Some Notes on Generalized Cyclotomic Sequences of Length pq

We review the constructions of two main kinds of generalized cyclotomicbinary sequences with length \it pq (the product with two distinctprimes). One is the White-generalized cyclotomic sequences, the other is theDing-Helleseth(DH, for short)-generalized cyclotomic sequences. Wepresent some new pseudo-random properties of DH-generalizedcyclotomic sequences using the theory of character sums instead ofthe theory of cyclotomy, which is a conventional method forinvestigating generalized cyclotomic sequences.