Computer modeling of multiplechannel input signals and intermodulation losses caused by nonlinear traveling wave tube amplifiers
Abstract
The multiple channel input signal to a soft limiter amplifier as a traveling wave tube is represented as a finite, linear sum of Gaussian functions in the frequency domain. Linear regression is used to fit the channel shapes to a least squares residual error. Distortions in output signal, namely intermodulation products, are produced by the nonlinear gain characteristic of the amplifier and constitute the principal noise analyzed in this study. The signal to noise ratios are calculated for various input powers from saturation to 10 dB below saturation for two specific distributions of channels. A criterion for the truncation of the series expansion of the nonlinear transfer characteristic is given. It is found that he signal to noise ratios are very sensitive to the coefficients used in this expansion. Improper or incorrect truncation of the series leads to ambiguous results in the signal to noise ratios.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 May 1982
 Bibcode:
 1982STIN...8225441S
 Keywords:

 Intermodulation;
 Mathematical Models;
 Signal Distortion;
 Traveling Wave Tubes;
 Approximation;
 Computerized Simulation;
 Gauss Equation;
 Nonlinear Systems;
 Signal To Noise Ratios;
 Sound Amplification;
 Electronics and Electrical Engineering