at purchasing some different cables. Can anybody recommend a good brand of STP or Cat5 (or is this the same?)

Thanks for all the help.

 

[museav]

UTP (Unshielded Twisted Pair) and STP (Shielded Twisted Pair) are the more generic names for cables where the two conductors in a balanced pair are twisted together to minimize crosstalk and EMI, the twisting causes any noise induced noise to be induced more equally in both conductors and thus be more effectively canceled by a differential input.

CAT'X' (3, 5, 5e, 6, etc.) refers to twisted pair cable that meets specific standards for Ethernet or network use.

So, CAT5/5e/6 are all forms of UTP or STP cable while mic cable is an example of STP cable that is not a CAT cable. Confusing enough?

The reason that UTP and STP are often used in reference to audio and video transmission is that these are not Ethernet or data communications and thus the CAT designations are not really directly applicable. In fact some of the low skew or 'skew free' cables made specifically for such use may not meet all of the standards for any CAT designation.