Certain Factors Affecting Telegraph Speed

Abstract

In considering methods for increasing the speed of telegraph circuits, the engineer is confronted by the problem of transmitting over a circuit the maximum amount of intelligence using a given frequency range, without causing undue interference, either in the circuit being considered or from that circuit to other circuits. In this paper the following two fundamentally important factors in connection with this problem are given principal attention: 1. Signal shaping, i. e., giving signals the best wave shape before impressing them on the transmitting medium so as to be able to send signal elements at maximum speed without undue interference into other circuits. 2. Choice of codes so as to transmit the maximum amount of intelligence with a given number of signal elements. These factors are discussed with the idea of indicating the best methods, as well as to give an idea of what may be expected from these methods. In connection with the choice of codes, consideration is given to the effect of codes differing in the number of ``currentt values'' employed. By this is meant the number of different current values which are employed in a system in forming the different characters.