In modern communications systems we want communicate distance farther,capacity larger,and transmission quality better.As one of the key technologies , modem technology has been an important direction of our research. Modulation from analog to digital modulation,from binary to M modulation,has various methods, But they are moving to the development of more high-speed ,more reliable communication system. To a large extent,A system of communication quality dependent on the method used by the modulation. Therefore, the modulation of the study, will directly determine the quality of the communication system.
With the ultra-high-speed digital IC development, Forming filter has been from the previous base-band frequency simulation forming filter into the present-band digital forming filter.Compared with the base analog forming filters,digital base-band forming filter has advantages of high precision and high reliability and high flexibility, And also offers characteristics for large-scale integrated and easy to implement Linear Phase.
This system is mainly to solve the digital base-band signal forming filter and modulation. In this paper, it is mainly introduce BPSK QPSK signal modulation methods and the realization of the phase-shifting signals. It Focuse on the use of MC1496 to achieve the multiplication circuit,and modulation of base-band signal to the intermediate frequency modulation.
