In a PDM signal, specific amplitude values are not encoded into codewords of pulses of different weight as they would be in pulse-code modulation (PCM); rather, the relative density of the pulses corresponds to the analog signal's amplitude.

This page compares PCM vs PDM and mentions difference between PCM (pulse-code modulation) and PDM (pulse-density modulation).

Most current digital audio systems use multi-bit PCM (pulse code modulation) to represent the signal. PCM has the advantage of being easy to manipulate. This allows signal processing operations to be performed on the audio stream, such as mixing, filtering, and equalization.

One of the characteristics of a PDM (DSD) bit stream is there is no numerical level represented, just a relative level difference contained in the bit density. In other words, it's a digitally store-able and retrievable analog system.

Mar 22, 2024 · Pulse Duration Modulation (PDM) or Pulse Width Modulation (PWM): It is a type of analog modulation. In pulse width modulation or pulse duration modulation, the width of the pulse carrier is varied in accordance with the sample values of message signal or modulating signal or modulating voltage.

I2S, TDM, and PDM are typically used for inter-IC communication on the same PC board. Others, such as S/PDIF and Ethernet AVB are primarily used for data connections from one PCB to another through cabling. This article will focus on the differences, advantages, and disadvantages of the inter-IC—rather than inter-board— digital audio formats.

A signal that is coded as PCM (pulse code modulation, the coding widely used in digital audio) can be converted to PDM by sampling it at a higher rate (interpolating) and reducing the word length to one bit.

Mar 15, 2021 · Finally, the amplitude of the pulse can be approximately represented by a discrete amplitude value which leads to the pulse code modulation (PCM). Further variants of PCM include delta modulation (DM) and differential PCM (DPCM).

Jul 18, 2022 · PWM duty can change at most once per period, but PDM duty can change every clock cycle. PWM is implemented using a simple counter. The period of the counter determines the resolution of the signal. PDM is implemented using an addition every clock cycle, with the overflow/carry determining the output state.

Oct 24, 2018 · In the context of digital audio systems, PDM is a common interface between microphones and microcontrollers/signal processors. PDM signals represent analog audio signals by sampling the analog microphone waveform at a very high rate with a single bit resolution (on/off) for the amplitude.