Generation of Linear and Nonlinear Synchronous Data Signals by Digital Echo Modulation in a Time-Varying Transversal Filter

It is shown that under certain moderate conditions, a large class of passband data signals, including all two-dimensional signal sets and many multilevel frequency-shift keying (FSK) signals, can be constructed from a finite set of stored waveforms. A description is given of a transversal filter with time-varying tap weights which can generate this class of signals. The configuration is amenable to digital implementation and to use in program-controlled systems.