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This article describes the basic principles and characteristics of the direct digital frequency synthesis (Direct Digital Synthesizer, DDS) , analysis of the DDS for the modulation principle , given the variety of programs the of GMSK, π/4DQPSK and QAM modulation , while its preliminary performance analysis . On this basis , to achieve a π/4DQPSK , QPSK and QDPSK three kinds of digital modulation . In the hardware implementation of VLSI CPLD ASIC design , thereby improving the reliability of the system , integration, maintainability , while increasing the speed of the system . Studies have shown that the DDS technology supplemented by a microcomputer DDS modulator capable of a variety of modulation functions rolled into one , to provide a new avenue of research for the modulation and demodulation techniques .
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