In recent work we have shown how one chaotic system may be synchronize
d with another by sending a signal from one to the other. In this pape
r, we demonstrate the cascading of synchronized chaotic systems. Such
cascading allows the reproduction of all of the signals in the origina
l chaotic system using only 1 signal. This configuration may be used a
s a ''chaos filter''. We also are able to vary a parameter in one chao
tic system and, using only the chaotic signal, cause the corresponding
parameter in another chaotic system to track these variations. This i
s a chaotic analog to a phase locked loop.