RFPCM24 vs. PCM30: Key Differences Explained
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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:
| Specifications | PCM24 | PCM30 |
|---|---|---|
| Sampling Frequency (KHz) | 8 | 8 |
| Duration of time slot (µS) | 5.2 | 3.9 |
| Bit Width (µS) | 0.65 | 0.49 |
| Bit Transfer Rate (Mbps) | 1.544 | 2.048 |
| Frame Period (µS) | 125 | 125 |
| No. of bits per word | 8 | 8 |
| No. of frames per multiframe | 12 | 16 |
| Multiframe period (ms) | 1.5 | 2 |
| Frame alignment signal in | Odd frames | Even Frames |
| Frame alignment word | 101010 | 0011011 |
| Multiframe alignment word | 001110 | 0000 |
