TOKYO, Oct. 17 -- NEC Corp. and Hitachi Ltd. are taking advantage of the growing demand for broadband, high-capacity transmission systems by designing a mutually constructed telecommunications system. The two semiconductor manufacturers will focus on developing next generation dense wavelength division multiplexing systems and synchronous digital hierarchy-based fiber optic transmission systems for the North American market, said Hitachi. The companies chose to target North American because of its 50 percent per-year growth rate for wavelength division multiplexing systems, said Hitachi. The first products designed by the union will be on the market before next fall, said Hitachi.