PCM System Signal Flow: Transmission to Reception

The Pulse Code Modulation (PCM) system transforms an analog signal into a digital format for transmission and subsequently reconstructs it. The process follows a specific sequence:

Transmitter Operations

• A. Sampling and Quantization: This is the first step where the continuous analog signal is sampled at regular intervals, and its amplitude is assigned a discrete value from a predefined range.
• D. Encoding: The quantized samples are then converted into a binary code (digital format) suitable for transmission.

The encoded digital signal is then transmitted through the communication channel.

Receiver Operations

• B. Quantization and Decoding: At the receiver, the incoming digital data is decoded back into discrete amplitude levels. The 'Quantization' part in the option likely refers to mapping the decoded bits back to levels, with the primary action being 'Decoding'.
• C. Holding Circuit: This circuit holds each decoded level constant until the next level is received, creating a staircase approximation of the signal.
• E. Low Pass Filter (LPF): The final step involves passing the staircase signal through a low-pass filter to smooth it, remove unwanted high-frequency noise, and reconstruct an analog signal resembling the original.

PCM Signal Processing Sequence

Arranging the given stages in the order they occur from signal transmission to reception in a PCM system yields the following sequence:

1. A: Sampling and Quantization (Transmitter)
2. D: Encoding (Transmitter)
3. B: Quantization and Decoding (Receiver - primarily Decoding)
4. C: Holding Circuit (Receiver)
5. E: Low Pass Filter (LPF) (Receiver)

The correct sequence is therefore A, D, B, C, E.