Abstract: In a process for signaling an interruption in the state of readiness of a data terminal device in a called station, the data being transmitted over a data selector network, and in particular for teleprinters, following the establishment of a connection, the calling station requests the called station to transmit identification by way of the data selector network. Following reception of the identification assigned to the called station, the data transmission begins and upon the occurrence of disturbances which interrupt the state of readiness for reception in the called station, a monitoring circuit responds. For the duration of the interruption of the state of readiness the monitoring circuit blocks the identification keyer in the called station from transmitting the identification assigned to the called station and the monitoring circuit automatically clears the connection.

Abstract: A method is described for establishing character frame synchronism between a teletypewriter transmitter and receiver wherein the direction of transmission is unidirectional. The transmitter sends character signals identifying characters of the alphabet or the like and operating condition signals corresponding to the operation condition of the transmitter. The operating condition signals are processed in a code converter which allocates code words to them permitting recognition of the character frame. The code words are transmitted to the receiver wherein a clock signal is derived by means of a character frame discriminator. The code words are reconverted in the receiver in order to cancel the code conversion which took place at the transmitter.

Abstract: Apparatus for selecting a diversity channel in a data processing system is described. Data from a data source are assigned a signal whose binary values change within a given test period. At the receiver, a test device produces test signals indicating parameters of the received signals, and in dependence upon the test signals one of the diversity channels is connected by a channel switch to a data sink.