Patent ID: 7346137

Claim:
An arrangement comprising: a collection of filters indexed by i, where i=0, 1, 2, . . . n 1 , wherein n 1 is an integer less than N 1 , each having an input that is responsive to a different signal, where filter i has the transfer function V _ 1 ⁡ ( ⅇ j ⁡ ( ω - 2 ⁢ π N 1 ⁢ i ) ) , and V is a time-reversed version of a filter V having high attenuation for frequencies ω>2π/N that is subject to the constraint that ∑ i = 0 N 1 - 1 ⁢ ⁢  V 1 ⁡ ( ⅇ j ⁡ ( ω + 2 ⁢ π N 1 ⁢ i ) )  2 = N 1 for all ω∈(−π, π); and a combiner for adding output signals of said filters to form an output signal of said arrangements.