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Author Topic: CCTV Upgrade BEFORE Christmas  (Read 6741 times)

Ed Baumann

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CCTV Upgrade BEFORE Christmas
« on: December 06, 2010, 02:32:08 pm »

Greetings!

I'm the Director of Facility and A/V Resources at a church just outside of Washington, DC. We have 1500 - 2000 members and a decent sized facility. After years of the AV team pushing to upgrade our CCTV system (parts are 20 years old) and hearing a constant "no" I was just notified that I need to come up with a plan to pipe video to our Fellowship Hall on that system for overflow on Christmas Eve. I need help to come up with a plan before meetings tomorrow. Here's my info:



We have an Arm Electronics security camera as our only video input (not sure which model, just that it operates on RS-485, and can't be more than 480 lines of resolution).

This feeds a powered splitter that then feed a newer Blonder-Tongue analog modulator (BAVM series).

The audio input pulls off of a matrix output from our Allen & Heath mixer running through a Protea digital crossover.

From there is goes into an apartment complex grade signal amplifier that then feeds a passive F splitter (1:5) for the runs throughout the building.

The couple hundred foot run is with RG-6 quad-shield cable (what you get when the sound team does our own work instead of contractors).

This goes into a Blonder-Tongue agile demodulator (model unremembered).

The video and audio are split out to an Extron video switcher, video goes to projector to 15' screen, audio goes to amp to main speakers (EAW something or others).


The video quality looks bad. I thought the head pastor was speaking on Sunday when I tested, came to find out we had a guest preacher. The audio quality is poor, I have background noise/hum and a distorted quality to the overall sound.

I'm looking for advice on improving signal quality (likely video equipment needed) and fixing the audio (likely a fix for me to perform). Budget is twofold. I need as cheap as I can get it done for Christmas. As well as a long term "here's the right way to do this sort of video work" budget that is less dollar constrained.

Any and all help is appreciated.

Ed Baumann
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Arnold B. Krueger

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Re: CCTV Upgrade BEFORE Christmas
« Reply #1 on: December 07, 2010, 08:46:55 am »

Ed Baumann wrote on Mon, 06 December 2010 19:32



We have an Arm Electronics security camera as our only video input (not sure which model, just that it operates on RS-485, and can't be more than 480 lines of resolution).

This feeds a powered splitter that then feed a newer Blonder-Tongue analog modulator (BAVM series).

The audio input pulls off of a matrix output from our Allen & Heath mixer running through a Protea digital crossover.

From there is goes into an apartment complex grade signal amplifier that then feeds a passive F splitter (1:5) for the runs throughout the building.

The couple hundred foot run is with RG-6 quad-shield cable (what you get when the sound team does our own work instead of contractors).

This goes into a Blonder-Tongue agile demodulator (model unremembered).

The video and audio are split out to an Extron video switcher, video goes to projector to 15' screen, audio goes to amp to main speakers (EAW something or others).

The video quality looks bad. I thought the head pastor was speaking on Sunday when I tested, came to find out we had a guest preacher. The audio quality is poor, I have background noise/hum and a distorted quality to the overall sound.

I'm looking for advice on improving signal quality (likely video equipment needed) and fixing the audio (likely a fix for me to perform). Budget is twofold. I need as cheap as I can get it done for Christmas. As well as a long term "here's the right way to do this sort of video work" budget that is less dollar constrained.




The weakest link in this system is probably the use of a security camera as your primary video source. The hum in the audio may be due to a ground loop related to the video modulator or it may be due to poor tuning, gain staging and/or quality at the receiver end of the system.

One approach to diagnosing this is to take a divide and conqueor approach. How does the video display look when you use a DVD player as the A/V source as an alternative to the B-T demodulator?

If using the DVD player as a source for the video display is a tremendous improvement, then repeat the experiement by hooking up the DVD player at the sanctuary end of the system - connect it to the input to the B-T modulator.
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Ed Baumann

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Re: CCTV Upgrade BEFORE Christmas
« Reply #2 on: December 07, 2010, 09:40:15 am »

A DVD player comes out pretty well on most TVs around the church. On the far runs to the Fellowship Hall and a secondary room (both were tested with the same B-T de-modulator) the audio had the buzz and the video was perfect save for occasional signs of interference (lines across the screen like there's a tracking problem, a worse scratchiness to the audio). I'm afraid we may have made an antenna out of the long run (but RG-6 quad shield shouldn't have that problem...). This interference is NOT noticed on the short runs.

I'll check your suggestions for grounding issues. I've done my best shot at gain staging, but mainly through a trial and error approach.

I know this means we need a new camera (I'm pushing for a Sony EVI series, something designed for video work), still trying to work out the audio issue and video interference.

Ed Baumann
Director of Facility and A/V Resources
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Arnold B. Krueger

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Re: CCTV Upgrade BEFORE Christmas
« Reply #3 on: December 07, 2010, 11:07:01 am »

Ed Baumann wrote on Tue, 07 December 2010 14:40

A DVD player comes out pretty well on most TVs around the church.



That speaks well for the quality of the modulators and demodulators.

Quote:


On the far runs to the Fellowship Hall and a secondary room (both were tested with the same B-T de-modulator) the audio had the buzz and the video was perfect save for occasional signs of interference (lines across the screen like there's a tracking problem, a worse scratchiness to the audio). I'm afraid we may have made an antenna out of the long run (but RG-6 quad shield shouldn't have that problem...). This interference is NOT noticed on the short runs.



I don't think that you're looking at interferance pickup due to cable length or poor shielding. Let's face it, people run TV RF for 100s and even thosands of feet without problems, all the time.

Hum on the audio and horizontal bars on the video sounds like a grounding problem. The A/V equipment at that site may differ from other sites in that the other locations may just be TV sets while this location uses a demodulator, a projector and some kind of a sound system. I'll bet money that at least one of those pieces of equipment has a 3-wire grounding plug.

A RF ground isolator on the coax may help a lot. There are also audio and video ground isolators and they can help too, but dealing with the grounding problem that's associated with the RF cable may be the easiest, cheapest way to go.

A camera upgrade seems to be in the picture, and that's really outside my comfort zone. We use a Canon HV20 and it gets the job done. It would work even better if it wasn't 80-100 feet from the lectern and we weren't running everything at like max telephooto zoom.


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Jonathan Johnson

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Re: CCTV Upgrade BEFORE Christmas
« Reply #4 on: December 07, 2010, 10:58:00 pm »

Make sure all your RF connectors are tight. I've seen a slightly loose connector result in a really bad signal; tighten it up and suddenly everything looks great. (In other words, check the cheap fixes first!)
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Ed Baumann

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Re: CCTV Upgrade BEFORE Christmas
« Reply #5 on: December 21, 2010, 12:39:12 pm »

Thanks for the help. Ground hum eliminator was a great suggestion, and I found some bogus settings on the digital cross over to change back...
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