Abstract: A coding method for multichannel optical transmission systems (10) is described, in which coding is carried out both in the time direction and over a plurality of channels, a mapping being selected for the coding such that the simultaneous occurrence of bits with a signal value of ‘1’ in neighbouring channels is excluded. A multichannel optical transmission system for carrying out the method is furthermore described, as well as a coder (12) for use in conjunction with such a multichannel optical transmission system (10).

Abstract: A digital filter having K coefficients h(k) processes code words x(n-k), represented in the binary codes, of an input signal bit-parallel and uses filter coefficients h(k) represented in the CSD code. Substituting in the filter equation ##EQU1## the representation of the coefficients in the CSD code and the representation of the input code words in the binary code, the problem of converting a linear combination of powers of two, having arbitrary integral coefficients, into a binary number will occur repeatedly. Carrying out this conversion by means of cascades of Wallace Trees terminated by adders for two binary numbers results in a digital filter that is suitable for sampling rates up to 20 MHz and that can also be realized without any difficulty when an excess of 25 coefficients is needed for adhering to the required filter characteristic.

Abstract: In the hybrid encoder for video signals described the picture elements of a video picture are arranged into equally large data blocks and each newly entered data block, is compared with a data block of the previous video picture by means of a subtractor (SR). The data blocks of the previous picture are stored in a picture store (BS). In order to maintain the transmission bit rates as small as possible, the data blocks are conventionally subjected to a transformation (for example, a Fourier transformation) (F) and a subsequent quantization (Q). For the required strong bit rate reduction a rough quantization is necessary, which leads to a strong quantization noise. To eliminate the quantization noise a blockwise adaptive low-pass filtering (T,FTI) is performed in two signal paths of the hybrid encoder. The quantizer (Q) may then have a refined design or it may be omitted altogether.

Abstract: A method and apparatus for equalizing a scanned noisy digital signal with an automatic and adaptive decision feedback equalizer comprising a nonrecursive part and a recursive part. A switch is disposed in the feedback loop of the equalizer between a decision device and the recursive part of the equalizer for allowing the determination of a step size factor. For this purpose the switch is in such a position that a reference signal can be fed into the feedback loop and at the same time the gradient coefficients are fed to a device for setting the filter coefficients. The gradient coefficients are determined at that point in time where the switch was set to the other switch setting. The number of the required interation intervals to approaching the minimum of the equalization error can be decreased by employing the method of the present invention. In addition, the filter configuration can be employed in a multiplex operation.