Abstract: A front end for a broadband optical receiver is disclosed which includes a monolithic integrated Darlington circuit with bipolar transistors (T1, T2). This Darlington circuit is a simple integrated amplifier (OP) developed for UHF application in the range between 0 and 2 GHz. By connecting a suitable transimpedance resistor (R.sub.T) across the Darlington circuit, an improvement in linearity is obtained such that the Darlington circuit can be used together with an avalanche photodiode (APD) in the 0- to 5-GHz frequency range, and together with PIN diodes in short-and medium-length optical tansmission links.

Abstract: In a broadband private automatic branch exchange (BB-PABX) in which a plurality of broadband terminals (BB-E1, . . . , BB-E26) are connected to a broadband switching array (BB-V) to switch video and data signals, the current call status of the system must be signaled to the terminals, so that a broadband connection may be activated. For this purpose, a message characterizing a quiescent state is supplied to one input/output (O) of the broadband switching array (BB-V) of the private automatic branch exchange and all nonswitched input/output (1, 2, . . . , 30) controlled by an associated control unit (C) are linked with the first input/output (O) so that the quiescent state message is always transmitted to all nonswitched terminals.

Abstract: An image signal (V1) is transform coded in a Discrete cosine Transform Coder (DCT) and the output coefficients thus provided are encoded in a zonal encoder (QZ). The output of QZ is inversely coded (IQZ) and substracted from the coefficients of the DCT. The resulting error is encoded in an entropy encoder. Both the zonal coder and the entropy encoder have quality inputs (TZQ, TEQ) controlling the compression factor, and have their outputs combined in a single compressed data stream (TXD3).

Abstract: An organic material for non-linear optics comprising:an electron donor group constituted by a heteroaromatic cycle;an electron attractor group selected from NO.sub.2 and CN; andan electron effect transmitter group selected from an aromatic system of the phenyl ring type, or a chain having n atoms of carbon including a double or a triple bond (n<4).

Abstract: A modulator suitable for 16 quadrature amplitude modulation (QAM) is designed as a double modulator (1), wherein a 16 QAM modulator (39) consists of two double modulators (1). One double modulator (1) has two partial modulators (1',1") forming a bridge. Each partial modulator (1',1") has two possible transmission paths: (6',6") with a phase delay line (39',39") which causes a 180.degree. phase shift. On each of the two paths (6',6", 7',7"), a semiconductor diode (D.sub.1 ',D.sub.1 ",D.sub.2 ',D.sub.2 ") is disposed in such a way that they provide the carrier (U.sub.c) with a 180.degree. phase inversion and are accordingly rendered conductive in unison, if no modulation voltage (U.sub.m) is applied, whereby the carrier is suppressed at the signal output (3'). When a modulation signal (U.sub.m) is applied, the balance is changed to push-pull, and one of the two paths (6',6") assumes less impedance compared to the other path (7',7"), which leads to the generation of the modulated carrier voltage (U.sub.mc).

Abstract: The composition of material being grown by vapor deposition may be analyzed in situ by applying a beam of electrons, from a source such as a RHEED gun, incident at a low angle to the material being grown. The energy levels in the reflected beam may be analyzed by spectroscopy to qualitatively and quantitatively the presence and absence of elements, as well as their ratio, by analysis of the number of electrons at energy levels related to core level transitions representative of specific materials. Such compositional analysis may be used in real time to control the deposition growth process.