Abstract: A digital subscriber line transmission system using QAM modulation on several equally spaced discrete tones, uses, at a high transmission rate, N=2048/p or 4096/p tones spaced by 4.3125p KHz, where p is a power of 2.

Abstract: A digital signal processing system, including an analog-to-digital converter adapted to provide at least n-bit samples to a processor, and range selection circuitry for stepwise adjusting the range of the analog-to-digital converter to the amplitude of an input signal and for shifting the position of the n-bit samples on the processor bus according to the selected range.

Abstract: A digital signal processing system, including an analog-to-digital converter adapted to provide at least n-bit samples to a processor, and range selection circuitry for stepwise adjusting the range of the analog-to-digital converter to the amplitude of an input signal and for shifting the position of the n-bit samples on the processor bus according to the selected range.

Abstract: A digital signal processing system, including an analog-to-digital converter adapted to provide at least n-bit samples to a processor, and range selection circuitry for stepwise adjusting the range of the analog-to-digital converter to the amplitude of an input signal and for shifting the position of the n-bit samples on the processor bus according to the selected range.

Abstract: The present invention relates to a method for setup of a signal in multicarrier modulation, including clipping the signal, in amplitude, with respect to a threshold value, and of reinjecting, with a delay and on the signal to be set up, a clipping noise redistributed, at least partly, outside the useful slip of the signal in multicarrier modulation.

Abstract: The present invention relates to a method for setup of a signal in multicarrier modulation, including clipping the signal, in amplitude, with respect to a threshold value, and of reinjecting, with a delay and on the signal to be set up, a clipping noise redistributed, at least partly, outside the useful slip of the signal in multicarrier modulation.

Abstract: The system includes two transmitters (T1, T2) and two receivers (R1, R2). One transmitter (T1) may include a wavelength tunable laser, sending an FSK optical signal (OS1) which has a constant intensity. In a first receiver (R1) this FSK optical signal (OS1) is transformed into an IM signal (OS1') by an optical pass band filter. This IM signal (OS1') is then detected by a first direct detection receiver (DM). In a second direct detection receiver (R2) the FSK optical signal (OS1) is not detected, since it has constant intensity. A second transmitter (T2) includes a Fabry Perot laser or a LED with a broad linewidth, sending an IM optical signal (OS2). This IM optical signal (OS2) is detected by the second direct detection receiver (R2). It is not detected by the first direct detection receiver (DM), because it is strongly attenuated when passing through the narrow bandpass optical filter (TM) before being applied to the first direct detection receiver.

Abstract: A communication system includes a main station (MS) and a plurality of substations (SX/SZ) which include each a transceiver and are all connected in parallel to first (UL) and second (DL) unidirectional links on which recurrent first and second cells of fixed length are transmitted in opposite direction. Each of these cells contains a plurality of signalling channels smaller than the number of substations. When a substation has to transmit data it starts an allocation procedure wherein the substation cooperates with the main station and by which a channel is allocated to it. Afterwards prior to transmitting the data the substation transmits a request signal in the allocated channel and starts transmission after having received from the main station a grant signal in the homologous signalling channel of a second cell. De-allocation of a channel occurs as soon as the latter is no longer needed.

Abstract: To determine the equalisation delay of a substation (S3), the main station (C) of a transmission system measures, during an initial coarse measurement, the time interval between the sending of a first ranging signal to the substation and the receipt of a reply signal. This reply signal has a frequency and amplitude substantially lower than the information signals sent by other substations (S1, S2) of the system to avoid interference therewith. During a subsequent fine measurement the main station measures the time interval between the sending of a second ranging signal and the receipt of a second reply signal having the same characteristics as the information signals. The other substations have to stop transmission of signals during an interval equal to the uncertainty time interval with which the equalisation delay was measured during the coarse measurement.

Abstract: Optical transceiver arrangement to transmit information signals (S1, . , Sn) from a transmitter arrangement (T) to a receiver arrangement (R) over an optical waveguide (L). This is achieved by modulating electrical subcarrier waveforms with these information signals (S1, . , Sn) using modulation means (M1, . , Mn), converting them to optical signals using electrical/optical convertors (E/01, . , E/01n), and by transmitting these optical signals, by means of time division multiplexing means (TDM1, . , TDMn), in different time slots if the subcarrier waveforms have the same frequency. The modulation- and time division multiplexing means are controlled by corresponding individual control modules (C1, . , Cn) under control of a central control module (CC) included in the receiver arrangement.

Abstract: A protection arrangement protects an optical transmitter device with n optical transmit circuits or an optical receiver device with n optical receive circuits. It includes fault evaluating circuitry to detect a defective transmit/receive circuit, a spare transmit/receive circuit, and switching circuitry. Upon detection of a defective transmit/receive circuit by the fault evaluating circuitry, the fault evaluation circuitry controls the spare transmit/receive circuit and the switching circuitry to bypass the defective transmit/receive circuit with the spare transmit/receive circuit.