Video distribution amplifier?

Conversations around originating a webcast for conference, including cameras and mixers.
aclawson
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Video distribution amplifier?

Postby aclawson » Wed Feb 15, 2012 10:58 pm

There exists a chapel with a video point of input in the wall of the overflow. This port accepts cables with a composite (RCA) termination.

The other end of this run is just under 170' from the satellite/audio/video distribution gear physically which means that with the vertical displacement and routing around the central courtyard we are reasonably close to 250' cable length.

From the A/V closet there is another run of analog back the full 250'(ish) feet where it goes through two passive splitters with one line running another 50 feet to the front of the chapel, and the others running about 20, 25, 50 and 100 feet to various other points in the building all of which have F connectors.

First problem: the video quality of the new D70 is great - when viewed on the monitor attached to the distribution system in the closet. By the time the signal is sent back through the 30+ year old wiring the degradation is evident.

Will this make the problem go away?
http://www.amazon.com/BVAM7-7-Out-Video-Signal-Amplifier/dp/B000LP4RF8


Second problem: On the opposite side of the chapel from where the video input is located is a 2nd floor cry room with a glass bay window overlooking the chapel. This is located about 50-60' away horizontally and about 12' vertically away. This is the logical place to seat the camera operator as he can watch the proceedings and control where the camera is pointing. Yet another link to the video output tangle will have to be routed to this room so he can actually monitor the video stream that he is controlling.

They are going to want to be able to put the lyrics of the hymns up on the TVs and projectors during conference so there needs to be a way to switch between video sources (probably between camera and laptop). I am guessing that I will have to route the video input feed through that room and then back to the A/V closet (extending the distance accordingly).

Will this make the problem go away?
http://www.amazon.com/exec/obidos/ASIN/B0014KOAD8/ref=nosim/

russellhltn
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Postby russellhltn » Thu Feb 16, 2012 12:41 am

aclawson wrote:There exists a chapel with a video point of input in the wall of the overflow. This port accepts cables with a composite (RCA) termination.

The other end of this run is just under 170' from the satellite/audio/video distribution gear physically which means that with the vertical displacement and routing around the central courtyard we are reasonably close to 250' cable length.

From the A/V closet there is another run of analog back the full 250'(ish) feet where it goes through two passive splitters with one line running another 50 feet to the front of the chapel, and the others running about 20, 25, 50 and 100 feet to various other points in the building all of which have F connectors.

First problem: the video quality of the new D70 is great - when viewed on the monitor attached to the distribution system in the closet. By the time the signal is sent back through the 30+ year old wiring the degradation is evident.

Will this make the problem go away?
http://www.amazon.com/BVAM7-7-Out-Video-Signal-Amplifier/dp/B000LP4RF8


Probably not. You're missing a critical part of the picture. In the A/V cabinet, the signal is being converted from baseband video to RF and sent back out the distribution system.

You didn't say what the picture looked like, or confirm that you are using RF in the distribution system. What might be happening is that the signal from the modulator is getting weak by the time it reaches the destination. Or it might be the channel used is the same as one in your area (not likely since the switch to DTV, but possible.)

How are you monitoring it at the A/V closet? Video or RF?
Have you searched the Wiki?
Try using a Google search by adding "site:tech.lds.org/wiki" to the search criteria.

aclawson
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Joined: Fri Jan 19, 2007 6:28 pm
Location: Commerce Twp, MI

Postby aclawson » Thu Feb 16, 2012 5:31 am

RussellHltn wrote:You didn't say what the picture looked like


Grainy, a few flickers - it looks like a degraded video signal. On all channels. (3 for satellite/english, 6 for in-house video, 10 for satellite/spanish.) In all cases the picture looks better in the A/V closet than anywhere else.

What might be happening is that the signal from the modulator is getting weak by the time it reaches the destination.


Exactly - which is why I'm looking for an amplifier.

How are you monitoring it at the A/V closet?


TV gets attached to the video distribution's monitor port with a piece of coax then tuned to either 3, 6 or 10.

marcporter
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Joined: Thu Feb 17, 2011 1:52 pm

Postby marcporter » Thu Feb 16, 2012 9:49 am

The Amplifier you linked to is a baseband amplifier (also known as composite or RCA video) This is what the camera is sending and is what is being received into the modulator from the camera (not the signal that you are trying to improve.) The signal that is being degraded is the signal coming out of the modulator which is now RF. http://www.amazon.com/Blonder-Tongue-1464-DISTRIBUTION-AMPLIFIER/dp/B0034IRWK6/ref=sr_1_4?ie=UTF8&qid=1329410728&sr=8-4
Keep in mind that these systems are usually tuned to cable lengths, number of taps, type of equipment, etc. I would work with your FM group to get the signal improved, since the closed circuit distribution system is part of their responsibility. There is likely already an amplifier on the system, it might just need to be retuned.

russellhltn
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Postby russellhltn » Thu Feb 16, 2012 10:19 am

marcporter wrote:There is likely already an amplifier on the system, it might just need to be retuned.


In our system, the modulators are the "amplifier" and it's fed to a passive combiner. Previously, there was a active distribution amplifier.
Have you searched the Wiki?

Try using a Google search by adding "site:tech.lds.org/wiki" to the search criteria.

marcporter
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Joined: Thu Feb 17, 2011 1:52 pm

Postby marcporter » Thu Feb 16, 2012 10:27 am

In the case where the modulator is the amplifier, there is some adjustments that can be made on the modulator to improve the output signal. It could also be that the cabling (the older buildings were RG59) is the weak link and needs to be upgraded to modern RG6Q.

michaelfish
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Location: Gilbert, AZ USA

RF Splitter vs Tap

Postby michaelfish » Thu Feb 16, 2012 11:11 am

the video quality of the new D70 is great - when viewed on the monitor attached to the distribution system in the closet
So the problem is not with the composite video signal from the camera to the A/V cabinet. You reported the degraded signal is on the TV reception side (RF).

I agree with the suggestion marcporter made; it is very possible the RF amplifier in the cabinet simply needs to be adjusted.

Another possiblility may be the incorrect use of splitters instead of taps. We had similar problems with weak TV signals in our building and I discovered that splitters were used, when taps should have been used instead. Splitters are sometimes incorrectly used when distributing signal. See this diagram.

Splitter vs Tap.jpg
Splitter vs Tap.jpg (19.35 KiB) Viewed 631 times


I don't know if your building is using taps and splitters, but it is something you may want to investigate. The proper use depends on the layout.

Again, the FM group should be able to help you with this.

Another possible cause of the deteriorating signal may be a poor terminations. For instance, sometimes a wire from the braid of the coax may have been wrapped around the center conductor causing a short and loss of signal. It wouldn't hurt to cut off the old connectors and replace them.


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