AV active signal distribution

Discussions around the satellite system and video distribution.
quintonrhq
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AV active signal distribution

Postby quintonrhq » Thu Feb 18, 2010 9:16 pm

Our stake presidency approved a plan to upgrade the video signal distribution within the stake center and a second building with a satellite receiver. The closed circuit RF cable distribution system was left in place and a parallel video system was installed. It resides in the same rack space housing the satellite receivers and RF modulators.
The heart of the system is a 4-port YPbPr component video amplifier with a stereo audio transmitter with 4 x RJ-45 outputs. At the receiving end of each cable segment is a small box with an RJ-45 input which recovers the 3 video channels and stereo signals. Cabling consists of CAT-6 wire. Since the CAT-6 wire is not used as an Ethernet path, run lengths in excess of 300 feet are practical. CAT-5 wire was tested to 700 feet with minimal loss. Wall plates use RJ-45 yellow connectors. These are flush to the wall and present a low profile to avoid damage. Multiple connectors may also be present in the same wall plates such as Ethernet, F-connectors, and telephone jacks.
Each video channel is independent so that combinations of inputs can be used. At present, one channel is used for composite video and the remaining two channels carry S-video. Component video has been used as well.
The stake center has two video amplifiers which support 8 video drops. Using a patch panel, up to 4 audio programs can be routed.
A single component output video amplifier drives a single input amplifier over a CAT-6 segment to bring a video camera signal into the video closet. This can then be patched into the general system for stake conference broadcast to remote rooms and obstructed viewing locations. In concept, the video camera signal could be routed through any of the video runs by moving an RJ-45 jumper cable.
At the projection locations, a short cable connects the projector to the receiving amplifier. There is a store of RCA to S-video or RCA to RCA jumpers. If required a 3.5mm audio plug to RCA connector is used to patch into a TV or the building sound system in the Relief Society or Primary room via the ‘crab’ box. This works quite well for secondary audio programs where only one channel is connected. There is no need to position a VCR at each location.
The stakes inventory of projectors all support S-video but as these units are retired they are being replaced with projectors having component video inputs such as the Hitachi CP-X450. The operational standard at the stake center features a camera, satellite IRD, DVD recorder, and projectors all using S-video.
When a second language transmission over wireless headsets is requested, the FM transmitter is located to a central projection point and the secondary audio is connected to the FM transmitter.
The 4-port amplifiers cost $160 each and the receivers were $80 each.
LAN wiring runs to each video central location to support webcasting.

michaelbuhrley
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Location: Mission Viejo, CA

AV distribution

Postby michaelbuhrley » Sun Mar 07, 2010 7:44 am

That sounds like an ambitious project. Could you provide some additional information, i.e. specific part numbers, manufacturers, overall project cost and how well it is working for you?

I am also interested in your approach to 2nd language broadcasting as that is something that we regularly deal with both with broadcast feeds and live meetings, and in the case of the stake conferences that originate from SLC we have to switch from live to satellite feed quickly.

We have talked about the need to upgrade our buildings but have not known where to start.

Thanks!

quintonrhq
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Location: Bellevue Washington USA

AV distribution amplifier

Postby quintonrhq » Tue Mar 09, 2010 10:38 pm

Thank you for your interest. The web site www.avextender.com advertises two models that were used: AV-702Z-114Y at $160 and AV-701Z-121 at $80 per copy. These were ordered directly from Taiwan. First a pair were ordered via credit card for a proof of concept test. Then 3 and 10 units were purchased respectively. Four boxes of CAT-6 wire at $110 per box were needed. The wire pulling was done with volunteer help. The jumper cables, face plates, connectors, etc. were largely purchased from www.bestlinknetware.com. Each outlet costs about $10.
The stake center had a 32 position patch panel installed for about $200 for all of the video and audio cables and patch panel connectors. An additional 24 position RJ-45 patch panel manages all of the CAT-6 cabling. Making the right connections makes it look fairly busy but it has proven to be much easier to do than to open the rack box up and move cables around. The second building did not need any patch panel.
The system has been used for several conference broadcasts (3 languages) and a stake conference with two active languages and video camera. Every outlet was active. Unsolicited reports have come to me that the video quality was perceived to be much better.
The drawing notes are attached, if a bit hard to read.
Attachments
MFP Type 103_20100309213353.pdf
(81.42 KiB) Downloaded 160 times

shanebankhead
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Location: Mesa, AZ, USA

Postby shanebankhead » Fri Apr 09, 2010 3:43 pm

These kind of video baluns are cool and have some advantages over standard methods. I've looked into this sort of thing as well, but it was never quite the right solution for my application, so I haven't had any first hand experience with them.

I'm curious about why you needed to go this route. What does the balun accomplish in your installation that an RF modulator or baseband video distribution system couldn't do? It seems like the baluns usually are advantageous if you are dealing with extremely long cable runs, or want to distribute higher quality video sources (s-video, component, VGA, etc.). In the church installations I've seen, expeciallly the ones I work with, it seems like composite video over modulated or baseband lines does just fine for typical use, and produces as good of a signal quality as anyone would expect. In my case, I would love to distribute S-video or component, but our existing modulated video looks great, so I don't think I could justify needing the upgrade.

Please don't read this wrong- I'm not questioning or criticizing. I'm genuinely interested in your decision process, since I'm currently involved in the design of the A/V system for a brand new Stake Center, and I'm curious to know what others are doing. With the kind of multimedia presentations and multi-building broadcasts that our stake does regularly, the "standard issue" system really is not going to cut it, so I'm working on getting approvals for some upgrades. Right now, we're planning on composite video and RF distribution, possibly with some baluns for VGA distribution.

I see that I'm a little late to this thread, but I'm curious if anyone else has more feedback on this.

shanebankhead
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Postby shanebankhead » Fri Apr 09, 2010 4:10 pm

Also, to comment on the language question that Michael posted: We only do English & Spanish in our buildings, so it's a pretty easy standard setup. The two languages are distributed on left & right audio channels, and modulated onto two TV channels, one for each language.

I installed a balanced audio run from the DA in the library rack to the chapel so the headset transmitter can be connected either in the chapel or in the library. For any broadcast we have either option of using headsets, or putting Spanish on a TV in the RS or Primary room.

The only other interesting thing we do is I have it wired so we can feed a local Spanish translation into the distribution system so we have the same setup when doing a local meeting or broadcast. This also requires the use of a pager (voice-over) module which adds some of the "English" audio when there is no translation (during songs, for instance), but attenuates the English audio while the translator is speaking. Anyway, this all works quite well for us, but it seems everyone has a different need and approach.

quintonrhq
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Location: Bellevue Washington USA

Thought process behind the design

Postby quintonrhq » Mon Apr 12, 2010 11:15 pm

The video distribution amplifiers are active amplifiers, not just simple baluns.

At the risk of sounding pedantic, the reader is asked to closely read that composite video is not the same as component video. Think of composite video as 1 channel video, S-video as 2 channel and component video as 3 channels. I apologize for all of the abbreviations that follow.

The RF distribution systems were just not producing a picture that compared with the signal I could see on my own DVB satellite system from Salt Lake. Both RF systems were adjusted, terminations checked, etc. and it was just not thrilling. The ATSC digital broadcast transition was under way and the familiar NTSC standard was becoming dated. Most of the projection locations were being viewed with LCD projectors that had no NTSC tuners so that a VCR, acting as a tuner, had to be set up with each location. While us tech guys could usually dredge up an old VCR, it was all too often a source of confusion to the staff to get the set up right the first time. The IRD's supplied have much better video output quality than was being realized by the RF distribution system. How to improve the pipe?

Conversion of the satellite signal into an ATSC channel? An ATSC modulator is very costly and the industry has no motivation to make them inexpensively. The conversion problem at the LCD projector still remains. RF distribution is a dead end.

Baseband video distribution (composite video) A single conductor cable but no better than the RF signal plus no audio is present. Not an improvement for a large building.

What connections will modern video equipment have in the next few years? Many LCD projectors have composite, S-video, component video, and HDMI connections.
HDMI is a real favorite to cover the fullest technology span, however the standard has some tricky digital rights issues for moving in and out of that domain. Wiring run lengths are a problem. Fiber or dual CAT wiring is needed to transport the entire standard. Fiber is just too costly and exposed connectors would be broken. Love it, but not my choice for church needs.
Component video can give HD performance and can be placed on a single CAT wire. It's pretty simple, 3 analog video signals. This became the target system.

Passive video baluns can be used to move video around but the run lengths are at or beyond what our stake center demanded. An active video distribution scheme was wanted.
The compromise was found using the above referenced boxes. (There are other vendors.) What is brought to each outlet location are 3 video signals and 2 audio channels on one cable. Each video channel is independant of the other so that 3 composite signals or a composite and S-video signal or a component signal can be sent. So while the stake is using the middle configuration, it can just as easily be reconfigured up or down. Set up is straight forward.
Since the CAT-6 wire is just an RJ-45 connector on each end, it can be used any which way.
The remote audio signals have worked nicely to drive the alternate headset transmitter and in room audio connections.

shanebankhead
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Postby shanebankhead » Wed Apr 21, 2010 10:31 am

I follow you completely, and am intimately familiar with all of the technical details you are discussing. My questions were not out of ignorance, just curiosity.

In my circles, we generally refer to a balun as any device that converts an unbalanced signal to a balanced signal for transmission over twisted pair, whether active or passive. I suppose that is not tecnically accurate, since baluns are traditionally passive. But right or wrong it's the term I've become accustomed to hearing and using over the years. Sorry for the miscommunication there.

In any case, I certainly wasn't arguing that component distribution wouldn't produce superior results. I'm just debating the issue for my own installation whether the benefit of upgrading the signal distribution system would be practical in our case right now. This is the context of my interest in your installation.

As I mentioned, our existing RF and baseband distribution seems to work just fine given the simple program material and our display options. I'm disappointed, but quite certain that most people in our congregation would not notice or appreciate a change to component distribution over our current methods. Instead, my biggest motivation to upgrade the distribution system has more to do with future-proofing the installation. It is extremely frustrating to me that brand new building installations are still centered around analog NTSC modulators and rely on the availability of old VCRs to serve as demods for a projector. Most television sets on the market today still include an NTSC tuner, but for how long? It seems like all of the existing church installations will hit a brick wall at some point when existing obsolete equipment starts needing replacement. There are already some types of analog NTSC equipment that have virtually disappeared from the market.

Also, as you were also discussing, I don't believe the industry is taking a clear direction for how to upgrade or replace older CC installations in favor of newer technology. Granted, there are some good alternatives (your method probably being one of the best) but I still feel that all of the available options involve some disadvantages and compromise, and that there is not an obvious easy solution right now.

My dilemma in our local installation is whether to take the plunge and invest in a new system now, or hold off a little longer to see where the industry goes. Of course, this all really depends more on how much of this proposal I can sell to the stake right now, but that is another battle entirely.

Anyway, I'm sorry if my inquiry sounded overly simplistic. But again, I was just curious to get more information on your decision and design process, since I may be taking a similar route in the near future. Thanks for the info.

quintonrhq
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Location: Bellevue Washington USA

Postby quintonrhq » Sat Apr 24, 2010 12:23 am

Some of my responses have been targeted to the passive readers of this thread. There were certain concepts that were missed in explaining the methodology to administrative individuals. A photo set was provided of the same scene with different transmission schemes.

The tipping point of this transmission evolution may come from the interbuilding communications issue and non-satellite useage. If the pipe needs to become two-way or at least wider for computer projections, then the old RF CC system will need an auxillary path. Folding back onto the RF system may finally become too trying.

May my VCR RIP.

gpsin
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Postby gpsin » Wed Dec 22, 2010 2:08 am

[font="]Hey, I am really astonished as well as impressed with this project. It has been designed with many goals in mind. It is very intricate in dealing with the specifications and target of the project. I really hope that this idea is spread over so that other organizations also can benefit.[/font][font="]

[/font]
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