It mainly includes two parts : the frequency offset caused by the difference of the mobile equipment ’ s transmitting frequency and the nodeb ’ s receiving frequency ; the frequency offset caused by the vehicle of the mobile equipment , which is called doppler shift . accurate frequency offset estimation and compensation is of importance for demodulation 它主要由两部分构成:由于nodeb (基站)和移动台晶振本振频率的不同而产生频偏;由于移动台运动产生多普勒效应,引起的多普勒频偏,在信号功率谱上表现为多普勒频谱扩展(以后简称多普勒扩展) 。
There are two major errors . the first one is the error occurred in measuring v . although astronomers can locate v of individual galaxy accurately through the spectrum and the doppler s effect , owing to the gravitational pull exerted from neighbouring galaxies and clusters of galaxies , v is not wholly determined by the expansion of the universe 有两个主要的误差：第一个是测量退行速度的误差，虽然天文学家利用光谱及多普勒效应，已经很准确地找到个别星系的退行速度，但由于与邻近星系及星系团的引力作用，这个退行速度便不完全是因宇宙膨
