Abstract: In a filter in which, in order to obtain the desired filter characteristic, a weighted sum of different signals is formed, it is proposed in accordance with the invention that for the formation of said sum means are employed which are constituted by capacitor circuits, which during a first time interval are each charged by said signals, and by a connection circuit for the formation, during a second time interval, of the equivalent of a single capacitor across whose plates the weighted-sum signal appears.The invention is used for the filtration of sampled analog signals.

Abstract: A circuit for rapidly resynchronizing a clock with an external clock is disclosed. The clock to be synchronized is obtained at the output of a phase-locked loop by dividing the frequency of a reference clock in a frequency divider whose division factor is controlled by a phase controller which detects the deviation between the transitions of the two clocks to be synchronized. According to the invention, the pulses of the reference clock are applied to the phase-locked loop by means of a gate, with this gate being rendered nonconductive by means of the characteristic transition of the clock to be synchronized which follows the appearance of a resynchronizing control signal, and thereafter this gate is rendered conductive by means of a characteristic transition of the external clock.

Abstract: To supervise the operation of an arithmetic unit of a digital transmultiplexer intended to convert a TDM-signal into a FDM-signal and vice versa, a pilot signal is utilized as the test signal which pilot signal is also used to control the level of the received FDM-signals and is processed in the transmultiplexer. The pilot signal selection filter used for controlling the level is used, also in time-division multiplex, for selecting a component having a frequency equal to the pilot signal frequency and occurring in each of the two input and output signals of the arithmetic unit.

Abstract: A balancing amplifier comprising a pair of transistors arranged as a differential amplifier and a negative feedback network including a transistor voltage follower as a part of the load circuit of each transistor of the pair of transistors. Owing to the negative feedback network high level signals can be balanced. The amplifier provides output signals in phase opposition from a single-ended input signal.

Abstract: A circuit for the synchronization of the operating cycles of a digital arrangement with an external clock signal which arrangement includes a calculating unit and a circulating store which must produce a sequence of coefficients in a predetermined order at each cycle. The circuit has switching means for circulating the coefficients in the store either in series or word-by-word, means for producing a word clock, means for forming operating cycles synchronous with the word clock and for starting each operating cycle at each characteristic transition of the external clock signal appearing after the end of each cycle. The switching means are controlled to have the sequence of coefficients circulate in series once in each cycle and for having the coefficients circulate word-by-word for the remaining period of time.

Abstract: A device for processing a signal coded by means of delta modulation with a sampling rate F, comprises an analyzer for the delta modulation signal for successively forming data each of which characterizes the number of binary elements of two successive trains formed by different binary elements, each train comprising a binary element or a series of identical binary elements, a store in which said data are entered, and, finally, means for forming from the data entered into the store a sequence of binary elements composed of .lambda. times the two above-mentioned trains with a frequency of the binary elements equal to 2.lambda.F, .lambda. being an integer exceeding one. The device supplies a digital signal, which, after decoding, constitutes an excellent approximation of the analog signal which had been coded.

Abstract: Subscriber's circuit for connecting a subscriber's line to a telephone exchange, comprising a symmetrical amplifier which is arranged between two feed points having different potentials, the amplifier circuit having two input terminals and two output terminals, each one of the output terminals being connected to a wire of the subscriber's line and each input terminal of the symmetrical amplifier circuit being connected to an output of an associated digital-to-analog converter an input of which is connected to the one or to the other feed point by means of a change-over switch, the change-over switches being controlled in phase opposition by a binary digital signal which characterizes a voltage desired for the subscriber's line and which is derived from a digital signal generator under the control of the telephone exchange.

Abstract: A radio range measuring apparatus having a controlled modulation slope in order to keep the beat frequency between the transmitted signal and the received signal constant. The apparatus also measures the speed at which a mobile target approaches or recedes by means of a generator of a fixed frequency which, after frequency division, maintains the duration between the start of two consecutive sawtooth modulation signals fixed. A particular spectral line of the beat signal is demodulated by this fixed frequency via a mixer whose output is filtered by a passband filter. The signal at the output of the filter has a frequency which is equal to the Doppler frequency, proportional to the speed.

Abstract: A receiver of a system for data transmission by means of p-phase modulation comprises a digital phase discriminator with a calculating unit which calculates in a first interval of each sampling period the in-phase and quadrature components of a signal derived from a passband signal at sampling instant jT by a phase rotation over an angle equal and opposite to the phase of a reference carrier at instant (j-1)T.A simple derangement detector is obtained by means of a sign detector for a component supplied by the calculating unit during a second interval of each sampling period, the phase of the reference carrier then having been subjected to a phase rotation equal to the phase variation of the transmitted carrier, and by means of a calculated circuit which calculates the quantity .vertline.x.sub.3 .vertline.-kx.sub.3, where k<tan (.pi./p) and x.sub.3, x.sub.

Abstract: The disclosed system is intended to supply angular and range data regarding the position of an object to be located in a reference system. The system comprises an interrogator which transmits a linearly frequency-modulated signal to a transponder disposed on the object. The transponder is provided with means for shifting the frequency of the received signal in one direction by a predetermined amount characteristic of that transponder and means for retransmitting the received signal. The interrogator further includes a pair of receiving antennas whose signals are used for forming beat signals with the transmitted signal. The interrogator is also provided with means for shifting the frequency of the beat signals in the other direction by the same amount. At least one of the shifted beat signals is applied to a frequency discriminator whose output signal is utilized for controlling the slope of the modulation signal in order to keep the frequency of the shifted beat signal constant.

Abstract: A ground proximity warning system used by aircraft when unsafe flight configurations defined by specified flight warning mode envelopes are detected. The invention provides that alarm generation signals are not immediately given, but instead the continuing flight of the aircraft is monitored by an alarm filtering system. The filtering system uses independently variable maximum and minimum threshold levels, and filtering constants which can be incremented and or decremented as functions of the flight location of the aircraft and the specific warning mode envelope for suppressing false or unnecessary alarm generation. The filtering parameters may be varied independently for each flight warning mode. In addition, a priority-ordered series of audio warnings are provided so that warnings once started are completed in the absence of higher priority warnings, even if the warning conditions cease to exist.

Abstract: A range measuring apparatus of the linear frequency modulation type is disclosed which comprises a measuring control loop for rendering the beat frequency between the transmitted and received frequencies equal to a fixed frequency. The apparatus further includes means for forming a permanent second beat signal between two signals derived from the generator supplying the frequency modulated signal, one of these signals being delayed by means of the delay line. A phase detector receives this second pulsed signal and the signal of a controlled frequency oscillator and supplies a signal which controls the slope of the frequency modulation. The error signal of the measuring control loop controls the frequency of the signal from the oscillator. This arrangement results in an increased precision in the range measurements.

Abstract: A circuit for converting into an FDM format spatially separated signalling signals and pilot signals, comprises a digital filter bank for converting the signals into the FDM format. A receiver for separating the signalling signals and pilot signals from the FDM signal comprises another digital filter bank for producing baseband signals. These filter banks have a transfer characteristic formed by a number of passband curves which are derived from the characteristic of a selected low-pass filter.

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.