High Res Quad Color Processors?

[kdberg 0]

I'm installing a 16 camera DVR based system for a customer, but they also need four of the signals combined into a high quality quad display that will then be driven to three stations a few hundred feet away. The cameras are high res color (470 lines) , and I want to preserve as much of the resolution as possible. Was figuring on using 800 line capable monitors.

 

Looking for recommendations on specific quad processors that will provide good real time 800 line images.

 

Ken

[Cooperman 0]

kdberg

 

I don't claim to be up to date on all the latest 'quads' on the market, but I certainly can't think of any that have a frame store capable of supporting that resolution (at least not in the CCTV industry).

 

Unless anyone knows of a suitable unit, it's possible that you may find something in the Broadcast sector, but that's going to be big bucks.

 

I'm not really sure why you need to go so far up spec on a unit if you're using 470 line cameras. Any top end 'quad' is going to produce a very acceptable image for most applications.

 

Just a couple of other thoughts; If you're splitting the signal off to three points each a few hundred feet away, you may want to use a good quality Video Distribution Amp. to maintain the signal levels.

 

If the first is a few hundred feet, and the other two are in close proximity, you could simply use a higher grade cable, and looping outputs, without the VDA.

 

Also, depending on the size of the displays, if it's anything less than 17", I would be tempted to go for a flat panel LCD, rather than a conventional CRT model.

 

The 800 lines centre resolution will drop off (towards the edges) on a CRT, and if the display is a permanent quad, the tube will burn in very quickly. With an LCD neither of these problems apply.

 

If you'd already thought of this, apologies for stating the obvious.

[kdberg 0]

All of the cabling is home run to a relay rack, so was already planning on a distribution amplifier.

 

Although the cameras are only 470 tvl, two side by side images would be 940 tvl if there was no information loss. Hence my thought for an 800 tvl image. If I am thinking about this wrong, let me know.

[Cooperman 0]

I like the thinking behind your logic, but unfortunately it doesn't quite work like that.

 

As an example, if you imagine a full screen camera image which clearly shows the '470 line' resolution bars on a test chart, if you then squash (compress) that image down to 1/4 of its original size, you can no longer resolve those same bars.

 

As I recall, with a quad unit, the output resolution of a full screen image (comprising 4 quad pictures) will overall be the maximum resolution supported by the digital memory / frame store.

 

So whether you use 600 line B&W cameras or 330 line colour models, the limiting factor on output resolution, is never likely to be much better than perhaps 500+ lines over the entire image.

 

It does make some difference if you use top quality cameras; the individual quadrants undoubtedly look better, but you will always be limited by the quality of the compression / storage circuitry.

 

Perhaps another way of looking at it is, if you have a VGA picture divided into four on a computer monitor, each quadrants resolution will be 1/4 VGA.

 

I think I'm waffling now ... time to shut up

[AVCONSULTING 0]

You are correct in saying that your resolution is cut down to 1/4 res when viewed in quad compression. Still it should afford a good enough picture to see what is going on. Plus there are several quads that will post real time viewing in the quad mode.

[rory 0]

Are you recording it? If not why does it have to be the ultimate res?

There are systems for this, using rear projection but they are not cheap.

 

another option is 3x 4 channel high quality muxes, as they will give you the best image.