Constructing "broad sense complementary" sequences of length 4N

It is shown that it is possible to construct sets of binary sequences each of length equal to 4^N (where N is any natural number), which have the property that the sum of their 2^N truncated autocorrelation functions is zero except for zero shift. The number of such sequences in any set is equal to 2^N. The autor uses the term "broad sense complementary" sequences to describe the sets of codes with the above properties.