Abstract: A stereophonic audio signal processing arrangement for variably enhancing a stereo image, wherein the stereo image enhancement is reduced at high signal levels so as to reduce distortion. The arrangement is used in a stereophonic audio reproduction system for enhancing the stereo image, which system may be part of an audio-visual reproduction system.

Abstract: Known is a telecommunications system comprising a near end and a far end subscriber unit communicating with each other via a transmission channel, at least the near end subscriber being arranged for handsfree communication. In the known system, the near end subscriber unit comprises a duplex controller controlling the near end subscriber unit to three stable modes, a transmit mode, a receive mode, and an idle mode. The known subsciber unit operates in half-duplex mode and has speech and noise detectors for the transmit and receive paths, and a speech level comparator controlling the mode switching. At mode switching, suitable gain adaptation is done in the transmit and receive path so as to prevent howling in handsfree mode. The known duplex controller does not operate satisfactorily if the near end speaker is at a relatively large distance from the microphone. A telecommunications system is provided that satisfactorily operates when the near end speaker is a relatively large distance from the microphone.

Abstract: A power-supply and communication circuit is based on a flyback converter with a transformer (6) whose primary winding (10) is periodically connected to a supply voltage by means of a switching element (8) in the rhythm of control pulses from an oscillator (24). Data communication to the secondary electronic circuitry (4) is effected by interrupting the control pulses in response to a first data signal (SDTA1) to be transmitted. The absence of the alternating voltage across the secondary winding (18) is detected by means of a peak detector (28) and converted into a received first data signal (RDTA1). Data communication to the primary electronic circuitry (2) is effected by actively modulating the rectified voltage at the secondary side by means of a modulator (30) in response to a second data signal (SDTA2) to be transmitted. The resulting fluctuations in the flyback voltage across the primary winding are detected by means of a second peak detector (32) and converted into a received second data signal (RDTA2).

Abstract: An audio amplifier having a volume-dependent tone control which is inexpensive and hardly distorts the audio signal. A filter in the signal path of the audio amplifier determines the tone control at low volumes. The bass tones and possibly treble tones are then amplified to a greater extent than the mid-range tones. With an increasing volume, a continuously controllable amplifier stage increasingly compensates this tone control. To this end a linear feedback path is arranged across this amplifier stage, with a pole in or near the frequency range of the bass and mid-range tones.