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The performance of a telegraph system using error detection and automatic repetition of signals is analyzed for several fading and noise conditions. At first the effect of the decision feedback is calculated-the number of errors and the transmission speed as a function of the character error probabilities. The properties of the code give the character error probabilities expressed in element error rate. The error probabilities are calculated for several detectors and fading models as a function of the signal-to-noise ratio. Using these results the behavior of the whole system is computed and graphs are given of the transmission speed and the number of undetected errors as a function of the signal-to-noise ratio. The analysis shows that with the system considered, the number of errors can be made as low as desired, for all circumstances, including interruptions. This cannot be obtained with a system using error correction. Finally some simple equations are given for the most important points of the curves.