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Inside HDBaseT Technology: A Better HDMI Extender

HDBaseT delivers 4K x 2K video, audio, control, Ethernet and up to 100 watts of power over a single Cat 5 cable up to 100 meters ... without degrading the signal. How'd they do that?


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HDBaseT: One Cat 5 cable for 100 meters of uncompressed video, audio, control, Ethernet, power, HDMI pass-through

If it is implemented on a large scale, HDBaseT could be an exciting development in whole-house multimedia distribution -- enabling video resolutions (4k x 2K), distances (100+ meters) and extra features (100 watts of power) that we've never seen over a single Cat 5 cable.

The technology originally was developed by Valens Semiconductor and marketed under the 5Play brand. Now the official HDBaseT 1.0 spec has been ratified by the six-month-old HDBaseT Alliance formed by Valens, LG Electronics, Samsung Electronics and Sony Pictures Entertainment.

Contrary to overzealous reports, HDBaseT is not a replacement for HDMI -- and will not be a replacement anytime soon.

In fact, the technology is simply an enhancement to HDMI. It still requires an HDMI chipset at both the transmitting (source) and receiving (display) ends – just like any other HDMI-over-Cat 5 solution.

In any case, “We’re not trying to be an HDMI extender,” says Micha Risling, VP of sales and marketing for Valens Semiconductor and spokesperson for the HDBaseT Alliance. “It’s only one segment that we’re after simply because we can. But we’re trying to introduce much, much more than that.”

In the HDBaseT universe, video, audio and related data signals are processed by the HDMI chip as usual, and HDBaseT takes it from there.

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FIGURE A: The Valens VS100 System Functional Diagram

Building a Better HDMI Extender


Most of today’s better HDMI extenders utilize two runs of Cat 5 or Cat 6 twisted-pair cables.

Typically, one cable is reserved for TMDS, transmitting video, audio and associated timing clock signals. The other carries the handshaking signals (with customized electronics for maintaining signal integrity) and low-current power for driving the HDMI electronics at the receiver.

HDBaseT: The Whole Picture
I. HDBaseT Cat 5 Technology is Useful, but No 'HDMI Killer'
II. Inside HDBaseT Technology: A Better HDMI Extender
III. Is HDBaseT a Game Changer? (coming soon)
More vendors now are going the one-wire route, using proprietary schemes to push the audio, video, control and power over the cable without compromising performance … much.

In both cases, the cables are susceptible to the same electromagnetic interference that plagues any transmission of high-frequency signals over long wire runs.

To mitigate EMI, HDBaseT transmits lower-frequency modulated signals across the cable using Pulse Amplitude Modulation (PAM) – the same technology used for coding Ethernet signals onto twisted pair cabling.

With this method, digital data is represented as a coding scheme using different levels of DC voltage at fairly high rates (in the order of 125 mega pulses per second or more for Ethernet). While 100BaseT Ethernet uses 5 Level PAM (PAM-5), HDBaseT uses a proprietary version that is slightly different. Some of the newer high-speed Ethernet coding schemes, like 802.an (10GBaseT), use 16 Level PAM.

In the case of HDBaseT, PAM is used to “modulate” all of the HDMI and control signals onto each set of twisted pair wires. The magic is in the proprietary coding scheme used to get all of that data onto the wire bundle, allowing content to be sent across a single Cat cable without being degraded by the electrical characteristics of the wire.

It is important thing to note that, while HDBaseT uses the same coding technology as Ethernet and does have an Ethernet channel, it is not Ethernet based. It does not use Internet Protocols (IP) either. It just happens to use the same type of twisted pair cable that most associate with Ethernet.

Translating HDMI to HDBaseT


To really understand what HDBaseT is all about, it is useful to take a look at the chipsets themselves.

Valens currently is the only provider of HDBaseT chips – the VS100TX transmitter and the VS100RX receiver.

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FIGURE B: Valens VS100TX Transmitter High-Level Block Diagram

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FIGURE C: Valens VS100RX Receiver High-Level Block Diagram

The pins of interest initially are the TMDS lines that interconnect directly with the TMDS lines on the associated HDMI transmitter or receiver chip.

Although we’ll refer to the designators from the transmitter (VS100TX in Fig. B) for this example, the concepts are the same for the receiver as well.





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Article Topics

News · Product News · Video · Multiroom Video · Wire and Cable · HDMI · Hdbaset · Hdmi Extender · All topics

About the Author

DrFlick, Play
I provide consulting and implementation services for manufacturers and consumer electronics installation companies on new technologies, products, and strategies related to standards-based Distributed Audio, Video, Communications, and Control (DAVCC) systems for the home and consumer market spaces. My long-term goal is to be instrumental in the development and deployment of entertainment systems on space stations and space colonies.

10 Comments (displayed in order by date/time)

Posted by CaW  on  07/19  at  02:47 PM

They might not want you to think its a replacement, but its a replacement.  As a tech savvy consumers and a DIY, I sure as heck like the idea of being able to create my own video distribution with standard user terminated Cat6 cables instead of relying on some kludgy after market add-on.  Building it on HDMI/making it backwards compatible, etc, just reduces the chance of litigation against the companies behind it.

Posted by deathtohdmi  on  07/19  at  04:48 PM

Death to HDMI wink I wonder what the poor “audiophile” companies are going to think of this when we finally swith over.

Posted by DrFlick  on  07/19  at  06:07 PM

CaW,

Yes, from a cabling perspective, this seems like a great solution for point-to-point runs.  However, I still caution you when you start adding multiple sink devices without some good EDID and CEC management tools (and an infrastructure to support them).

  =D-

Posted by jbrown  on  07/20  at  09:34 AM

I think everyone universally hates HDMI, and with good reason. It has suffered from three main issues from the beginning. 1. ridiculous distance limitations unless you spend a fortune. 2. insane copy protection lockdowns for no good reason. 3. possibly the 2nd worst A/V connector design ever (s-video is still the worst). Hopefully this addresses at least two of them.

Jason Brown
http://www.asktheadvisors.com

Posted by Clint DeBoer  on  07/20  at  10:13 AM

No offense to Julie & Derek, but the article is a bit misleading. You are drawing from the existing chipset to make a statement that “Contrary to overzealous reports, HDBaseT is not a replacement for HDMI—and will not be a replacement anytime soon.” (which you then contradict with the statement from Micha Risling, VP of sales and marketing for Valens Semiconductor.) Let me be clear, HDBaseT is certainly NOT an enhancement… not in the long view.

Had you spoken to the president of HDBaseT (as I have) you would have found that this is INDEED designed to be an eventual replacement/competitor to HDMI. What you have observed is simply that: 1) the EXISTING chip technology is designed, necessarily, to interface with HDMI, since it was designed as an HDMI balun; and 2) of COURSE it’s not going to replace HDMI right away as it will need to be rolled out as a concurrent technology until the AV equipment supporting it hits critical mass and HDMI can be phased out…

HDMI is a connection and spec, nothing more. There is no magic, and certainly no reason that it has to stay around in order for HDBaseT to function. This is only based on an existing chipset that has been on the market since WELL before the specification for HDBaseT was finalized.

So the real question is how quickly can it be rolled out? My guess is VERY quickly based on the desire for AV receiver manufacturers to be the “hub” of the home theater. HDMI didn’t allow for this, but HDBaseT does.

Posted by DrFlick  on  07/20  at  11:09 AM

Clint,

No offense to you, but your article at http://www.audioholics.com/news/industry-news/hdmi-dead-hdbaset is about as misleading as it gets.  In fact, that specific article is one of the primary reasons I wanted to write something that factually describes the technology behind HDBaseT, not just publish some overzealous headline making statements that obviously are just designed to attract hits on a web site.  If you had said that we finally have a potential solution that could replace the dreaded HDMI connectors and cables, then I could agree with the concept of what you were trying to say.  However and maybe it is just me, releasing a technology that claims to be killing off the exact technology it REQUIRES to run makes no sense.  You allude to their potentially licensing the HDMI and HDCP technologies to include into a single chip of their own sometime in the future, but all that does is reduce the form factor and cost.  It still keeps HDMI very much alive – it just changes the connection media and connector.  Additionally, with their chipset still directly supporting pass-through to an HDMI connector the entire CE industry has pretty much decided to embrace, my view is that the only thing they are delivering is a standardized alternative for connecting HDMI devices together – an HDMI Extender with some additional optional (and in some cases potentially incompatible) features.  Further, you neglected to mention the additional cost of including their technology into devices already being gouged by low profits and prices when it actually is less expensive to continue using the current HDMI connector for non-long distance connections.  Add on top of that your blatant acceptance of how the power distribution possibly could be delivered and all you have done is confuse the readers even more.

I believe it would have been more beneficial if you actually had done some research into how the technology works, presented the pros, presented the cons, presented things to look out for when selecting it as an alternate connectivity solution, and then made a case for why it might become an interconnection standard if and when others in the industry can justify embracing it.  I also am curious why you missed out on stating some of the positive features like “rolling back” to Ethernet that eliminates some of the interoperability confusion in the market – I guess that part was not in their marketing brochure.  You also missed highlighting an ugly feature like forced distance limitations as a form of DRM enforcement – I guess that was not in their marketing brochure either.  All you printed was the hype given to you by the company.  If we relied on that for all of our purchasing decisions, we would own one of everything.  We have yet to see how it pans out in real life installations and with real products.  Either way, it will be a good alternative to the current HDMI connectors, but it definitely is not an HDMI killer.

I will stand by what I wrote over pushing the Fear, Uncertainty, and Doubt that you are so willing to propagate.  My goal is to provide clarity, not regurgitate marketing confusion.

  =D-

Posted by Julie Jacobson  on  07/20  at  12:18 PM

sorry, Clint, didn’t meant to pick on you ... your article was great and you guys do an awesome job. AND ..... We use sensationalist headlines all the time.

In fact, we did interview Ariel as well. Naturally, they would LOVE to replace HDMI with their technology ... so did 1394 and so did every other technology.  But it won’t even be a consideration for a hugely long time.

Posted by DrFlick  on  07/29  at  02:48 PM

If anyone is interested in a more technically-detailed analysis of HDBaseT, I have posted a more in-depth version of this article at my blog site http://thedigitallifestyle.com/cs/TDL/b/custom/archive/2010/07/25/Clearing-up-the-HDBaseT-Technical-FUD-_2D00_-Installment-031.aspx.

  =D-

Posted by DrFlick  on  08/07  at  10:22 AM

Clint,

I appreciate your public apology at about 32 minutes into your recent podcast at http://www.avrant.com/?p=1460.  As mentioned, if we believ all of the sensationalism, hype, and FUD from vendors’ marketing departments without taking the time to understand how all of these new technologies actually work “on the wire,” we would own one of everything – and be disappointed in 90% of them once we have them.

  =D-

Posted by UKHDMi  on  09/25  at  08:51 AM

Just launched HDbaseT Solution http://www.youtube.com/watch?v=DkT0AOBeVAc

Any feedback?

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