Abstract: An analog-to-digital converter is described for converting an analog-signal into a sequence of (b+a)-bit code words by means of a b-bit auxiliary analog-to-digital converter. To reduce the quantizing noise resulting from the requisite quantizing of the analog signal samples this analog signal is applied to an integrating network whose output is connected to an amplitude-limiting device which brings the integrated signal within the signal range of the auxiliary analog-to-digital converter, which in its turn produces a sequence of b-bit code words which are applied to a digital output filter via a cascade arrangement of an amplitude-restoration device and a difference network.Sampling pulses which occur at a frequency exceeding the Nyquist sampling frequency associated with the analog signal are applied to the auxiliary analog-to-digital converter.

Abstract: A digital-to-analog converter is described for converting (b+a)-bit code words into an analog signal by means of a b-bit auxiliary digital-to-analog converter. In order to reduce the quantizing noise introduced by the indispensible quantizing of the (b+a)-bit code words for obtaining the b-bit code words these (a+b)-bit code words are applied to an integrating network which has its output connected to an amplitude-limiting device which brings the integrated signal in the signal range of the auxiliary-D/A converter. The output signal of the amplitude-limiting device is now quantized and this quantizing signal is applied to the auxiliary D/A converter which produces analog output signal samples which are applied to, possibly, an analog output filter through a cascade arrangement of an amplitude-restorer and a difference network.

Abstract: A circuit for suppressing pulse-shaped interferences in an audio signal caused by scratches on a phonograph disc, comprising a signal processing section connected between an audio frequency input and an audio frequency output, comprising a noise suppressor having a control input; as well as a control signal section connected between the audio frequency input and the control input, said control signal section comprising a first threshold selection circuit connected to the audio frequency input for selecting pulse-shaped signals from the audio signal, followed by a second threshold selection circuit for distinguishing the pulse-shaped signals originating from noise signals from those originating from musical signals.