Patent ID: 6690735
Filing Date: 2004-02-10
Classification: H03D,H04B

Abstract:
A method for the implementation of a broad band receiver for a signal (z1(t)) consisting of a plurality of equispaced carriers, orthogonally modulated by information conveyed by relevant channels (CH1, . . . , CH8) in order to carry out a radiofrequency multicarrier signal; including a radiofrequency filtering with band pass (PBAND) characteristic for the suppression of signals not included in the band of the radiofrequency multicarrier signal and to achieve a radiofrequency filtered signal (z1â€²(t)), said method comprising in sequence the following steps:a) direct demodulation (DEMI/Q) of the radiofrequency filtered signal (z1â€²(t)) by multiplication of said signal for two local phase quadrature carriers (cos &ohgr;0t, âˆ’sin &ohgr;0t) whose frequency corresponds to a central value of the radiofrequency multicarrier signal spectrum, obtaining a demodulated signal having a relevant spectrum in the lower half of the base band (BW) where pairs of channels (CH4, CH5; . . . ; CH1, CH8) in symmetric positions at the two sides of said local phase quadrature carriers are superimposed; b) broad band filtering in base band of in phase (z2â€²(t)) and in quadrature (z3â€²(t) components that correspond to the demodulated signal, for the suppression of additional components outside an interest band; c) sampling of the components broad band filtered in base band (z2â€²(t), (z3â€²(t)), making use of a sampling frequency equal to the bandwidth (BW) of said multicarrier signal, and subsequent analog-to-digital conversion (A/D) of the sampled components, obtaining first digital in phase and in quadrature components; d) digital demodulation (DEM4, DEM5; . . . ; DEM1, DEM8) of said first digital components by multiplication for pairs of relevant phase quadrature sinusoidal digital signals, having frequency equal to the value of center band of pairs of channels (CH4, CH5; . . . ; CH1, CH8) previously superimposed at the step a), obtaining in coincidence with said pairs of phase quadrature sinusoidal digital signals, due to the multiplication, quartets of numeric values (z4(t)4/5, z5(t)4/5, z6(t)4/5, z7(t)4/ 5; . . . ; z4(t)1/8, z5(t)1/8, z6(t)1/8, z7(t)1/8) that can be analytically expressed through linear systems, each of four equations in four unknown values corresponding to amplitudes of second digital in phase (I4, I5; . . . ; I1, I8) and in quadrature (Q4, Q5; . . . ; Q1, Q8) components belonging to said quartets of numeric values; e) solution of said linear systems (RSOM) obtaining said amplitudes of the second digital components (I4, Q4; I5, Q5; . . . ; I1, Q1; I8 Q8) with each single channel of said pairs of channels (CH4, CH5; . . . ; CH1, CH8), thus eliminating phase and amplitude dissymmetry in base band due to the superimposition of channels in the previous step a).