PCM24 vs. PCM30: Key Differences Explained

This page explores the distinctions between PCM24 and PCM30. Let’s dive in!

PCM, or Pulse Code Modulation, is a method used to convert voice signals into a digital format at a standard rate of 64 Kbps. This involves a three-step process: sampling, quantization, and coding. PCM forms the foundation for digital transmission in telephone systems.

Essentially, PCM is a multiplexing technique. It combines multiple voice and/or data signals for transmission over a single high-speed link. This is achieved using Time Division Multiplexing (TDM), which divides the transmission into either 24 or 30 time slots. Each slot carries information at a rate of 64 Kbps.

PCM24 - The 24-Channel System

PCM24 is a 24-channel system primarily used in the USA and Japan. It’s often referred to as a T1 link.

Image alt: PCM T1 frame

The aggregate data rate for PCM24 is 1.544 Mbps. You can explore the structure of PCM24 channels within a T1 Frame.

PCM30 - The 30-Channel System

PCM30, on the other hand, is a 30-channel system widely used in Europe and other regions, as defined by the CCITT (now ITU-T) standards. It’s commonly known as an E1 link.

Image alt: PCM E1 frame

PCM30 boasts a slightly higher aggregate rate of 2.048 Mbps. Further details on the channel structure can be found when looking at PCM30 channels within an E1 Frame.

Key Differences: PCM24 vs. PCM30

The following table summarizes the key differences between PCM24 and PCM30 systems: