基于多相滤波的数字正交检波滤波器的选择

分析了不同的多相滤波器对基于多相滤波的数字正交检波器性能所造成的影响。提出了4种多相滤波器选择方案:从32阶原型滤波器依次抽取出4个分支滤波器,取1、3分支为方案一,2、4分支为方案二;对32阶原型滤波器进行1/2抽取得到方案三,方案四是16阶原型滤波器的1/2抽取。它们均能在带宽内实现大于60dB的镜频抑制比,且不需混频,但在边带的镜频抑制比和实现的难易程度不同。在实际应用中,可根据实际情况选择不同的方案,具有很强的实用价值。

Choice of Digital Quadrature Demodulation Based on Ployphase Filter

The analysis of the effect of different ployphase filters on the digital quadrature demodulation has been made.Four implementations on choosing filters are proposed to make a good choice of ployphase filter:the first is the first and third branch filters achieved by dividing thirty-two-order antetype filter into four branch filters,and the second the second and the forth;the third is achieved by dividing thirty-two-order antetype filter into two ,and the four by dividing sixteen-order into two.All of them can achieve the image rejection ratio greater than60dB in signal bandwidth and it is not necessary to do mixing,but have different image rejection ratios in side band and different difficulty in implementations.In practice,it is necessary to choose different implementation based on different practicality.They are of great value in practice.