Abstract: Digital signal processing arrangement such as a digital filter for computing output signal samples which are each equal to the sum of products of a given plurality of pairs (for example N) of input signal samples. One of the input signal samples of the pair is, for example, formed each time by a sample x(n) of a digital signal to be filtered, the other input signal sample of the pair by a filter coefficient z(n), wherein either the sample x(n) or the filter coefficient z(n) can assume only a limited number of values 0, .+-.A.sub.1, .+-.A.sub.2, . . . .+-.A.sub.M, M being much smaller than N. In the case x(n) can assume only this limited number of values, z(n) is first multiplied, owing to the x(n) belonging to the pair, by the sign of x(n) for generating a product of the form z(n). sgn [x(n)]. In-dependent of the magnitude of n(n) this product is applied to an accumulator which corresponds with this magnitude of x(n).

Abstract: In a videophone system sound, video, synchronizing and signalling signals are to be transmitted through a single pair of telephone cables of existing telephone communications. In that case sound, synchronizing and signalling signals are transmitted in a digital form and the video signals are transmitted in an analog form. It is then possible to achieve optimum picture quality at the given bandwidth of the existing telephone communications. If for the given bandwidth the video signal were also digitalized, this would be at the expense of the picture quality. However, it is then necessary to transmit information regarding clock pulses for decoding at the receiver end. To be able to synchronize at the receiver end only on two frequencies instead of on clock pulse frequency, line frequency and field frequency, the information regarding the clock pulses is cotransmitted in such a manner that a clock pulse generator at the receiver end can be synchronized therewith which generator supplies clock pulses.

Abstract: A digital data transmitter is described, whose line carrier frequency need not be an integral multiple of one half the clock frequency of the digital input signal. Use is made of a digital filter for increasing the sampling frequency to a value which is twice the modulator carrier wave frequency.

Abstract: A non-recursive interpolating digital filter for generating, output code works, at an arbitrary rational ratio between the input and output sampling frequencies. The input code words are entered and stored in a buffer, and entered into a storage device at predetermined times determined by a controlled pulse generator.