Sgsates Componenti Elettronici S.p.a.

Vittorio Comino

Marco Siligoni

Vanni Saviotti

Ferdinando Lari

A telephone circuit which may be monolithically integrated, for generating control signals for displaying the telephone charges to a telephone user, is coupled to a AC voltage signal generator having a predetermined amplitude and frequency which are constant over time. The circuit includes a voltage generator for generating voltage signals which are spaced over time and have a trapezoidal pulse waveshape. A multiplier circuit calculates the product of the signals supplied by the two generators and supplies a signal which is sent to the speech circuit of the subscriber's line and is added to the speech (i.e.--conversation) signals. The circuit also includes a circuit for receiving an image signal of the overall signal adapted to the telephone line; a high-pass filter for eliminating the speech signal components from the image signal; a rectifier circuit for rectifying the filtered signal and a comparator for comparing the rectified signal with a reference signal. If the amplitude of the rectified signal is greater than the amplitude of the reference signal, the comparator generates a signal designed to stop the increase in the level of the trapezoidal pulse signals generated by the voltage generator thereby regulating the amplitude of the trapezoidal pulse signals.

Growing community of inventors

Turin, Italy

Vittorio Comino