一种X波段星载数传发射机成形滤波设计  

A shaping filter design for X-band spaceborne digital transmitter

作　　者：何林飞 李晓飞 韩俊博 HE Linfei;LI Xiaofei;HAN Junbo(Tianjin Xunlian Technology Co.,Ltd.,Tianjin 300308,China)

机构地区：[1]天津讯联科技有限公司,天津300308

出　　处：《电子设计工程》2023年第17期30-34,39,共6页Electronic Design Engineering

摘　　要：针对星载数传发射机的DAC采样时钟频率为110 MHz,符号速率为20 Msps,采样率与符号速率不满足整数倍关系,无法采用常规成形滤波处理的问题,设计一种可以支持非整数倍速率的成形滤波的方法,利用码NCO(数字振荡器)控制对输入码元进行取数和移位,码NCO截短相位实现对成形滤波器系数的ROM寻址。使用Matlab对符号周期Tb内不同相位点数的系数ROM的成形滤波效果进行仿真,得到频谱不失真系数ROM所需最小相位点数。在FPGA中使用Veriolog HDL语言对算法进行了工程化实现,并使用Modelsim软件进行了仿真。在X波段数传发射机硬件平台上采用频谱仪对成形滤波后信号的频谱和EVM(误差矢量幅度)进行了实测,结果表明,加入成形滤波后的信号EVM性能得到了2~3倍提升。Aiming at the problem that the DAC sampling clock frequency of the satellite⁃borne data transmission transmitter is 110 MHz,the symbol rate is 20 Msps,the sampling rate and the symbol rate do not satisfy the integer multiple relationship,and conventional shaping filtering cannot be used.A method of shaping filtering that can support non⁃integer multiple rates is designed.The input data is fetched and shifted by using the code NCO(digital oscillator)control,and the ROM addressing of the stored shaping filter coefficients is realized by the truncated phase of the code NCO.Using Matlab to simulate the coefficient ROM shaping filtering effect of different phase points in the symbol period Tb,the minimum phase points required without spectrum distortion are obtained.The algorithm is implemented in FPGA with Verilog HDL language,and simulated with Modelsim software.The spectrum of the filtered signal and the EVM(Error Vector Magnitude)are measured by a spectrum analyzer on the hardware platform of X-band digital transmitter.The results show that the EVM performance of the signal with shaping filter is improved by 2~3 times.

关 键 词：110 MHz采样时钟频率 成形滤波 非整数倍速率 FPGA 

分 类 号：TN927[电子电信—通信与信息系统]