The signalimessignal, noiseimesnoise, and signalimesnoise output of a nonlinearity

The signal
\times
signal, noise
\times
noise, and signal
\times
noise output components of a nonlinearity are defined in a manner agreeing with intuition. The definitions are shown to accord with previous usage, for which they now provide a clear meaning. The case of a limiter is used as an illustrative example. The approach is applicable not only to fixed memoryless transformations but also to nonlinearities with memory that depend explicitly on time, such as frequency or phase modulation, demodulation, and bandpass nonlinearities.