Abstract: A communications system includes a primary station having transmitting and receiving sections, a formatting stage for formatting messages to be transmitted by the transmitting section, and one or more secondary stations. The or each secondary station has a receiving section for receiving messages from the primary station and a transmitting section for transmitting signals as pseudo-random code sequence signals, and the primary station is adapted to receive and to simultaneously decode and detect the or each of the pseudo-random code sequence signals. The simultaneously decoding and detection operations involves implementation of a Fast Fourier Transform (FFT) in a manner that a code sequence for despreading the pseudo-random code sequence is applied within the FFT. A resulting spectrum is checked for a peak which indicates that one of the pseudo-random code sequences has been successfully decoded and detected.

Abstract: A method of transmitting messages in a communication system including a primary station and at least one secondary station, the secondary station being identifiable by an address code word, the primary station transmitting messages signals in the format of the address code word of an addressed secondary station concatenated with a plurality of message code words, wherein the primary station indicates the provision of an optional facility which it can provide to a secondary station by transmitting indicia representative of the facility in a field contained in at least one of the message code words concatenated with the secondary station's address code word.

Abstract: A digital signal converting method and device for converting an input image rate into an output image rate, is applied to input images which are formed by a plurality of input data frames. The method storing the input frames, calculating a sliding average over a plurality of stored frames, and deriving the averages for producing output images with a timing fixed by the output image rate.

Abstract: A series of autostereograms of a three dimensional scene is displayed. The apparent depth of a reference surface in the scene is varied from one autostereogram of the series to another. A human viewer looks at the autostereograms, adjusting the eyes to viewing of a surface at an arbitrary depth. When the apparent depth of the surface corresponds to the arbitrary depth, the human viewer will perceive a three dimensional effect and signal this with a feedback signal. Upon detection of the feedback signal a further autostereogram is displayed instead of the series of autostereograms. The further autostereogram displays of a further three dimensional scene containing a further reference surface, in which a further apparent depth of the further reference surface is selected according to the apparent depth for which the viewer feedback was received. Thus the further apparent depth is adjusted to the setting of the eyes of the human viewer.

Abstract: The present invention relates to a power supply circuit SC receiving a power supply current IS at an input voltage VLN and intended to supply a voltage VDD, comprisinga capacitance CS,a first transistor T1 enabling the capacitance CS to be charged by means of the power supply current IS,a second transistor T2 enabling said charge to be interrupted by diverting the power supply current IS to the reference terminal VSS, anda control module T3, T4 controlling the conductance of the first and second transistors T1 and T2 as a function of the values of the input and output voltages VLN and VDD.According to the invention, the power supply circuit SC also comprises a measuring module with which the value of the power supply current IS can be controlled.

Abstract: A message transmission system, such as a paging system, provides message compression through the use of corresponding memories or memory areas in a primary station and a secondary station storing identically the most frequently used n items of numeric only or alpha-numeric data. The contents of the memories are updated dynamically to reflect changes in the most frequently used items by the primary station examining messages to be sent to a particular secondary station to see if an item is being used more frequently than one of those stored, in which case the primary station initiates a reprogramming message which is sent to the secondary station. In response to receipt of the reprogramming message, the particular secondary station updates its memory and acknowledges to the primary station that it has done so, and upon receipt of the acknowledgement, the primary station correspondingly updates its memory.

Abstract: Circuit arrangement for generating a control signal. A circuit arrangement for generating a control signal for a controllable oscillator of a receiving device, is arranged to mix an FSK modulated input signal, having at least two predetermined input frequencies, with an oscillation, output by a controllable oscillator, so as to form an intermediate frequency signal, as well as to derive from the intermediate frequency signal a data signal whose instantaneous value is determined by the frequency of the intermediate frequency signal (intermediate frequency) and also a demodulator pulse signal whose frequency and/or phase is a measure of the frequency and/or phase of the intermediate frequency signal, from the intermediate frequency signal.

Abstract: A receiver has a crystal oscillator (10) whose frequency can be adjusted in response to temperature compensation (TC) and automatic frequency control (afc) signals. The TC and afc signals are summed and applied to an op-amp (70) having a fixed gain functioning as a current to voltage converter. An output of the op-amp (70) is applied to the crystal oscillator (10). If the receiver is switched--on and--off in accordance with say a time division protocol, the output of the op-amp (70) is applied by way of a switch (72) to a storage circuit (30,C) which when the switch is open applies a bias voltage on the crystal oscillator (10) to maintain its output frequency.

Abstract: In a speech communication network in which a transmitter (1) transmits speech signals via a network (4) to a receiver (8), it can happen that more traffic is offered to the network (4) than it can handle. In order to reduce the network load, at least one node (24) is arranged to perform bitrate reduction to delete some of the prediction parameters representing the speech signal. It can also be the case that a receiver comprises a speech decoder having insufficient computational power available for decoding the encoded speech signal. In such case, the speech decoder is arranged for using only a part of the prediction parameters available. This results in a lower complexity of the synthesis filter (60).

Abstract: An electronic apparatus such as a digital wide area pager has a receiver IC (10) capable of operating directly from a single cell battery (24) for as long as the terminal voltage (V.sub.BAT) is above a specified minimum voltage. Other ICs (14, 16) of the pager operate at a higher voltage supplied by a multiplier (26) connected to the battery (24). The multiplier (26) is able to operate at values of V.sub.BAT below the specified minimum voltage. A control circuit (34) determines when the terminal voltage (V.sub.BAT) decays below the specified minimum voltage and supplies the receiver IC (10) with a stepped-down voltage from the multiplier (26) to ensure its sensitivity remains acceptable.

Abstract: Known is a two stage high frequency amplifier preceded by a large amplification gain stage providing a fixed swing signal for the two stage amplifier. Particularly in portable devices such as pagers, and mobile or cordless phones, such a receiver structure consumes much power. An amplifier structure is proposed with a cascade of at least four amplifier stages, alternately resistive feedback amplifier stages and non-resistive amplifier stages. Herewith, a dramatic improvement of the gain-bandwidth product is achieved, for the same static power consumption. The amplifier can be used in a PLL of a synthesizer circuit for a pager, cellular or cordless phone, or any other suitable communication device.

Abstract: A message transmission system includes at least one primary station arranged for making transmissions on a down-link and a plurality of secondary stations arranged for making transmissions on an up-link, each of the secondary stations having its own address which is transmitted as part of the down-link message. Each of the secondary stations is configured for generating responses to messages as pseudo-random data sequences, the pseudo-random data sequence being generated by a secondary station at any one time being dependent on at least the address assigned to the secondary station and/or information contained in the message.

Abstract: A radio pager device includes a display having a zoomed-out multiline mode and a zoomed-in single line mode for display of at least a portion of a series of characters at a time extracted from a message having an address or identification code which is among those from which the pager is authorized to extract message data. The zoom mode is selectable on either a system basis, by default, or a message basis. The message specific zoom mode is determined by accessing display per address information stored in volatile memory and programmable by the user. In the single line mode, continuous horizontal character by character scrolling may be selected by the user and controlled by key actuation to toggle between a stationary paused state and a continuously scrolling state.

Abstract: In a CELP coder a comparison between a target signal and a plurality of synthetic signals is made. The synthetic signal is derived by filtering a plurality of excitation sequences by a synthesis filter having parameters derived from the target signal. The excitation signal which results in a minimum error between the target signal and the synthetic signal is selected. In order to reduce the complexity of the search for the best excitation signal, thee selection is done in two stages. First a preselection of a small number of excitation sequences is made using a reduced complexity synthesis filter. Thereafter, with this small number of excitation sequences, a full complexity search is made. Due to the reduced number of excitation sequences involved in the final selection the required computational complexity is reduced.

Abstract: An image-guided surgery system includes an alignment device (1) which measures the direction of a target position (2) with respect to a starting position (4). Subsequently, the alignment device (1) places one end of the surgical instrument (3) in the starting position and rotates the surgical instrument in such a manner that it is oriented along the measured direction. It is ensured that the end meanwhile remains in the starting position. The image-guided surgery system includes a system of arms (7), one end of which is provided with an alignment member (5) for supporting the surgical instrument. The alignment member is preferably a sphere provided with an opening (6) in which the surgical instrument fits.

Abstract: In a transmission system a sequence of digital symbols including concatenated words, is transmitted by a transmitter (2) via a transmission medium (14) to a receiver (16). In order to reduce the transmission capacity no word synchronizing symbols are introduced in the sequence of digital symbols. In order to achieve word synchronization, a synchronization processor estimates the probability function of one single predetermined string as function of the position of the string in the sequence. The correct position of the words is derived from this probability function.

Abstract: A communications receiver such as an integrated zero IF receiver comprises an input for receiving an input signal and a zero IF frequency down conversion circuit coupled said input and constructed to provide quadrature related signals (I,Q) at a substantially zero intermediate frequency. In order to balance the signal paths, at least one capacitance in each of the quadrature related zero IF signal paths of the frequency down conversion circuit comprises at least two integrated capacitors connected in anti-parallel. By fabricating the integrated capacitances in this way the symmetry of the circuit is maintained which enhances significantly the second-order inter-modulation performance.

Abstract: An M-ary FSK receiver in which a frequency down-converted signal is treated as an M-ary DPSK signal with symbol repetition coding. The output of a frequency demodulator (20) is integrated (22) over an optimally chosen time interval which is a fraction of the symbol interval to obtain N phase change estimates per symbol. These N sub-symbols are manipulated (24, 26) to obtain corresponding soft decisions which are then summed (32, 34) over a symbol period (or a substantial fraction thereof) to provide an overall soft decision for each bit comprising an M-ary symbol. These outputs may be used directly as soft decisions for forward error correction or applied to a threshold circuit to obtain hard decisions.

Abstract: A telecommunication station having the capability to both block selected incoming calls and transfer other selected incoming calls. The station further has the capability to provide user messages to the blocked calls and thereafter, if desired, further divert the blocked calls to another selected station.

Abstract: A telephony device includes a rectifier bridge (GB) intended to be connected to a telephone line and to supply a rectified line current, an interface module (INT) permitting the transmission of signals in the direction of the telephone line and supplying an information signal (Iin), and an amplifier (AGC) whose gain is proportional to the value of a control current (Icnt) supplied by a control module (CNT). The control current (Icnt) is proportional to an exponential of a linear equation of the inverse of the value of the information signal (Iin) in order to compensate for the attenuation which the signal has undergone during its transport through the telephone line.