Abstract: A method for correcting image errors in the transmission of DPCM coded image signals provides that an error trail recognition is carried out at the receiving end and that the adulterated image signal values are replaced by already received and intermediately stored image signal values of the preceding television image or television half image.

Abstract: A method of correcting image errors in the transmission of difference pulse code modulated (DPCM) coded image signals, in which image signal values of only a small number of image lines are intermediately stored at the receiving end, provides an error trail recognition and the replacement of the adulterated image signal values by correction values.

Abstract: Method and apparatus for the correction of image distortion in the digital transmission of video signals, in which at the receiving end a comparison is made between the received signal values and estimated video signal values computed from adjacent video signal values. When a prescribed threshold value is exceeded by the amount of the difference between the video signal value and the associated estimated video signal value, the corresponding estimated video signal value is forwarded instead of the received video signal value. A feature of the present method and apparatus is their ability to distinguish edges of objects when there are sharp fluctuations in expected signal level values.

Abstract: A digital signal multiplex device has at least one multiplexer and at least one demultiplexer for pulse frames having a number of useful information channels. The transmitter has a data protection coder and the receiver has a data protection decoder. The data protection coder generates an error protection code and inserts the error protection information into one or more of the useful information channels or into whole-numbered portions of at least one useful information channel in the pulse frame. At the receiving end, the error protection information-containing portion of the signal is supplied to the data protection decoder, which recognizes and corrects errors in all or certain of the channels of the transmitted time division multiplex signal. In this manner, all or individual ones of the useful information channels, which may be utilized for data transmission, can be transmitted with a lower bit error quota without departing from the standardized hierarchy stages of data transmission systems.

Abstract: An analog/digital telecommunication subscriber station is connectible to a two-wire line and comprises a frequency multiplexer and a frequency demultiplexer for grouping and fanning an analog communication channel covering the telephone band and a digital communication channel lying above the telephone band. The station further comprises a hybrid for connecting the two-wire line into a four-wire line. The subscriber station is particularly characterized in that the two-wire line is terminated by a broad-band hybrid which is proceeded in the transmission branch by a frequency multiplexer which groups at least the analog communication channel covering the telephone band and the digital communication channel lying thereabove, and is followed in the receiving branch by a frequency demultiplexer which fans at least the analog communication channel covering the telephone band and the digital communication channel lying above the telephone band.

Abstract: The present invention relates to a communications transmission system wherein there is superposed, on the conventional analog telecommunication network, a digital network whose digital local exchanges are connected with digital subscriber stations. Both networks are interconnected between the analog and digital local exchanges by way of analog/digital converters and digital/analog converters. In each digital subscriber station, a data transmission is possible simultaneously with voice transmission due to an automatic sub-channel formation by means of a multiplexer and a demultiplexer. An arrangement is provided for data clock pulse recognition to determine at which bit rate the respective data terminal operates, and causes a suitable sub-channel for the data to be arranged with a bit rate which is obtained from the voice channel.

Abstract: A digital communications transmission system includes calling and called digital terminals which are interconnected with a two-wire line or a four-wire line by way of respective termination sets. Each terminal includes a transmitter, a receiver and a calling device. The transmission system is particularly characterized in that there is provided in the calling terminal a transmitter which transmits signals in a first frequency position and a receiver which receives signals in a second frequency position, while the called terminal includes a transmitter which transmits signals in the second frequency position and a receiver which receives signals in the first frequency position.