位同步也叫码元同步或比特同步，在数字通信系统中，接受端不论采用什么解调方式，都要用到码元同步。再模拟通信中不存在码元同步。我们知道消息是通过一连串的码元来表示并传递的，这些码元一般均具有相同的持续时间，接收端就收这些码元序列时，都必须知道每个码元的起该产生一个码元定时脉冲序列，-Bit synchronization code yuan, also known as synchronous or bit synchronization in digital communication systems, the receiving end of whatever demodulation method to be used in Symbol Synchronization. Then does not exist in analog communication Symbol Synchronization. We know that the message is through a series of codes to represent the yuan and passed, and these codes generally have the same yuan duration of the receiving end of those yards on the income element sequences have to be aware of the effect of each element of the code to generate a Symbol timing pulse sequence,