Video Distribution

[bebster]

Just an FYI, Zektor's bandwidth is 450mhz for video.

Jeff,

Since Cat5e cable is rated at 350 megahertz, can you explain how you get 450mhz for video distribution of 1080p?

[thecodeman]

Just an FYI' date=' Zektor's bandwidth is 450mhz for video.[/quote']

Jeff,

Since Cat5e cable is rated at 350 megahertz, can you explain how you get 450mhz for video distribution of 1080p?

I'm not sure where the 350 MHz rating for cat5e comes from, since wikipedia and the TIA/EIA doc state 100mhz ( http://www.nag.ru/goodies/tia/TIA-EIA-568-B.2.pdf ).

Cat6 goes up to 250 MHz, and Cat6a to 500 MHz. Cat7 to 600 MHz.

On to the speculation part:

He may be talking about the internal "pipes" that are switching the video signal inside the switch.

I'm finding from a number of different places that HDTV bandwith (720p as an example for broadcast) only requires 37MHZ.

http://reviews.cnet.com/4520-10166_7-5622773-1.html

However, there's further discussion about the proper formula for finding bandwidth across the chain of your devices.

http://archive2.avsforum.com/avs-vb/showthread.php?t=653094

Here's another calculation for the bandwidth requirements (in MB, not MHZ) of "uncompressed 1080p", suggesting it's 350mb

http://nslog.com/2006/11/18/1080p_math

However I don't know many who have sources of uncompressed 1080p in their home, and most of the media we watch is compressed with VC1, MPEG2, MPEG4, AVCHD, etc, requiring a fraction of the original bandwidth requirements but with little to no visible picture quality loss.

I hope that helps, it sounds clear as mud.

[Jeff at Zektor]

Bebster and Codeman, good comments and questions. Sorry for the late reply, just getting back from vacation. The Prowler CAT5 switch has both CAT5 outputs and local component video outputs. The higher bandwidth chips we use are more relevant when you are sending the video signal over RGB cable as CAT5 has the limitations described in the previous posts. However as an example, in our product the local component video output #1 will mirror CAT5 output #1 and so on. You can transmit the video signal over RGB cable up to 300' with a crystal clear result as long as you haven't shot a staple through the cable or used cheap product.

The 450mhz chips we use are probably a bit overkill but it does provide "headroom" in the mhz area. If a manufacturer uses a chip that tops out at 140mhz as an example, it will be taxed to provide as clean of a signal over a greater CAT5 cable distance compared to a higher bandwidth chip.

This is the Reader's Digest version from the sales guy at Zektor. If you want a deeper technical explanation I can have our CTO post with his perspective.

Thanks.

Jeff