Device for the division, at an optimum sampling rate, of a passband signal into its components on two carriers in quadrature

Claim 1

A device for the simultaneous division of a bandpass input signal s(t)=x(t) cos ωot-y(t) sin ωot, ωo being an arbitrary angular velocity and x(t) and y(t) being two components of the input signal s(t), into its components x(t), y(t), according to two carriers cos ωot and -sin ωot in quadrature at the angular velocity ωo, characterized in that it comprises an analog section comprising means (3; 27,28) and (8; 25,26; 27, 28) for filtering and producing a Hilbert transform of the input signal s(t) provided in at least one of the channels of the device, a first sampler (6; 21) for sampling the filtered input signal s(t) and a second sampler (9;22) for sampling the Hilbert transform s(t) of s(t), the first and second samplers having a sampling rate fe controlled by a sampling oscillator at frequency fe, fe being at least 2F, F being the difference between fo=ωo/2π and the frequency of the spectrum of the filtered input signal s(t) which is most distant from fo, and two analog-digital converters (7,10; 23, 24) respectively associated with said first and second samplers (6,9; 21, 22) and operating at the same frequency fe, wherein the frequency fe of the sampling oscillator and its phase are chosen as a function of fo such that at any sampling instant te there is a relationship of the type: cos (ωote)=1 and sin (ωote)=0 or cos (ωote)=-1 and sin (ωote)=1 or cos (ωote)=0 and sin (ωote)=-1 whereby the sampling frequency fe can be chosen to be smaller than fo and the values of the components according to the two carrier in quadrature at ωo, x and y are directly available at the outputs of the analog-digital converters (7, 10; 23, 24) at the sampling instants te and except for the sign depending on case in question.

Claim 2

A device for the simultaneous division of a bandpass input signal s(t)=x(t) cos ωot-y(t) sin ωot, ωo being an arbitrary angular velocity and x(t) and y(t) being two components of the input signal s(t), into its components x(t), y(t), according to two carriers cos ωot and -sin ωot in quadrature at the angular velocity ωo, characterized in that it comprises an analog section comprising means (3; 27,28) and (8; 25,26; 27, 28) for filtering and producing a Hilbert transform of the input signal s(t) provided in at least one of the channels of the device, a first sampler (6; 21) for sampling the filtered input signal s(t) and a second sampler (9;22) for sampling the Hilbert transform s(t) of s(t), the first and second samplers having a sampling rate fe controlled by a sampling oscillator at frequency fe, fe being at least 2F, F being the difference between fo=ωo/2π and the frequency of the spectrum of the filtered input signal s(t) which is most distant from fo, and two analog-digital converters (7,10; 23, 24) respectively associated with said first and second samplers (6,9; 21, 22) and operating at the same frequency fe, wherein the frequency fe of the sampling oscillator and its phase are chosen as a function of fo such that at any sampling instant te there is a relationship of the type: cos (ωote)=1 and sin (ωote)=0 or cos (ωote)=-1 and sin (ωote)=1 or cos (ωote)=0 and sin (ωote)=-1 whereby the sampling frequency fe can be chosen to be smaller than fo and the values of the components according to the two carrier in quadrature at ωo, x and y are directly available at the outputs of the analog-digital converters (7, 10; 23, 24) at the sampling instants te and except for the sign depending on case in question.