Abstract: Digital transversal filter for realizing a lowpass filter with a cut-off frequency f.sub.g and an impulse response h.sub.1 (i), a lowpass filter having a cut-off frequency 2f.sub.g which has a transfer characteristic which is in phase with the first-mentioned lowpass filter, as well as a lowpass filter with a quadrature transfer characteristic of the in-phase filter.

Abstract: This transition detector is intended to supply pulses which characterize the instants the signal passes a threshold. This signal, which appears in a rectangular form is applied to a first integrator which supplies a signal which increases or decreases in accordance with the sense of the rectangular signal and to a branch which comprises a series arrangement of a delay circuit and a second integrator which is identical to the first. The outputs of the two integrators are connected to a comparator which supplies the desired pulses. At least at the start, the output of the first integrator is entered in a store at a given instant and at an instant which is so much later as the delay supplied by the delay circuit the second integrator is forced to assume the value stored in the store.

Abstract: A device for connecting optical fibers, the ends of which are provided with cylindrical envelopes of magnetic material which envelop the ends of the fibers and which are rigidly connected thereto. The connection device comprises a magnet having pole-shoes provided with means for guiding the said envelopes in order to position the end faces of the fibers one opposite the other in the air gap formed by the pole-shoes.

Abstract: An arrangement for computing the discrete Fourier transform intended for converting N samples of a real signal in the time domain to N real Fourier coefficients. This device is implemented with a conventional Fourier transformer of the order N/4, to which an input computer unit and an output computer unit are connected in which a small number of multiplications of complex numbers is performed.

Abstract: Passband equalizer in a system for data transmission by means of phase modulation. The equalizer comprises two filters in quadrature with adjustable coefficients. Difference circuits connected to the equalizer output form difference signals between the two quadrature components of the equalizer output signal and the two components of an estimated signal which is especially formed from phase jumps associated with the transmitted data signal. A pair of difference circuits is associated with each pair of corresponding coefficients of the two filters and forms difference signals from both components of the passband signals available in the two filters in places corresponding with the said pair of coefficients. The changes in the coefficients are calculated from the above said difference signals.

Abstract: Parallel data transmission system in which the data signals are converted to multilevel digital signals and transmitted through the channels of a frequency division multiplex system. To compensate for the delays between the data signals received in the various channels of the multiplex, a pilot signal is transmitted in each channel in the form of a signal which only has a real component. At the receiver side a filter circuit is used which comprises a first fixed coefficient part at whose input the data signal is multiplied by a component of the received pilot signal and a second part having two variable coefficients which are derived from the two components of the received pilot signal.

Abstract: Frequency demodulator for a frequency-shift-keying data transmission system, which demodulator comprises, in cascade, a monostable circuit, a lowpass filter and a voltage comparator to which a threshold voltage is applied. The demodulator further comprises a switch which is operated by the monostable circuit and supplies to the lowpass filter either one or the other of two voltages derived from the same supply source and having different polarities. The threshold voltage is fixed at zero and in order to correct the bias distortion one of the said two voltages is adjusted.

Abstract: The subject matter of this application concerns directional slot antenna suitable for very high frequencies. The antenna is made up from a wave guide closed at one end on a terminal absorption load. One face of the wave guide is characterized by an elongated slot of consistent width which is formed in relation to the remainder of the wave guide according to a prescribed mathematical relationship.

Abstract: An arrangement for digitally processing a given number of analog channel signals, more particularly a digital multiplexer and demultiplexer provided with a number of signal paths each comprising a recursive digital filter and delay circuits arranged in cascade therewith, said filter circuits having an amplitude-frequency characteristic of a lowpass filter having a cut-off frequency which is equal to half the bandwidth of a channel signal and a phase-frequency characteristic which is such that the difference between such a phase-frequency characteristic and the phase-frequency characteristic of a reference digital filter has a sawtooth-shaped variation, the slope of the sawtooth being opposite to the slope of the cooperating delay circuit. The arrangement furthermore comprises in cascade a discrete Fourier transformer connected to the signal paths.

Abstract: An arrangement for simultaneously producing signals having a decreasing frequency and signals having an increasing frequency. In this arrangement the signals have frequencies which are complementary relative to the double value of a central frequency. The arrangement includes a pair of voltage-controlled oscillators controlled by signals supplied by a control generator. The arrangement is characterized in that for each oscillator there is provided with a phase control loop and that the control generator is of the digital type designed to supply two pairs of digital signals. One pair is applied to the frequency dividers and the other is applied to the oscillators so as to tune them to such a frequency that they are in the operating range of the phase control loop.Use: Radio-electric transmission of data.

Abstract: A speech transmission system employing a semi-vocoder comprising a spectral analyzer and a spectral synthesizer for the upper frequency range of the speech signal. The speech signal in the low frequency range base band is transmitted by using delta modulation and the delta-modulated base band signal is used directly in the receiver as a voice excitation signal for the spectral synthesizer.