On Wed, 1 Jun 2011 20:18:06 -0700 (PDT), "
wrote:

Putting an amp at the dislay end just amplifies signal plus noise, it
must be closer to the camera so that it only amplifies signal and not
noise.....

It's not a S/N problem. It's the change in group delay across the
video frequency range that's distorting the parts of the NTSC video.
Throw in a -6dB/octave loss to trash the amplitude. See the photos
near the bottom of:
http://www.intersil.com/data/fn/fn6739.pdf

Instead of an adaptive equalizer, it can be done with a passive
equalizer, followed by an amplifier to compensate for the losses. The
adaptive equalizer adjusts itself, while the passive equalizer and amp
design requires level adjustment. When something changes in the
cabling, the levels need to be re-adjusted.

Typical video distribution amplifier:
http://www.multidyne.com/amps.html
Claims "3000 feet of Belden RG59U to within +/-0.05dB at 5MHz".
Probably overkill for a security camera.

This design works to 250ft. More amplifier gain will be required for
1500ft.
http://cds.linear.com/docs/Design%20Note/dn92.pdf

Here's another example. Claims 1000ft or mo
http://www.decadenet.com/cab/cab.html

--
Jeff Liebermann
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Santa Cruz CA 95060 http://802.11junk.com
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