Mariusz SP3FXC writes:

__ ________ _____ __
__| |__| |__| |________|
0 0 0 1 1 0 0 1 0 1 1 0

Very good One more question. Is it "level-sensitive" coding? I mean if we
change the phase (by 180deg.) of NRZI coded signal would it be still
readable when it hits decoder? I need to verify this because it is
essential for my project.

Look at the diagram. A zero is a change in state; doesn't matter
in which direction it changes. If you invert the input signal the
output is still the same:

__ ________ _____ __
__| |__| |__| |________|

-- -- -- --------
|__| |________| |_____| |__

0 0 0 1 1 0 0 1 0 1 1 0

Same output.

// marc