Design and analysis of FPGA-based high speed DQPSK modulation system

This paper introduces the implementation principle and scheme of an all-digital high speed differential Quadrature phase-shift keying (DQPSK) modulator. The modulator adopts FPGA and DAC to realize DQPSK modulation, FPGA accomplishes data randomization, differential encoding, channel coding, symbol mapping, shaping filtering, up-converting, and transfers I/Q data to DAC with LVDS interface. With four DDS work concurrently in FPGA, which make it fitful for the occasion of high speed transmission. The index test by instrument and application in pilotless aircraft indicate that the modulator´s index is far excellent than the other method.