FIR digital filter and method for signal processing thereof

A Finite Impulse Response (FIR) digital filter of which impulse response S(t) meets an equation, S(t)=H(t)exp(j.omega.t), where H(t) represents roll off characteristics and .omega. is an arbitrary frequency, said FIR digital filter comprising:

• a data storing means for delay-storing real number data and imaginary number data of a plurality of binary complex input data;
• a coefficient storing means for storing real number coefficients and imaginary number coefficients of said FIR digital filter corresponding to s(0), s(1), . . . , s((N-1)/2) when N is an odd number, and storing real number coefficients and imaginary number coefficients of said FIR digital filter corresponding to s(0), s(1), . . . , s(N/2-1) when N is an even number, where s(0) to s(N-1) represent an impulse response string;
• a reversible counting and reading out means for reading said real number coefficients and imaginary number coefficients stored in said coefficient storing means in order of s(0), s(1), . . . , s((N-1)/2) at first order and s((N-3)/2)), . . . , s(1), s(0) next at second order when N is the odd number, or reading said real number coefficients and imaginary number coefficients stored in said coefficient storing means in order of s(0), s(1), . . . , s(N/2-1) at first order and s(N/2-1), . . . , s(1), s(0) next at second order when N is the even number;
• a sign control means for reversing a sign of the imaginary number coefficients which were read out at said second order by said reversible counting and reading out means;
• a control means for controlling said data storing means, said reversible counting and reading out means and said sign control means;
• a first multiplier for multiplying a real number data output from said data storing means and a real coefficient read out from said coefficient storing means;
• a second multiplier for multiplying an imaginary number data output from said data storing means and a real coefficient read out from said coefficient storing means;
• a third multiplier for multiplying a real number data output from said data storing means and an imaginary coefficient output from said sign control means;
• a fourth multiplier for multiplying an imaginary number data output from said data storing means and an imaginary coefficient output from said sign control means;
• a first accumulating means for accumulating output of said first multiplier and output of said fourth multiplier;
• and
• a second accumulating means for accumulating output of said second multiplier and output of said third multiplier.

A Finite Impulse Response (FIR) digital filter of which impulse response S(t) meets an equation, S(t)=H(t)exp(j.omega.t), where H(t) represents roll off characteristics and .omega. is an arbitrary frequency, comprising:

• a data storing means for delay-storing real number data and imaginary number data of a plurality of binary complex input data;
• a coefficient storing means for storing real number coefficients and imaginary number coefficients of said FIR digital filter corresponding to s(0), s(1), . . . , s((N-1)/2) when N is an odd number, and storing real number coefficients and imaginary number coefficients of said FIR digital filter corresponding to s(0), s(1), . . . , s(N/2-1) when N is an even number, where s(0) to s(N-1) represent an impulse response string;
• a reversible counting and reading out means for reading said real number coefficients and imaginary number coefficients stored in said coefficient storing means in order of s(0), s(1), . . . , s((N-1)/2) at first order and s((N-3)/2)), . . . , s(1), s(0) next at second order when N is the odd number, or reading said real number coefficients and imaginary number coefficients stored in said coefficient storing means in order of s(0), s(1), s(N/2-1) at first order and s(N/2-1), . . . , s(1), s(0) next at second order when N is the even number;
• a sign control means for reversing a sign of the imaginary number coefficients which were read out at said second order by said reversible counting and reading out means;
• a control means for controlling said data storing means, said reversible counting and reading out means and said sign control means;
• a first multiplier for multiplying a real number data output from said data storing means and a real coefficient read out from said coefficient storing means;
• a second multiplier for multiplying an imaginary number data output from said data storing means and a real coefficient read out from said coefficient storing means;
• a third multiplier for multiplying a real number data output from said data storing means and an imaginary coefficient output from said sign control means;
• a fourth multiplier for multiplying an imaginary number data output from said data storing means and an imaginary coefficient output from said sign control means;
• a first accumulating means for accumulating output of said first multiplier and output of said fourth multiplier;
• a second accumulating means for accumulating output of said second multiplier and output of said third multiplier;
• a second sign reversing means for reversing a sign of output of said fourth multiplier;
• a third accumulating means for accumulating output of said second sign reversing means and output of said first multiplier;
• a third sign reversing means for reversing a sign of output of said third multiplier;
• and
• a fourth accumulating means for accumulating output of said third sign reversing means and output of said second multiplier.

A signal processing method of a Finite Impulse Response (FIR) digital filter of which impulse response S(t) meets an equation, S(t)=H(t)exp(j.omega.t) and the impulse response string is represented by s(0) to s(N-1), where H(t) represents roll off characteristics and .omega. is an arbitrary frequency, comprising:

• (a) a step of storing real number coefficients and imaginary number coefficients of said FIR digital filter corresponding to s(0), s(1), . . . , s((N-1)/2) when N is an odd number, and storing real number coefficients and imaginary number coefficients of said FIR digital filter corresponding to s(0), s(1), . . . , s(N/2-1) when N is an even number;
• (b) a step of sequentially reading out said real number coefficients stored and imaginary number coefficients stored in order of s(0), s(1), . . . , s((N-1)/2) at first order and s((N3)/2), . . . , s(1), s(0) next at second order when N is the odd number, or reading out said real number coefficients stored and imaginary number coefficients stored in order of s(0), s(1), . . . , s(N/2-1) at first order and s(N/2-1), . . . , s(1), s(0) next at second order when N is the even number;
• (c) a step of controlling sign of said imaginary number coefficient by not changing a sign of said imaginary number coefficient when said imaginary number coefficient have been read out at said first order, and by reversing the sign of said imaginary number coefficient when said imaginary number coefficient has been read out at said second order;
• (d) a step of generating real number data and imaginary number data of a plurality of binary complex input data;
• and
• (e) a step of calculating sums of products said real number data, said imaginary number data, said real number coefficient read out in said (b) and the sign-controlled imaginary number coefficients in step (c).