Specifications

There is another condition that can occur that will have devastating effects
on a fiber systems output. This problem is one that affects older established
systems, if the system was working and begins to cause problems, look at the
levels at the output of the fiber system.
If the Sync signal is unusually high (over 50 I.R.E. units) it may be possible
that the internal 75 Ohm termination has been damaged by a lightning storm or
other high voltage ground-loop related occurrence. Lightning storms can cause a
permanent increase in the termination resistance or a removal of the termination
completely. This will cause the video level to go up radically and if the camera
cannot deliver a total of 240 I.R.E. units or the clamp and AGC (automatic gain
control) inside the fiber unit cannot handle the increased level then the output level
of video will be corrupted.
THE SOLUTION:
Careful measurement and setting of the video levels originating from the
camera is the best way to solve the problem caused by the clamp in the fiber optic
equipment. You should have a way of measuring video levels of both the Sync
and Luminance levels to properly determine the extent of the problem and to set
the camera correctly.
TOOLS:
If you do not currently have a way of measuring video levels a meter that
allows you to measure the Sync and Luminance is a must. One meter that meets
this goal is called a CM-2 Camera Master. It will measure the Sync, Luminance,
Composite, Color Burst, Focus, and Ground Loop on any video signal. It is battery
operated and portable. It is also small enough to take up a ladder to set up any
camera. It is manufactured by FM SYSTEMS, INC. Santa Ana, CA. 800-235-6960.
A HELPING HAND.
If you cannot isolate the problem and resolve the interference then please
contact me at: 800-235-6960 my name is Don McClatchie and I would like to talk
to you about your specific problem. Together we can find the solution to your
problem.
CCTV TRAINING MANUAL PAGE 28 OF 28