Abstract: The invention relates to a radiation source unit for supplying shortwave optical radiation, and to a method of assembling such a unit. The radiation source unit comprises a diode laser and a waveguide of a non-linear optical material for converting the diode laser radiation into radiation having a smaller wavelength. The diode laser is provided in a bush having a first end and a second, open end. The second end is adapted to accommodate a first holder in which a lens system is arranged for imaging the exit plane of the diode laser on the entrance plane of the waveguide. At a side of the first holder remote from the diode laser a second holder is secured in which the waveguide is arranged. Said holders are aligned and fixed with respect to each other in such a way that the chief ray of the diode laser beam, the optical axis of the lens system and the axis of the waveguide are in alignment, and that the diode laser beam is focused on the entrance aperture of the waveguide.

Abstract: A voltage control system for powering at least one remote load from a local power supply. A voltage control circuit coupled to the power supply produces a supply voltage which is transmitted to the load and is selectively set to any of a plurality of levels. A comparator at the load supplies back to the voltage control circuit an identification signal of a given type when the supply voltage is below a reference voltage level which can safely be applied to the load. The identification signal causes the voltage control circuit to change the supply voltage to a value which exceeds the reference voltage level but does not subject the load to overvoltage.

Abstract: Disclosed is a record carrier for optically detectable data storage, apparatus for manufacturing such a record carrier and apparatus for recording and/or reproducing information on such a record carrier. The record carrier is provided with periodic track variations whose period corresponds to a frequency for which the power spectrum of the digitally coded information substantially exhibits a zero point. When scanned by a beam of radiation, the periodic track variations produce periodic modulation in the beam of a frequency corresponding to the period of the track variations in order to generate a clock signal of a frequency equal to the bit frequency during recording or reproduction.

Abstract: An integrated optical circuit comprises a first device and a second device, which devices are connected by a polarization convertor. The polarization convertor has one or more curved sections of a waveguide, integrated in the optical circuit. The conversion ratio is determined in part by the radius of curvature of the curved sections.

Abstract: A coder/decoder for samples of speech or other audio signals with bit rate reduction includes an adaptive prediction filter having filter coefficients which are recursively computed according to the known Levinson-Durbin Recursion. Such computation is based on reflection coefficients derived from correlation coefficients applicable to segments of the audio signal samples, the reflection and prediction coefficients being in N-bit fixed point arithmetic. A k.sup.th reflection coefficient after its first computation is buffered with a minimum accuracy of N+1 bits, and the k-1 previously computed prediction coefficients are recomputed with a limitation of N bits. If overflow occurs, the buffered value is divided, e.g. by 2, after the re-computation is completed and then rounded to N bits. Since rounding occurs only after the new prediction coefficients are derived, the recursion achieves reduced error and is simpler to calculate.

Abstract: Integrated circuits running with high frequencies are a potential source for RFI (Radio Frequency Interference). To reduce RFI, on-chip dedoupling capacitors are included in the design. To gain maximum advantage of these decoupling capacitors, they should be placed close to drivers and flip-flops. In a standard cell design approach for fabrication of the ICs, capacitors are embedded below the power supply lines. These capacitors are put in special cells, called cap-cells, which are placed by the place and route software on either side of each row of standard cells. Thin oxide capacitors are preferred because they offer the largest capacitance per area. In addition, first and second metal above the capacitor are increased to form thick oxide capacitors that give additional capacitance.

Abstract: In a sychronizing arrangement for synchronizing two streams of optical pulses, the problem arises that for pulse frequencies above 10 GHz the operation of the synchronizing arrangement becomes increasingly difficult. To overcome that problem it has been proposed to use a phase locked loop having an optical phase detector, but prior art optical phase detectors have low efficiency and was rather complex. According to the invention an optically controlled optical switch is used as the phase detector.

Abstract: An optical communication system includes a directly modulated semiconductor laser (10), the output of which results in pulse shortening of light pulses corresponding to high level bits of a high frequency electrical digital modulating signal. A travelling wave laser amplifier (14) coupled to the laser provides an amplified modulated light signal to an optical channel (16), and an optical detector (18) converts a light signal received from the optical channel into an electrical signal. The amplifier has an overshoot characteristic which provides an extended output when overdriven by a high level optical input pulse, and the modulated laser is arranged to provide such high level pulses. The overshoot characteristic of the amplifier thus compensates for pulse shortening produced by the modulated laser in the case of isolated high level bits and the initial bit of a stream of high level bits. The invention also relates to a transmitter and to a repeater for use in such an optical communication system.

Abstract: The electronic card comprises an electrically insulating card support provided with a cavity for accommodating an integrated circuit and, on one surface, with metal contact pads which are electrically connected to contacts of the integrated circuit. The invention comprises the steps of: (i) the application by an MID technique (Moulded Interconnection Devices) of electrical conductor tracks, all arranged on the bottom and the lateral walls of the cavity, and each connected to one of the metal contact pads arranged on the surface of the support which comprises the cavity, (ii) the realization of electrical connections connecting the contacts of the integrated circuit arranged in the cavity to the conductor tracks on the bottom of the cavity, and (iii) filling up of the cavity with a protective resin which is subsequently polymerized.

Abstract: Echo cancellation in a full duplex loudspeaking telephone is usually effected by means of an adaptive filter, which by means of a combining (difference) circuit cancels the microphone-signal component picked up by the microphone via the acoustic echo path. For a correct operation of the adaptive filter the levels between the signals at the input line and at the input of the combining circuit should be in a given ratio. For automatically adjusting this ratio an attenuator circuit (26) is arranged before the combining circuit, and at the output of the combining circuit an amplifier (22) is added whose gain is inverse to the attenuation of the attenuator circuit. A control circuit (40) compares the levels of the signals at the input line (10) and at the input of the combining circuit and adjusts the attenuation of the attenuator circuit and the gain of the amplifier accordingly.

Abstract: An optical component (7) is described in which the frequency of electromagnetic radiation is raised and which comprises a non-linear optical medium and an optical modulation structure (21) so as to compensate for the wavelength dispersion in the non-linear optical material so that there is phase matching. By providing a satellite layer (15) having a high refractive index proximate to the modulation structure (21), the wavelength at which phase matching occurs is not critical for the layer thickness of the non-linear optical medium. An opto-electronic device (1) for raising the frequency of electromagnetic radiation, comprising such a component (7) as a frequency-raising element is also described.

Abstract: A square-law detector which provides a square-law relationship between the amplitude of the input signal and the amplitude of the output signal, and having a frequency transfer characteristic which is a continuous function consisting of a rising portion up to a predetermined frequency followed by a falling portion following the predetermined frequency. Thus the frequency characteristic is generally triangular, which is advantageous in that the output signal as function of frequency has a much more uniform, i.e. trapezoidal, pattern than is obtained with a conventional detector having a substantially rectangular frequency transfer characteristic. This is especially important when the detector is used in a receiver for FSK modulated signals having a large frequency deviation, since the modulated signal spectrum then has two relatively discrete power peaks.

Abstract: A power supply device includes a series arrangement of an inductance (3), a switching device (4) clocked by a control circuit (12), and a current measuring impedance (5), which series arrangement is arranged between two terminals (1, 2) to which a supply voltage (Ue) can be applied. A voltage (Um) appearing across the current measuring impedance (5) is applied via an input resistor 17to an input (18) of the control circuit (12) to control the switching device (4), a capacitance (19) being in parallel with the input (18) of the control circuit (12).A diode (20) is arranged in parallel with the input resistor (17), dimensioned in such a manner relative to one another that the diode (20) becomes conductive only when the Voltage (Um) across the current measuring impedance (5) exceeds a given limit value. Also, the ohmic resistance of the diode (20) together with the capacitance (19) forms a smaller time constant than the input resistor (17) with the capacitance (19).

Abstract: Telecommunication systems such as PON-FITL-Systems are known having a TDMA frame structure and comprising a main station and a number of substations. The known systems can comprise apparatus for coarse ranging and for fine ranging. A Pseudo Noise Sequence based coarse ranging technique employs coarse ranging at a fixed position within the upstream multiframe reserved for ranging, preferably for fine ranging. By applying a low power Pseudo Noise Sequence for coarse ranging and sampling the range in the main station only within a fine ranging window the position of which is known to the main station, a more accurate coarse ranging is achieved. Within the fine ranging window normally no data are present, and thus the signal-to-interference ratio is an order of magnitude better than in the other part of the frame.

Abstract: A CDMA transmission system wherein a data sequence which is to be transmitted is frequency band spread by multiplying the data words therein by selected code words. In order to minimize the necessary bandwidth, a frame structure is established and the spread spectrum data words are compressed into data bursts each of which is included in one or more time slots of a data frame. Within a frame a data burst is located at a particular time delay t.sub.0 following commencement of the frame and has a duration t.sub.d corresponding to the bit rate of the data burst.

Abstract: Uniform electrically conducting multicomponent material is deposited on an electrically conducting substrate by means of a PCVD method. A plasm, for example a glow discharge plasm, a high frequency plasm or a microwave plasm is generated in a reaction space. The plasma is periodically reciprocated. Starting materials for the single components of the multicomponent material are added to a flowing gas phase. To obtain multicomponent material of the desired composition, the flowing gas phase is split into at least two flowing gas phases each comprising only starting materials for a single component of the multicomponent material. The separate gas phases are time sequentially applied to the plasma. The deposited multicomponent material my be subjected to a thermal treatment.

Abstract: Disclosure is given of a device and method for recording by means of a radiation beam user information on a record carrier. The user information is written in the form of optically detectable marks in concentric tracks. The tracks are subdivided into sectors. The record carrier used has ring-shaped zones. Within these zones lie the sectors aligned seen in radial direction. For writing the marks in the tracks, a write intensity of the radiation beam is set to a determined set value. For this purpose, a test information pattern is written in a buffer sector which is situated on an edge of a zone. Then the test information pattern is read back during which operation the test information pattern is converted to a corresponding test data pattern. Based upon the test data pattern a set value for the write intensity is determined.

Abstract: Optical isolator, circulator, switch or the like, including a Faraday rotator to which a magnetic field is applied which is oriented along the direction of propagation of light and which is arranged between a preceding polarization filter and a succeeding polarization filter whose planes of polarization enclose an angle with respect to each other such that light can only traverse in one direction, the Faraday rotator having different propagation constants .beta..sub.TE and .beta..sub.TM in a TE plane and a TM plane, respectively. The elaborate technique for adapting the propagation constants of the TE wave and the TM wave is mitigated in that the TE plane of the Faraday rotator is aligned in such a way that it extends between the planes of polarization of the polarization filters.

Abstract: A transmission system having a polarization-sensitive receiver which includes polarization adaptor for changing the state of polarization of a received signal until it corresponds to an optimum polarization. For determining the direction in which the polarization should be adjusted, local signal generators produce polarization variations which influence the output signal of the polarization adaptor and the change in the signal is detected. In order to prevent slow variations in the received signal from affecting the polarization detection, a band-pass filter is included to suppress such variations.

Abstract: In a multiple access network the signals transmitted by a plurality of sub-stations to a main station over a common channel must be distinguished for each sub-station. A method of achieving this is to employ SCMA (Subcarrier Multiple Access), according to which in each sub-station the transmit signal is modulated on a subcarrier having a different frequency for each substation, and the modulated subcarrier amplitude modulates a main carrier which has substantially the same frequency for all sub-stations. To minimize mutual interference between sub-stations, according to the invention the amplitude of the main carrier transmitted by a sub-station is reduced during intervals in which the modulated auxiliary signal from that sub-station is not present or is at a zero reference level. In this way the number of modulated carrier signals which are present at any given time is reduced. Mutual interference is thereby significantly reduced, because it depends on the squared number of carriers present in the system.