Cat 5 & 6: Why Do We Need Two for HDMI?

Jeff,

Can you comment on the vendors who are producing single wire Cat5/6 HDMI baluns?  What are the pro’s/con’s vs. 2 wire?

Also, you mention to be careful when wiring the 568 A/B standard, what do you suggest as an alternative?

Thanks in advance!

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I am currently testing a single Cat6 HDMI solution that claims 1.3 spec with Deep color to 100ft+. I’ve only gotten to put a 1080i signal with 100ft cat6 so far, with a 25ft HDMI on one side, and a 4ft on the other. The results have been promising so far, although having always used the same thought process you explained above with needing two cat cables I was a bit skeptical, which is why I bought it just to test it out.

Also, much like Ken I am curious are you recommending a straight through pin out instead of the standard 568a standard I typically use? I believe io read before where you did actually say that, and I can see the benfits, although if properly executed, the pairing would only be crossed just at the very end, and only once with how small an amount of untwisted cable exists in my terminations.

I’d love to hear your specific thoughts on this since I am just starting to test baluns for the first time.

I look forward to the response.

I am wondering the same thing, there are many single Cat5e and Cat6 HDMI baluns that only use one cable and they recommend using the EIA/TIA-568B standard to wire by. For a specific example see Snap AV’s HD-1CAT-1080P-130.  I always assumed they converted the HDMI signal to a data stream and it depended on the “Bandwidth” and ability to reduce alien cross talk of the shielded or unshielded Cat5e or Cat6 cables you used. You learn something new everyday, but that’s why we come here.

I am curious though the best way to terminate the cables if it helps make a better/ steadier connection.

Thanks in advance for the response.

I am currently writing an article on the single and double Cat5/6 technology. It will cover this subject pretty deep.

However, here is the short of it.

As for the 568 issue:
As many of you know, the 568 pin out is not uniformed. In 568a the orange pairs are split and in 568b the green pairs are slit. Under Lan conditions this is really OK. The problem is when you match that to the chip set pin outs inside each Cat 5 HDMI receiver. The linearity of the RJ45 pin out (that is 1 through 8, in that order) should mirror the HDMI pin outs for the High Bandwidth TMDS video channels. That does not match that of 568a or b pin out standard. What you get is three of the four TMDS lines shared on opposite pairs. This is disastrous for the ever so critical balanced line HDMI video channels. The only way to correct for this is to modify the artwork on the printed circuit board before connecting to the RJ45 connector. This of course causes more trouble with board integrity.
There is so much more to all this, it would require lots of room and many illustrations. As I said, I am working on that right now. I will also be at EH Expo next week for those of you that may want to dig into this also. My schedule is posted on the CEpro web site. Please feel free to see me if you would like to discuss this or any other issues.

Also, CEpro has my email address incorrect. It is really .(JavaScript must be enabled to view this email address).
And here is the link to the schedule.

http://www.cepro.com/article/dpl_labs_boccaccio_to_field_hdmi_questions_at_ehx_spring_2009

Shouldn’t this be a data rate issue?
I thought they were using the Cat5 like ethernet,
not just wire. 
Assuming that HDMI is 1.5 Gbps (or is that GBps?)
the first Cat5 systems required 2 connections to reach the data rate required (1gb ea) the newer ones probably just use full duplex to reach 2gb ea

Anyone talked to Gefen or one of the others?

I have not had a chance to test single cable baluns for HDMI. But I beleive using standard Cat5e or Cat6 (data rated) could create video quality issues.I suggest looking into a Low-Skew UTP cable designed for video and audio,not data.Look for NanoSkew or VideoTwist types,ideal for KVM and blade-edge computer applicatons.This type of cable works best at longer runs.

I have gefen hdmi cat5 extenders they recommend 568B termination. I have an issue with rf interference from screen motor or amps turning on causes a mometary loss in picture.

I have the Video on a cat 5e 12metres long should I re-terminate with straight thru wiring or would this not function?

I have the DCC signal cat5 wired the same and going via a patch single patch connector ie two cables.

Thanks

We are currently working on a solution for this. It is a common problem throughout the world. I just returned from the UK and found this problem being common there also.

Be aware that these issues cannot be solved nor replicated under the same rules we used with typical interference issues.

Will Keep you posted.

HDMI Baluns comes in many forms. Some uses either a Cat-5e or Cat-6 etc…And some baluns only allow you to run a certain length of 30m, 90ft. etc…But from our experience:
1) If your HDMI balun does not perform as you would like make sure you buy the Cat cable from a company who really supplies quality Cat cables. Many installers/integrators buy the Cat cables with too much copper alloy thus when you hook up the baluns the signals are weak and it gives you problems.
2) If you have good quality Cat cables and it gives you problem, try using a higher quality and thicker gauge HDMI cable on both the Transmitter and Receiver end. The quality of the HDMI cable should help tremendously…try not to get the 30awg 1.99 on eBay either.
3)If you still have problems with the Cat cable you are using try using a Cat-6 shielded cable and that’s what our company recommends our clients to use, it will allow the HDMI baluns to work better with the ability to go up to 175ft. with a 1080p resolution. Even though you don’t need such a long distance HDMI balun but the chipset has room to expand without the limitations of a 90ft. and using the near max or max limitations of the balun.
4) If you are still having problems try using a different HDMI balun from a different company. HDMI baluns comes assembled from China using different chipsets some will work with Cat-5e & 6 and some will work the best with Cat-6 & Cat-6a/7. Some will give you 90ft. 1080p max and some 150ft. 1080p max and some 180ft. 1080p max, the baluns may look the same but the chipsets used are not…you get the picture.  Hope this helps.

I do agree that the best dynamic range over the entire link should be maximized. One should not assume that just because a system may work with distances to 175 Feet should suggest that this is the rule. This is where you must be careful guessing what may be good and what may not. We have had countless Cat 5 and 6 products in along with Cat 5 extender systems from all walks of life. So far there has not been one that has shown a significant amount of mask margin percentage ( out of the single digits )to qualify any as being a sure guarantee with Cat 5 over 100 feet at 1080P 8 bits ( 145 MHz). When your working on the edge of integrity any ancillary hiccup throughout the system can sting you.
That still does not take into account issues with timing, startup voltage, and EDID/HDCP serial data of which can be equal to or more problematic than just the video itself. Most extenders don’t even provide correction for these channels, only for video. At the end of the day you get what you pay for.
  Some silicon can be designed and used as adaptive ( automatic ) electronics while others are not. Although you may see some with gain specs from as low as 2db to a high of 27db, they are not analog. They are pre-emphasis or de-emphasis systems and do not operate the same way as we would have pictured them in analog. The science behind Cat 5 extenders can be pretty deep and no doubt will get deeper as more improved products hit the market. This is not even mentioning the ramifications used under Rev 1.4. There are newer protocols used in 1.4 that may change the overall operation of Cat 5 extenders.
Oh, and one more thing. Lets talk the right language here. The term Balun describes a device for converting a balanced line into an unbalanced line and vice versa. Non of that is done with Cat 5 Extenders. I would love to know who the clown is that gave it this ridiculous name!
GET ON THE STICK PEOPLE, IF YOU USE THE WRONG VOCABULARY YOUR QUESTIONS CANNOT BE UNDERSTOOD!
You can always get these answers from DPL labs. We are now launching an improved effort to get the word out by way of the web site with articles, white papers and links. Or contact a DPL member that gets all this first hand. Check it out. It is being updated daily. dplrating.org.