直接信号扩频的原理是利用一个有周期的伪随机的码序列去调节原始的信号，并用调制的信号区改变载波的相位的方式。-The principle of direct spread spectrum signal is the use of a cycle of pseudo random code sequence to adjust the original signal, modulation and signal area change the way of carrier phase.

4FSK水池实验发送端，随机生成的原始数据，键控法产生4FSK信号-4FSK pool experimental transmitter, randomly generated raw data, keying method to generate 4FSK signal