6.1、采样率降低——整数M倍抽取 0.5 -0.5 5 0.5 468101214161820 T MT M6.1、采样率降低——整数Ｍ倍抽取  =  M T T M f T MT f s s =  =    = 0 5 10 15 20 25 30 35 40 -1 -0.5 0 0.5 1 x(n) 0 2 4 6 8 10 12 14 16 18 20 -1 -0.5 0 0.5 1 y(m)