直接串行扩频（direct-sequence spread spectrum，DSSS），简称直扩（DS），是一种调制技术。就是在发送端，直接用高码率的扩频码串行去扩展信号的频谱，在接收端，用相同的扩频码串行将信号解扩，把展宽的信号还原到原始状态。其名称中的“扩频”来自这样一个事实，即载波信号发生设备的发射频率充满了整个带宽（频谱）。在一些IEEE 802.11标准中，使用了DSSS技术来调制信号。

In the telecommunications, direct-sequence spread spectrum (DSSS) is a spread spectrum modulation technique. Spread spectrum systems are such that they transmit the message bearing signals using a bandwidth that is in excess of the bandwidth that is actually needed by the message signal. This spreading of the transmitted signal over a large bandwidth make the resulting wideband signal appear as a noise signal which allows greater resistance to intentional and unintentional interference with the transmitted signal.