Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
370 words
A finite impulse response digital filter including (2n+1) successive virtual taps respectively having virtual tap weight coefficient c j , where n≧2 and 1≦j≦2n+1, and c j =c 2n+2-j , said digital filter comprising: (n+1) tap weight multipliers connected to an input terminal of said digital filter for forming (n+1) successive physical taps and multiplying input digital samples a i with physical tap weight coefficients d k to produce weighted digital samples, where 1≦k≦n+1, and d k =c 2k-1 +c 2k =c 2 (n-k+1) +c 2 (n-k+1)+1, and d n+1 =c 1 =c 2n+1 , and a i is an input digital sample at a given instant of time, and a i+1 is an input digital sample displaced by an interval T with respect to said digital sample a i , and T is the reciprocal of the symbol rate of said input digital samples; a first delay-and-adder circuit including a series circuit of first delaying elements and first summing elements alternately series-connected from the output of a first one of said tap weight multipliers, each of said first delaying elements having a delay time T, and said first summing elements summing the outputs of the other tap weight multipliers with successive outputs of the first delaying elements to produce a first output sequence of digital samples d 1 ×a i-n +d 2 ×a i-n+1 + . . . +d n+1 ×a i ; a second delay-and-adder circuit including a series circuit of second delaying and second summing elements alternately series-connected from the output of the (n+1)th of said tap weight multipliers, each of said second delaying elements having a delay time T, and said second summing elements summing the outputs of the other tap weight multipliers with successive outputs of said second delaying elements to produce a second output sequence of digital samples d n+1 ×a i-n +d n ×a i-n+1 +d 2 ×a i-1 +d 1 ×a i ; and means for sampling said first output sequence at intervals T for a first half duration and sampling said second output sequence at intervals T for a second half duration and multiplexing the sampled sequences into a single sequence for coupling to an output terminal of said digital filter.
Claim 2
Dependent Claim
370 words
A finite impulse response digital filter including (2n+1) successive virtual taps respectively having virtual tap weight coefficient c j , where n≧2 and 1≦j≦2n+1, and c j =c 2n+2-j , said digital filter comprising: (n+1) tap weight multipliers connected to an input terminal of said digital filter for forming (n+1) successive physical taps and multiplying input digital samples a i with physical tap weight coefficients d k to produce weighted digital samples, where 1≦k≦n+1, and d k =c 2k-1 +c 2k =c 2 (n-k+1) +c 2 (n-k+1)+1, and d n+1 =c 1 =c 2n+1 , and a i is an input digital sample at a given instant of time, and a i+1 is an input digital sample displaced by an interval T with respect to said digital sample a i , and T is the reciprocal of the symbol rate of said input digital samples; a first delay-and-adder circuit including a series circuit of first delaying elements and first summing elements alternately series-connected from the output of a first one of said tap weight multipliers, each of said first delaying elements having a delay time T, and said first summing elements summing the outputs of the other tap weight multipliers with successive outputs of the first delaying elements to produce a first output sequence of digital samples d 1 ×a i-n +d 2 ×a i-n+1 + . . . +d n+1 ×a i ; a second delay-and-adder circuit including a series circuit of second delaying and second summing elements alternately series-connected from the output of the (n+1)th of said tap weight multipliers, each of said second delaying elements having a delay time T, and said second summing elements summing the outputs of the other tap weight multipliers with successive outputs of said second delaying elements to produce a second output sequence of digital samples d n+1 ×a i-n +d n ×a i-n+1 +d 2 ×a i-1 +d 1 ×a i ; and means for sampling said first output sequence at intervals T for a first half duration and sampling said second output sequence at intervals T for a second half duration and multiplexing the sampled sequences into a single sequence for coupling to an output terminal of said digital filter.
Claim 3
Dependent Claim
25 words
A finite impulse response digital filter as claimed in claim 1, wherein each of said delay elements is a shift register clocked at intervals T.