Telecommunications Radioelectriques Et Telephoniques T.r.t.

Telecommunications Radioelectriques Et Telephoniques

Jacques Lucien Daguet

Maurice Georges Bellanger

System for digitally converting baseband channel signals into a frequency-division multiplex signal. The system comprises at its input converter circuits by each of which the sequence of codewords of the digital signal which correspond to each signal to be converted is divided into two interlaced sequences. The two devices required for processing each of the two digital signals supplied by the input circuits in the form of converters are combined so as to use in cascade a Fourier transformation device, a set of arithmetic units in the form of digital filters and a time-division multiplexer which supplies the desired multiplex signal. Use: multiplex transmission of speech signals.

System for digitally converting baseband channel signals into a

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.

System for data transmission through the channels of a frequency

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.

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St. Maur des Fosses, France

Jacques Lucien Daguet