Linearization of Nonlinear Systems.

Progress is made in a detailed study of the problem of low crest factor signals, based on the techniques used earlier work harmonic probing of nonlinear systems. Particularly interesting here is the numerical evidence suggesting that the phases used in the original work exceed the performance achievable with the Shapiro-Rudin phases, which can be proved to yield bounded crest factor for multitone signals containing an arbitrarily large number of tones. This work has practical application for frequency response measurements of linear system, and of course is critical for measurements of small distortions in nonlinear systems. Perhaps the most exciting area of progress is in the design of an adaptive linearizing compensator for a slightly nonlinear system. A preliminary design has been proposed, and recently the first full simulation results showed typical distortion nulling by a factor of 10 -20dB for some simple nonlinearities. Of course these are preliminary results, and much more needs to be done, but basic feasibility has been demonstrated.