Deutsche Itt Industries Gmbh

Itt Industries, Inc.

Heinrich Pfeifer

Werner Reich

Ulrich Theus

Soenke Mehrgardt

Peter M Flamm

Martin Winterer

Thomas Hilpert

Thomas Fischer

Sonke Mehrgardt

Rainer Schweer

Sound channel circuit for digital television receivers

In a pulse-density D/A or A/D converter, improved averaging of a pulse-density-modulated (PDM) signal in the presence of a jittering clock signal is achieved by applying the PDM signal to the serial input of an n-stage shift register whose parallel output serves to control n state signals. The shift register is driven by the clock signal. The n state signals are combined into a sum signal which feeds a low-pass filter. In preferred embodiments, the n state signals are weighted and/or isolated from the respective previous state and the following state by means of gate circuits.

Circuit arrangement for averaging signals during pulse-density D/A or

To realize the transfer function in a digital filter circuit:

Digital decimation filter

To raise the integration level of a video recorder, and to provide a uniform circuit concept suitable for all three color-television standard (PAL, NTSC, SECAM) which, in particular, requires only slight modifications for adaptation to the respective standard, signal processing is performed by fast digital circuits whose signals are stored on the recording medium not in digital form, but after digital-to-analog conversion. The composite color signal is converted into digital form by a fast analog-to-digital converter (aw) whose sampling signal (fc) has a fixed frequency (Fc) for all three color-television standards. Digital signal processing in the chroma channel is performed at a fixed subcarrier frequency (zt) for all three color-television standards which is an integral subharmonic of the sampling frequency (Fc).

Video recorder with a magnetic recording medium in the form of a tape

A digital frequency demodulator circuit works on the principle of determining the number of zero crossings of a band-limited input signal in a given period of time, in corresponding prior art analog circuits. The circuit includes an analog-to-digital converter, three delay elements, two edge detectors, an up/down counter, two arcsin read-only memories, a 1/2 multiplier and a multiple adder.

Frequency demodulator circuit with zero-crossing counter

An essentially digital circuit is disclosed in which a demodulated broadcast signal is digitized by an analog-to-digital converter and processed in three signal paths each including a tuned filter. The tuned filters have closely adjacent resonance frequencies, the same resonance curves, and the same resonance rises. The signals at the outputs of these three signal paths are so evaluated by means of four comparators and an RS flip-flop that the message tone signal appears at the Q output of the flip-flop only in the presence of the message tone frequency.

Circuit for decoding traffic information message tone signals

A circuit for decoding broadcast traffic area signals according to the European standards utilizes digital circuitry to check for four criteria.

Growing community of inventors

Denzlingen, Germany

Heinrich Pfeifer