Nonlinear dynamical systems possessing an invariant subspace can display in
teresting dynamical behavior, such as on-off intermittency and bubbling. Th
is Rapid Communication shows that a class of such systems has amazing featu
res of (1) supersensitivity to small input signals and (2) robustness of th
e supersensitivity in the presence of noise. These features make the system
s very promising as small si,anal detectors. [S1063-651X(99)50206-7].