I don't have a 1881 application in front of me, but did you make sure
that:

1. It is coupled to the video signal using a capacitor. 2. That the input
pin is connected to Vcc or Gnd through an appropriate resistor (or not at
all) at the chip as required by the application note. 3. That the video
signal line is terminated into 75 ohms at all times.

#3 means that you put a seventy-five ohms resistor between the signal line
and gnd near your project, *unless* the video signal continues to another
device that is specifically designed to receive a video signal (and has
the 75 ohms load inside). Better professional grade units have a
feedthrough style video hookup with two BNC connectors and a switch that
turns on the 75 ohms at will.

In my experience the even/odd signal out of a 1881 is fairly reliable, but
do not expect miracles. I once had trouble with cameras that were
occasionally exposed to very strong light. This made the 1881 go
temporarily crazy and miss a few frames. The problem was really the cheap
analog processing (and clamping) in the cameras.

If you have this sort of trouble you can divide the video signal going
into the 1881 using a resistive divider to about 70%. The 1881 will still
work right but major camera overloads will be ridden out better (however
this reduces the tolerance for lower sync levels).

Peter

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