Comparative Mathematical Study of Signal-TO-Noise Ratios of Several Modulation Methods in Digital Transmission . Vergleichende Mathematische Studie der Stoerabstaende Verschiedener Modulationsarten bei Digitaluebertragung

摘要

Several modulation methods for the transmission of high speed digital data over a transmission channel with certain properties (AM, SSB, FM and 4 and 8 PM) are compared regarding signal to noise ratios and distortion. By computerized simulation, pulse series at the end of a telephone transmission are calculated and the resulting time distortion, as compared to a fixed frame and amplitude or phase distortion, are statistically evaluated. As a result the necessary signal to noise ratios for several threshold values of amplitude and phase are determined. A big difference in the different modulation methods is not found. Only for the 8-phase modulation the necessary S-N ratio is higher as a result of the lower threshold distance.