What function does PCM serve in the public switched telephone network?

What function does PCM serve in the public switched telephone network?

• A. It compresses audio for video streaming.
• B. It converts the analog voice signal into digital form to allow many calls on the same wire.
• C. It amplifies signals for long-distance transmission.
• D. It encrypts calls for security.

Answer: (B)

Pulse Code Modulation in the public switched telephone network is the process of turning the continuous analog voice into a digital form so many calls can share the same wire. The voice is sampled at a fixed rate (8000 samples per second) and each sample is quantized into digital values (typically 8 bits), producing a 64 kbps digital stream per channel. This digital representation lets multiple channels be multiplexed and routed through the digital switching and transmission system, enabling efficient, reliable communication over the same physical line. It isn’t about compressing the signal, amplifying it, or encrypting it by itself; the main function is converting analog voice into digital form to support multiplexing and digital transmission.

Pulse Code Modulation in the public switched telephone network is the process of turning the continuous analog voice into a digital form so many calls can share the same wire. The voice is sampled at a fixed rate (8000 samples per second) and each sample is quantized into digital values (typically 8 bits), producing a 64 kbps digital stream per channel. This digital representation lets multiple channels be multiplexed and routed through the digital switching and transmission system, enabling efficient, reliable communication over the same physical line. It isn’t about compressing the signal, amplifying it, or encrypting it by itself; the main function is converting analog voice into digital form to support multiplexing and digital transmission.