Abstract: The invention relates to a method for pinpointing an interruption in a link for transmitting digital signals between a first station and a second station on the basis of the times of occurrence of signal changes on the link. In accordance with the invention, the method is characterised by generating signal changes after the link has been restored. Preferably, the time of restoration is determined on the basis of data signals received, and a detection signal is fed to the link after the determination of the time of restoration. On the basis of the difference in time of observing restoration and of receiving a detection signal, the location of the interruption is determined. For this purpose, the length of the link need not be known.

Abstract: The invention relates to a method and device for converting data packets by coding or compression, source data packets being converted into transmission data packets. In order to achieve an optimal degree of filling of the transmission data packets, a data field of a transmission data packet according to the invention comprises only data of one logical channel. To this end, the compressed data of the logical channels are separately buffered in preferably parallel buffers. Reconstruction information is not incorporated in the data fields of the transmission data packets but, if necessary, is transmitted in advance. The invention is applied, in particular, in X.25 networks.

Abstract: The invention relates to a method for transmitting data in a processed manner on a communication channel, in which a first series (1) of data is converted into a second series (2) of data by means of a first operation (P), the second series (2) of data is transmitted on the communication channel and the second series of data is then converted into a third series (3) of data by means of a second operation (P.sup.-1). Check data (4) are formed on the basis of the first series (1) and are added to the second series (2). Subsequently, the integrity of the third series (3) is checked using the check data (4). The operations may comprise, respectively, data compression and data decompression. The check data are subjected to a protection operation (S) before they are added to the second series. Preferably, the method takes place at layer 3 of the so-called OSI model. The invention furthermore provides devices for using the method.