Non-linear memory effects and digital communications in a simplified yjystron configuration

Summary form only given. Simulations of transmitters in communications systems typically employ a simplified series block model to describe the response of the amplifier. Such a model consists of a linear, frequency-dependent block to describe the complex frequency response, cascaded with a nonlinear, frequency-independent block to account for the saturation effects on amplitude and phase. Such models are generally adequate for modeling the behavior of digital communication signals passing through the amplifier when the data rate and the nonlinearity are not simultaneously large. Klystrons are widely used in communication applications, in particular for microwave ground links and satellite uplinks. The nearly saturated condition in klystrons is desired for high efficiency, which can exceed 70%, and the use of multiple phase-shifi-keying (m-PSK)between equal amplitude digital symbols avoids the most obvious problems with nonlinearity. However, nonlinear memory effects,which cannot be described by the series block model, can occur in klystrons operated near saturation under high data rate conditions. Such effects will lead to excessive system bit error rates unless they are properly modeled and accounted for in the system design.