Direct digital synthesis (DDS) is an all digital frequency synthesis technique. Because of its special theory and construction, it has many kinds of modulationcapability.
直接数字式频率合成(DDS)技术是一种全数字频率合成技术，其特殊的原理和结构使它具有多种调制能力。
2
OFDM is a modulation method which was often used in the channels. It has better capability against the fading and can realized parallel transmission.
正交频分复用调制（OFDM）是一种信道利用率很高的调制方式，具有良好的抗衰落能力，可实现并行传送。
3
As a result, the computer simulations show that the LPI capability of the new DSSS modulation become more effective within the same bandwidth and Spread Spectrum gain.