ITPEC FE Morning April 2018 Question 25

PCM Sampling — identify the step that captures analog values at regular intervals.

PCM (Pulse Code Modulation) digitizes audio in three steps:

• •Sampling — capture analog signal values at regular time intervals
• •Quantization — round each sample to the nearest discrete level
• •Encoding — convert quantized values into binary code

The key phrase is "capture analog values at a regular interval" → this is Sampling.

Why not others:
- (a) Encoding — final step, converts to binary, not capturing values
- (b) Reverse quantization — inverse process used in decoding, not in PCM capture
- (c) Quantization — rounds already-captured values, not the capture itself

Key rule: PCM order is S → Q → E: Sample first, Quantize second, Encode third.

AI-generated — may contain errors