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    1.
    发明专利
    未知

    公开(公告)号：DE2718087A1

    公开(公告)日：1977-11-10

    申请号：DE2718087

    申请日：1977-04-22

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： DOGLIOTTI RENATO ,  MAZZEI UMBERTO ,  MENGALI UMBERTO

    IPC: H04L27/06 ,  H04L25/49

    Abstract: A digital demodulator of data signals transmitted by linear amplitude modulation of a carrier, sampled under the control of clock pulses CK1, comprises an interpolating unit UIN including a tapped delay line TDL whose outputs carry, at a given instant, respective signal samples received during different clock cycles. These signal samples are fed to a transversal filter FIN also receiving two sets of interpolation coefficients ak, bk read out from respective memory sections ME1, ME2. The signal samples from the several delay-line taps are multiplied in filter FIN by the two sets of coefficients ak and bk, under the control of a pulse train CK2 and another pulse train CK3 of the same cadence but phase-shifted with reference to the former, and the two sets of resulting products are respectively summed in a digital adder SM and alternately read out to a phase corrector CJ recovering the phase coherence of the demodulated baseband signal.

    7.
    发明专利
    未知

    公开(公告)号：DE2611778A1

    公开(公告)日：1976-09-30

    申请号：DE2611778

    申请日：1976-03-19

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： DOGLIOTTI RENATO ,  MAZZEI UMBERTO

    IPC: H04L27/38 ,  H04L27/00

    Abstract: In a phase-shift-keying (PSK) signaling system with or without amplitude modulation, using two channel carriers of like frequency in relative phase quadrature to identify one of eight signal levels, each signal level is associated with one of eight equispaced radii emanating from the center of an orthogonal matrix or coordinate system. That matrix is divided by its coordinate axes into four quadrants each encompassing three zones of potential signal deviation, i.e. a middle zone centered on the bisector of the quadrant and two lateral zones whose outer boundaries coincide with those of the quadrant. The signals incoming at a receiver input over the two channels are coherently detected and filtered to supply a pair of coordinates defining a point on the matrix generally falling into one of the three zones of a quadrant; upon conversion into digital form, with six modular bits and one sign bit each, these signals by their modular bits address one of 4,096 cells of a first read-only memory to call forth one of three two-bit combinations stored in these cells. The bit combination so read out identifies the zone - irrespective of quadrant - defined by the detected coordinates; these bits, together with the sign bits derived from the incoming signals, address one of 12 cells in a second read-only memory which thereupon delivers a three-bit word indicating the corresponding signal level and, if desired, two collateral multibit words fed back to the receiver input for correcting distortions of the next-following signals.

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