ordering a Gray Code sequence of U=2^M distinct path numbers, wherein each of the path numbers is an M-bit binary number and is different from adjacent path numbers in the Gray Code sequence by only one bit;

utilizing a function g(u) to record bit positions in which a (u+1)-th path number is different from a u-th path number in the Gray Code sequence, wherein u=0, 1, . . . , U−1 is an index number and g(u) has an integer value between 0 and M−1 inclusive; and

utilizing a function s(u) to record types of changes at recorded bit positions of the function g(u), wherein

modulating a frequency-domain input vector comprising a plurality of path vectors by applying a Gray code sequence of combinations of binary phase rotations identified by the Gray Code sequence of distinct path numbers to the plurality of path vectors, where, in each combination, the binary phase rotation of only one of the plurality of path vectors is changed from a previous combination in the Gray code sequence of combinations of binary phase rotations; and

determining an optimal time-domain peak value based on the modulated frequency-domain input vector;

wherein the frequency-domain input vector is X and the plurality of path vectors are V_m, where m=0, 1, . . . , M−1 and M is an integer, such that

wherein the steps of modulating a frequency-domain input vector and determining an optimal time-domain peak value further comprise the steps of:

calculating a time-domain equivalent x of the frequency-domain input vector X;

calculating a time-domain equivalent v_m of the plurality of path vectors V_m;

establishing a sequence of time-domain vectors x_u, where x₀=x and x_u+1=x_u+2v_g(u)s(u);

calculating a peak value for each of the sequence of time-domain vectors x_u; and

determining an index number for a time-domain vector that has the optimal time-domain peak value among the sequence of time-domain vectors x_u, and a corresponding path number.