基于FPGA的2CPFSK全数字中频调制器的设计与实现

Design and implementation of 2 CPFSK full digital intermediate frequency CPFSK modulator based on FPGA

针对飞行器数据链中高码速率要求,需要使用数字技术实现传统模拟调制,以得到更好的调制性能,增加系统作用距离。本文介绍了二进制连续相位频移键控(2CPFSK)调制原理,提出了基于软件无线电架构的2CPFSK正交调制算法。该算法利用2CPFSK相位累加特性实现了基带数据的分数倍内插,从而适应宽范围码速率的调制。设计了提高频谱纯度的数字滤波器、基于FPGA+DAC架构的数字调制器硬件平台并实现算法。通过与传统模拟频率调制(FM)比较,该设计提升了1.7 dB调制性能,增加了系统作用距离。

The digital modulation is necessary in order to meet the requirement of higher signal transmission rate in aerocraft data link.The better modulating performance and the longer communication distance can be achieved by digital modulation.The principle of 2 Continuous Phase Frequency Shift Keying(CPFSK)modulation with binary continuous phase is introduced.A 2CPFSK quadrature modulation algorithm based on software radio architecture is proposed.By using the phase accumulation property of 2CPFSK,the algorithm realizes the fractional interpolation of baseband data to adapt to the modulation of wide range code rate.A digital filter is also designed to improve spectral purity.The hardware platform of digital modulator based on Field Programmable Gate Array+Digital-to-Analog Converter(FPGA+DAC)architecture is designed and the algorithm is implemented.Compared with traditional analog Frequency Modulation(FM),this design improves the link performance by 1.7 dB and increases the communication distance of the system.