一种改进的数字乘积检波方法  

An Improved Digital Product Detector for Digital Quadrature Demodulation

作　　者：张汉华[1] 宋千[1] 周智敏[1] 

机构地区：[1]国防科技大学电子科学与工程学院,湖南长沙410073

出　　处：《信号处理》2009年第10期1550-1554,共5页Journal of Signal Processing

摘　　要：数字乘积检波(DPD:Digital Product Detector)是一种工程实现数字正交解调的简便方法,该方法克服了模拟正交解调I、Q通道不平衡的缺点,在雷达中频或射频信号采样中得到了广泛应用。然而该方法获得的I、Q数据在时间上不同步,需要进行分数阶多相插值滤波修正,由于分数阶多相插值滤波器无法做到I、Q通道幅度和相位的同时匹配,其不匹配引入的镜像干扰对工作在极低信噪比下的车载前视步进频率雷达来说非常不利。本文从信号与系统基本原理出发,对DPD方法进行改进,提出了一种不需要对I、Q数据进行分数阶多相插值滤波,就可以得到时间同步I、Q数据的正交解调方法,该方法简便灵活,容错性强,用低通滤波器代替分数阶多相插值滤波器,可以做到两个通道幅度和相位的同时匹配,可以很好地控制I、Q分量幅度和相位的一致性。The Digital Product Detector（DPD）, which overcomes the imbalance between the channels introduced by analogue components, is hardware efficient method in the real direct digital quadrature demodulation engineering. But the datum acquired by the method contains time mismatch between in-phase（I） and quadrature（Q） components, which should be removed by applying fractional-phase interpolated filters. The image term, introduced by either magnitude mismatch or phase mismatch of fractional-phase interpolated filters, is harmful to stepped frequency ground penetrating radar working under very low SNR. After study the elementary theory of Signals ＆ System carefulness, an improved DPD without fractional-phase interpolated filters for digital quadrature demodulation is proposed in this paper, which can obtain time matching datum by a general lowpass filter instead of fractional-phase interpolated filters. The improved DPD has more flexible and tolerate, can achieve both magnitude and phase match, and wins better I and Q components performance.

关 键 词：数字乘积检波 数字正交解调 I Q通道 

分 类 号：TN958[电子电信—信号与信息处理]