HDMI: Extension, Distribution and Switching via Cat5e/6 - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 11 Old 10-04-2011, 09:17 AM - Thread Starter
Senior Member
 
Bob Hetherington's Avatar
 
Join Date: May 2008
Posts: 296
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 13
HDMI: Extension, Distribution and Switching via Cat5e/6
Author - Jeffrey Herman, Muxlab


Structured cabling plays a major role in audio-video systems today with Cat5e/6 being the most cost-efficient method to interconnect AV equipment in a multi-room or large venue environment. As more and more AV content is transmitted at HD resolution, there is a growing demand for the structured cabling system to support HD transmission over Cat5e/6 and therefore a greater need for HDMI over Cat5e/6 products. Furthermore the recent AACS Adopter Agreement pertaining to copy protection (Analog Sunset) and the gradual move away from unprotected component analog video is encouraging integrators to analyze future AV installations more closely in order to future proof them in support of HDMI. This article will focus on the key components needed to manage HDMI cabling over Cat5e/6.

Read the complete article at HomeToys.com
Bob Hetherington is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 10-04-2011, 11:36 AM
AVS Special Member
 
kenglish's Avatar
 
Join Date: Jan 2000
Location: Salt Lake City, UT, USA
Posts: 5,409
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 31
I just hope everyone will use shielded cable and proper ferrites and torroid cores on all their cabling, to reduce not only incoming interference, but also interference produced by their electronic devices.
Polluted spectrum is Useless spectrum.

Ken English, Sr. Engineer, KSL-TV.
"The postings on this site are my own and don't necessarily represent the Company positions, strategies or opinions."
kenglish is offline  
post #3 of 11 Old 10-04-2011, 12:14 PM
Member
 
skillz2882's Avatar
 
Join Date: Nov 2007
Posts: 39
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by kenglish View Post

I just hope everyone will use shielded cable...
Polluted spectrum is Useless spectrum.

I thought shielded cable was considered overkill for the standard residential environment (basement home theater)?
skillz2882 is offline  
post #4 of 11 Old 10-04-2011, 12:31 PM
Member
 
soulpunisher's Avatar
 
Join Date: Oct 2006
Posts: 138
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by skillz2882 View Post

I thought shielded cable was considered overkill for the standard residential environment (basement home theater)?

I have to agree with kenglish there is a lot of interference out there. Some of it is a simple fix there is a lot of power ran from big companies all the way down to homes that is not properly grounded and you get weird loop back interference among other weird problems I.R. leaks ect. We really need to redo a lot of power grids and ground homes better. This is just a small part of what he is talking about sadly. I am not an expert but I do know what he is talking about we had that problem at my work.
soulpunisher is offline  
post #5 of 11 Old 10-04-2011, 05:18 PM
AVS Special Member
 
Colm's Avatar
 
Join Date: Aug 2002
Posts: 4,652
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 89
Quote:
Originally Posted by kenglish View Post

I just hope everyone will use shielded cable and proper ferrites and torroid cores on all their cabling, to reduce not only incoming interference, but also interference produced by their electronic devices.

Ferrites will certainly help reduce RFI emissions. They might help improve the signal on the single-ended lines. But they won't do a thing to improve the signals on the TMDS pairs that carry video and audio. In fact they will actually degrade the signals on the TMDS lines slightly according to a research report on the subject I read. The eye pattern used to test HDMI cables closed in when ferrites were used.
Colm is offline  
post #6 of 11 Old 10-04-2011, 05:20 PM
AVS Special Member
 
Colm's Avatar
 
Join Date: Aug 2002
Posts: 4,652
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 89
Quote:
Originally Posted by skillz2882 View Post

I thought shielded cable was considered overkill for the standard residential environment (basement home theater)?

HDMI cable is shielded. The balanced pairs are shielded, and the whole cable is shielded. Cat 5/5e/6 is inferior for the purpose. You would have to use Cat 7/Class F cable to equal HDMI cable, and properly ground it. Shielded cable that is not properly grounded is no better than unshielded cable, and sometimes worse. Maybe you are thinking of cable for networking, not HDMI.
Colm is offline  
post #7 of 11 Old 10-05-2011, 05:48 AM
Senior Member
 
AVTrauma's Avatar
 
Join Date: Jan 2010
Location: Vancouver, Wa
Posts: 387
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Sure Cat 5e/6 is cheaper than HDMI, but if I had a run less than 100', I'd still go HDMI. Per the article "Through the wall - use the existing installed Cat 5e/6... really not that many homes have this, and (IMHO) if I'm making holes and putting in wire, it's just as easy to use HDMI. This seems more for commercial applications rather than home entertainment applications
AVTrauma is offline  
post #8 of 11 Old 10-05-2011, 11:48 AM
AVS Special Member
 
Kevin_Wadsworth's Avatar
 
Join Date: Dec 2002
Location: Columbus, OH
Posts: 1,194
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 14
Quote:
Originally Posted by AVTrauma View Post

Sure Cat 5e/6 is cheaper than HDMI, but if I had a run less than 100', I'd still go HDMI. Per the article "Through the wall - use the existing installed Cat 5e/6... really not that many homes have this, and (IMHO) if I'm making holes and putting in wire, it's just as easy to use HDMI. This seems more for commercial applications rather than home entertainment applications

I had existing Cat5e in my walls when I bought an HDMI plasma. SO I used an $80 active, dual-wire extender to get the HDMI signal to the set.

After dealing with the headaches and handshake issues for a year, I tore off the baseboard, ran an HDMI cable in a groove Icheselled in the wall, and replaced the baseboard. 2-3 hours of labor and $30 bucks for the cable. I wish I'd done that in the first place...
Kevin_Wadsworth is offline  
post #9 of 11 Old 10-05-2011, 12:09 PM
AVS Special Member
 
kenglish's Avatar
 
Join Date: Jan 2000
Location: Salt Lake City, UT, USA
Posts: 5,409
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 31
Quote:
Originally Posted by Colm View Post

Ferrites will certainly help reduce RFI emissions. They might help improve the signal on the single-ended lines. But they won't do a thing to improve the signals on the TMDS pairs that carry video and audio. In fact they will actually degrade the signals on the TMDS lines slightly according to a research report on the subject I read. The eye pattern used to test HDMI cables closed in when ferrites were used.

If the ferrites can degrade the signal that should be INSIDE the pairs, then the pairs must be capable of radiating noise and interference.

My biggest gripes, though, are the noise given off by plasma and LCD TV's and monitors, computer routers, and bad power lines.
HDMI cables are a big culprit, carrying the noise from the big TV's to other devices, as well as acting as a radiating "antenna" for such noise.

Ken English, Sr. Engineer, KSL-TV.
"The postings on this site are my own and don't necessarily represent the Company positions, strategies or opinions."
kenglish is offline  
post #10 of 11 Old 10-05-2011, 01:46 PM
AVS Special Member
 
Colm's Avatar
 
Join Date: Aug 2002
Posts: 4,652
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 89
Quote:
Originally Posted by kenglish View Post

My biggest gripes, though, are the noise given off by plasma and LCD TV's and monitors, computer routers, and bad power lines.
HDMI cables are a big culprit, carrying the noise from the big TV's to other devices, as well as acting as a radiating "antenna" for such noise.

Sounds like a problem with the originating equipment, not the cable. Ferrites on the cable are just a cheap fix that lets manufacturers avoid fixing the underlying problem.

Considering you are a broadcast engineer, I can understand your feelings about noise. For most of the rest of us, I think it is much less of an issue. With NTSC I used to be annoyed by the way impulse noise affected the picture on my TV when tuned to VHF low stations. Now that we have ATSC, the picture is rock solid as long as the signal to noise ratio is sufficient. I get all my local stations with no problems, and regularly get stations from 100 miles away in the evenings. The only problem I can attribute to noise now that affects me is with WiFi. Sometimes I lose the connection, apparently because of noise (neighbor's microwave?). Doesn't happen enough to be a big deal. But it would be an annoyance if I were using it to stream video. Have to go hardwire for that.
Colm is offline  
post #11 of 11 Old 10-05-2011, 01:59 PM
AVS Special Member
 
Colm's Avatar
 
Join Date: Aug 2002
Posts: 4,652
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 89
Quote:
Originally Posted by kenglish View Post

If the ferrites can degrade the signal that should be INSIDE the pairs, then the pairs must be capable of radiating noise and interference.

Theoretically, there should be no noise with the differential transmission system used for the TMDS lines. Ideally, the fields of the the wires will cancel out. Of course, we don't live in an ideal world. I think what is happening is that because of intra-pair skew and other problems, the differential signal is not completely in sync, and a small part of it essentially looks like common mode noise, and is therefore attenuated by the ferrites. And there are also single ended lines in the cable. FWIW in a HDMI cable, unlike a Cat 5/5e/6 cable, the individual TMDS pairs are shielded, and the whole cable is shielded. So, noise should be less of a problem with HDMI cables than with a media adapter using Cat 5/5e/6. Using shielded cable with media adapters is problematic because most of them are not designed to ground shielded cable.
Colm is offline  
Reply Community News & Polls

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off