周期信号直接数字式合成中的波形设计与频谱分析

在利用直接数字式合成方法产生周期信号时,信号的频率分辨率和带宽直接受限于合成系统的工作频率和存储容量。分析了直接数字式信号合成系统的输出频谱与相应波形序列的离散傅里叶交换(DFT)之间的关系,在此基础上设计出3种波形序列,其中两种序列能够在不改变合成系统工作频率和存储容量并且不影响合成信号幅频包络的情况下提高其频率分辨率,可用于某些宽带高频率分辨率周期信号的直接数字式合成,另一种序列可用于在波形数据限定的情况下对合成信号的频谱按一定规律进行调整。图1,参8。

Waveform design and spectral analysis in direct digital synthesizing of periodic signals

In the direct digital synthesis of periodic signals, the frequency resolutions and bands of the synthesized signals are limited by the working frequency and data capacity of the synthesizing system. In this paper, the relationship between the output spectrum of a direct digital signal synthesizing system and the DFT of the corresponding waveform sequence is analyzed. Then three waveform sequences are designed, two of which can improve the frequency resolution of synthesized signals without changing the amplitude envelopes of their spectra based on fixed working frequency and data capacity, and are referable in the direct digital synthesis of some wide-band periodic signals of high frequency resolution. Another sequence can be used to synthesize signals of variable spectrum by certain rules with definite waveform data. 1fig. ,8refs.