# 脉冲密度调制

（重定向自脈衝密度調變

SSB · DSB
FMPM

OOK · QAM
FSK
MSK · GFSK
PSK
CPM

CSS · DSSS · THSS · FHSS

## 描述

${\displaystyle x[n]=-A(-1)^{a[n]}\ }$

## 例子

0101011011110111111111111111111111011111101101101010100100100000010000000000000000000001000010010101

An example of PDM of 100 samples of one period of a sine wave. 1s represented by blue, 0s represented by white, overlaid with the sine wave.

0101101111111111111101101010010000000000000100010011011101111111111111011010100100000000000000100101

A second example of PDM of 100 samples of two periods of a sine wave of twice the frequency

In pulse-density modulation, a high density of 1s occurs at the peaks of the sine wave, while a low density of 1s occurs at the troughs of the sine wave.

## 参考资料

1. ^ Thomas Kite. "Understanding PDM Digital Audio" (PDF). 2012. The "PDM Microphones" section on p. 6.
2. ^ Maxim Integrated. "PDM Input Class D Audio Power Amplifier" (PDF). 2013. Figure 1 on p. 5; and the "Digital Audio Interface" section on p. 13.
3. ^ Akustica. "AKU230 Digital, CMOS MEMS Microphone" (PDF)页面存档备份，存于互联网档案馆）. 2012. p. 5.