Abstract: A receiver for high bitrate binary signals contains a soft decision circuit with three parallel deciders coupled to a 2:1 multiplexer. The three deciders have different threshold values and generate four potential states. The 2:1 multiplexer translates the four different states into a restored data signal and a reliability signal indicating the decision reliability.

Abstract: In a method of converting a serial data stream into a parallel data stream in a communications interface, wherein the serial data stream is demultiplexed to a given number of lanes (11-14) and a sync header (24-27) is prepended to at least one data block (20-23) of at least one lane (11-14), for at least one lane (11-14) a sync word containing one or more bits, excluding the static word 01 as sync header, is given or generated and at least part of the sync word is used as sync header (24-27), which is prepended to the at least one data block (20-23). This allows for improved de-skewing.

Abstract: A filter for determining the cross-correlation of optically transmitted signals is disclosed which comprises a ladder structure of amplifier cells 3 and multipliers 4. Such a filter structure is integrated into a receiver for optical signals, the receiver being adaptable to the conditions of the transmission link through a recursive algorithm.

Abstract: Part of the invention is a method of generating an optical MSK signal comprising the steps of generating an optical signal using a laser using a NRZ-signal with a defined bit rate and a sinusoidal signal with half of the frequency of the bit rate to modulate the optical signal. A further part of the invention is a method for precoding the bit stream, wherein a differential precoder in combination with a coder is used for inverting the bit of the bit stream in using a predefined pattern.

Abstract: Part of the invention is a method for electronic equalizing an optical transmitter comprising the following steps.

Abstract: To transmit a digital signal over an optical fiber link, the digital signal is modulated onto an optical carrier using frequency shift keying modulation at a modulation index of h<0.5. Under the impact of a non-linear transmission effect in the optical fiber, the use of a modulation index h<0.5 leads to an increase in maximum permitted launch power of the optical signal, increased receiver sensitivity and an increased spectral efficiency.

Abstract: An input circuit, in particular for a multiplexer, for phase controlling of a data input signal with a clock signal, comprises a flip-flop, wherein the data signal is fed to a clock input of the flip-flop and the clock signal is fed to the data input of the flip-flop, and wherein the data output of the flip-flop is used as a control signal of a locked loop. An advantage of the invention is, that it is of simple design which makes the invention especially useful for high frequencies. The data output of the flip-flop is dependent on the phase relationship of the data input signal with respect to the clock signal.

Abstract: A receiver for high bitrate binary signals contains a soft decision circuit with three parallel deciders coupled to a 2:1 multiplexer. The three deciders have different threshold values and generate four potential states. The 2:1 multiplexer translates the four different states into a restored data signal and a reliability signal indicating the decision reliability.

Abstract: A method and an arrangement are disclosed for recovering a clock signal from a data signal. At least a first portion of the data signal is synchronized in a decision circuit with a clock signal from a controlled oscillator. The phase difference between the synchronized signal and at least a second portion of the data signal, which is not fed to the decision circuit, is determined by means of a phase detector and used to control the clock signal of the controlled oscillator, with the synchronized data signal and the portion of the data signal not fed to the decision circuit being applied to the phase detector bit-synchronously.

Abstract: A process for improving the signal quality of optical signals, a transmission system for the transmission of optical signals, and a modulator for DGD are proposed. Transmission system, transmitter and process operate with a DGD- and a polarisation modulator which modulates the optical signal at the transmitter end.

Abstract: A method of improving the signal quality of optical signals and also a transmission system for transmitting optical signals with FEC are proposed. In this connection, transmission system, transmitter and method operate with a polarization modulator that modulates the optical signal at the transmitter end.

Abstract: The invention relates to an optical demultiplexer with at least one input and several outputs, for distributing an optical information input to the outputs. The invention relates, in addition, to an optical multiplexer with several inputs and at least one output, for linking optical information inputs to an information output. The demultiplexer and the multiplexer are of multistage design. The individual stages are connected to one another by means of optical waveguides.

Abstract: An optical receiver for receiving digitally transmitted data, the receiver containing connected a digital filter 2 and a decision circuit 3 to it for detecting the incoming data signals 1, and a clock contact 15, the decision circuit being connected with a computing unit 5 and containing a pseudo-error monitor circuit for detecting bit errors, and parameters of the digital filter 2 and of the decider/pseudo-error monitor circuit 3 being adjustable by the computing unit 5 connected to them.

Abstract: A process for improving the signal quality of optical signals, a transmission system for the transmission of optical signals, and a transmitter for the transmission of optical signals are proposed. Transmission system, transmitter and process operate with a polarization modulator which modulates the optical signal at the transmitter end.

Abstract: In optical transmission systems it is desirable to increase the bit rate of digital signals to, e.g., 40 Gb/s and more. In such systems there is an upper bit-rate limit above which conventional directly modulated lasers and their drive electronics cannot be employed. An optical transmission system is disclosed in whose optical transmitter (1) an electric multilevel signal (V) composed of two electric digital signals (V.sub.1, V.sub.2) modulates a semiconductor laser (4), so that an optical multilevel signal (V) is transmitted. The optical receiver (2) contains a decision circuit (7) which recovers the digital signals (V.sub.1, V.sub.2).

Abstract: If a digital signal is transmitted over a dispersive optical waveguide (3) with an optical transmitter (2) whose output signal is frequency-modulated (here: FSK-modulated) by the digital signal, the two wave trains which occur in FSK modulation arrive at the end of the fiber-optic link at different times (propagation time difference .DELTA..tau.). The electric output signal V of an optical-to-electrical transducer (5) at the receive side is intensity-modulated and passes through three ranges of values. To recover the digital signal therefrom, use is made of a novel circuit (6) whose output assumes a first state when a sample value is in the first range of values, a second state when a sample value is in the second range, and the same state as N bits earlier when a sample value is in the third range.

Abstract: When digital signals are transmitted over optical fibers (3), which have a considerable chromatic dispersion at the wavelength being used, the length of the transmission path is very limited when the digital signal to be transmitted is converted into an optical signal by means of intensity modulation. If frequency modulation (also called FSK=Frequency Shift Keying) is used instead of the intensity modulation, the bridgeable path can be greatly increased, but requires a suitable optical receiver at the receiving end. The invention utilizes a simple optical receiver (4), which is not sensitive to frequency modulation, but to intensity modulation. This is possible, because an intensity variation is created, due to the chromatic dispersion of the optical fiber (3) and the resulting running time differences of signal portions at different wavelengths (.lambda..sub.0, .lambda..sub.

Abstract: In a transmitter including a carrier source an input signal is present which contains the information to be transmitted and is composed of signal components having amplitudes less than a predetermined threshold value or equal to the threshold value and signal components whose amplitudes are less than the threshold value or equal to the threshold value. For the purpose of identification, the two signal components are sampled in different ways, for example at different frequencies and are combined into a modulation signal in such a manner that the two signal components have the same sign. In a receiver, a circuit arrangement is provided which identifies the sign of the partial signals on the basis of their different sampling frequencies, demodulates envelope curves and combines them into an output signal which corresponds to the signal.The transmitter and receiver are advantageously components of an analog optical transmission system.

Abstract: To transmit a frequency-division multiplex signal occupying a broad frequency band, e.g., the 40-440 MHz cable television frequency band, over an optical-fiber transmission link, in the transmitter, the whole frequency band to be transmitted is converted by single-side-band amplitude modulation of a high-frequency carrier f.sub.0 to a higher-frequency band, e.g., 840-1240 MHz, which, referred to its lowest frequency, is less than one octave wide. Second-order intermodulations products, which usually result during electric-to-optical conversion, thus fall into unoccupied frequency ranges. At the receiving end, corresponding demodulation is performed employing either carrier recovery or a locally generated carrier. In a preferred embodiment, the frequency band to be transmitted is converted to the higher frequency band in several subbands.