A/D Conversion in Source Encoding | Generated by AI
Question: A/D conversion involves sampling, quantization, and encoding; in which stage is this performed?
Answer:
The process of Analog-to-Digital (A/D) conversion, which includes sampling, quantization, and encoding, is performed during the Source Encoding (or 信源编码) stage in a digital communication system.
Detailed Explanation:
- Sampling: This is the process of converting a continuous-time analog signal into a discrete-time signal by taking samples at regular intervals. According to the Nyquist-Shannon sampling theorem, the sampling rate must be at least twice the highest frequency component of the signal to avoid aliasing.
- Quantization: This step maps the continuous amplitude values of the sampled signal to a finite set of discrete levels. This introduces quantization error (noise) but is necessary for digital representation.
- Encoding: In this final step of A/D conversion, each quantized level is assigned a unique binary code (a sequence of bits).
In the context of a communication system model:
- Source Encoding aims to convert the source information (which may be analog, like voice or video) into a digital bit stream efficiently. It often includes compression and the A/D conversion process itself if the source is analog.
- Channel Encoding follows source encoding and adds redundancy to the bit stream to protect against errors during transmission (e.g., adding parity bits).
- Modulation converts the digital baseband signal into a form suitable for transmission over the physical channel.
Therefore, since A/D conversion transforms the original analog source information into a digital format, it falls squarely under the domain of Source Encoding.
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