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How to transmit video/audio to overflow audtorium

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Reg from AB
How to transmit video/audio to overflow audtorium
on Jan 26, 2007 at 9:14:59 pm

The Principal of one of the high schools that I produce Grad videos for has asked me to set up a link from the Grad ceremony location (a church) to an overflow auditorium (nearby school gym), so people can watch the ceremony on a video screen.
Distance is in the 150 - 250 metre range.
I run three cameras at the ceremony. (I'm normally a one man band, but enlist help for the few three-camera shoots that I do.)
1) Connection - wire or wireless? What are my options for each?
Wire - What do I need in order to push picture and sound down the same cable (Coax?) Will I need to amplify the signal? How much quality will I lose over 150-250m?
Wireless - Outside broadcast equipment is big $$$$. So has anybody used equipment like the following? Although they're designed primarily for surveillance, would they be suitable - or am I merely smoking substances that some would like to acquire? :-)
Option 1...
(This unit has features I don't need)
Here are some specs their rep sent me. Unfortunately, I don't know which specs indicate the quality.
Transmitter Specifications
Frequency 2400-2483 MHz
RF Output Power per FCC part 15.249
Frequency Stability 0.005% PLL stabilized
Video Bandwidth 5.8MHz
Input Impedance 75 Ohms
Audio Input 1 Vpp line level
Input Impedance 600 Ohms
Bandwidth 50Hz-15kHz (3dB)
Data Connection RJ11 jack for connection to PC with software
Image Rejection >60dB
Adj. Ch. Rejection >20dB for adjacent channels, >90dB Ch1-4, >60dB Ch2-4, 3-1
Receiver Sensitivity -90dBm
Coding 32 bit code
Video S/N >40dB at -80dBm RF input signal, >45dB at -75dBm RF input signal
Audio Output 1.5 Vpp line level, typ.
Output Impedance 600 Ohms
Audio Output S/N >12dB at 85dBm RF input
He also sent me estimated range data, but this post is already long...
Option 2...
This is much more basic, and has a shorter range, but the price is much nicer.
If this kind of equipment is NOT suitable, can anyone point me to stuff that is?

2) "Director's Equipment" - the stuff I need for someone to switch among cameras for transmission to the school gym. I assume I'll need four monitors (3 source, 1 destination), a video switcher, cabling from cameras to this equipment, and cabling from this equipment to the projection equipment (via the wired or wireless link). Right? Wrong? Did I miss anything?

Would appreciate advice from anyone who's tried this. I suspect it's possible but not practicable, but wanted to run it by people more experienced than me before replying to the principal.
Thanks in advance (and sorry about long post)

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Doug Graham
Re: How to transmit video/audio to overflow audtorium
on Jan 26, 2007 at 10:19:37 pm

I've run a coax cable from a camcorder to a monitor over about 150-200 feet with good results, but I'm not sure about extending the cable run to 250 meters. Can you get a reel of coax and try it as an experiment before making a decision?

You're right about the live switch equipment. The Videonics MX-DV will show up to four images on a single monitor (at reduced frame rate) so you wouldn't need quite as many physical monitors...although individual monitors is certainly the best way to go. If your master VCR has an "antenna out" jack, you could connect your coax there for the remote feed.

Doug Graham

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Mark Suszko
Re: How to transmit video/audio to overflow audtorium
on Jan 29, 2007 at 1:59:18 am

The type of coax you use is important for this to work using composite video. The better cable with less resistance also costs a lot more. You will probably need to add a video distribution amplifier to boost the signal strength.

Other folks use twisted-pair telephone line, which is cheap and easy to lay down, with video baluns.

It could be possible to stream it from place to place using a high-bandwidth internet connection.

Wireless adds complications and lots of chances for interference; I would use that as a last resort.

What you are doing is technically called an IMAG setup. The live and stage events forum is full of guys who specialize in this, so i would re-ask your question over there.

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