【摘要】 对Sigma Delta调制与脉冲编码调制进行对比,研究了Sigma Delta调制与脉冲编码调制的优缺点。建立了微加速度计中两位输出的Sigma Delta调制和两位输出的脉冲编码调制的仿真系统。然后,对比使用这两种调制方式的微加速度计的加速度信号,并分析在两种不同调制方式下的输出信号波形的差别。最后,利用周期图法得到了两种调制信号的功率谱密度图,发现在低频段脉冲编码调制信号的量化噪声比Sigma Delta调制信号大很多;而在高频段,两种调制方式信号的量化噪声一样严重。仿真结果表明,尽管Sigma Delta调制系统比脉冲编码调制系统更加复杂,但是Sigma Delta调制得到的信噪比要比脉冲编码调制得到的信噪比高出20dB。更多还原

【Abstract】 A comparative study of the Sigma Delta Modulation(SDM) and the Pulse Code Modulation(PCM) is presented,and the advantages and the disadvantages of the two kinds of modulation are also obtained. A 2-bit SDM simulated system and a 2-bit (PCM) simulated system for a micro-accelerometer are established in this paper. Then,the accelaration signals pass through the modulations are comparatively analyzed,and the difference of two mudulations output waves is obtained by the comparive analysis. Finally,the power spectral density patterns of two kinds of the modulated signals are computed with a periodogram respectively. The power spectral density from experimental results indicates that the quantization noise of the PCM is more serious than that of the SDM in the low frequency,but the quantization noises of both modulation methods are the same in the high frequency. The simulated results show that the SNR of the SDM is 20 dB higher than that of the PCM,though the SDM modulation system is more complex than the PCM.更多还原