在多普勒效应中,我们关心的是观察者接收到的频率和波源发出的频率的大小关系,其相对介质的运动可分为两种最基本的运动类型———波源不动观察者运动和观察者不动波源运动。其它的相对运动都可以由这两种情况演化而成。由于运动本身是相对的,因此这两种基本类型在不同的惯性系 In the Doppler effect, we are concerned about the relationship between the frequency received by the observer and the frequency emitted by the wave source. The motion of the relative medium can be divided into two kinds of the most basic types of motion—the motion of the source-less observer. And the observer does not move the wave source. Other relative movements can evolve from these two situations. Since the movement itself is relative, these two basic types are in different inertial systems.