Answer :
Final answer:
Pulse Code Modulation involves sampling, quantization, and encoding to convert analog signals to digital. Quantization noise is significant, and techniques like improving quantization levels and using companding can enhance the Signal-to-Quantization Noise Ratio (SQNR). PCM is crucial in modern digital communication systems.
Explanation:
Understanding PCM (Pulse Code Modulation)
Pulse Code Modulation (PCM) is a method used to digitally represent analog signals. The basic concept involves three key processes: sampling, quantization, and encoding.
1. Sampling
The first step, sampling, involves measuring the amplitude of the analog signal at regular intervals. The rate of sampling must satisfy the Nyquist rate, which states that it should be at least twice the maximum frequency of the signal being sampled.
2. Quantization
The second step, quantization, involves mapping the sampled amplitudes to discrete levels. This introduces quantization noise, which is the difference between the actual signal and the quantized signal. The significance of quantization noise in PCM is critical: it can degrade the quality of the transmitted signal.
3. Encoding
Finally, encoding converts the quantized values into binary numbers for digital transmission or storage. This binary representation is the output of a PCM system.
Improving SQNR in PCM
The Signal-to-Quantization Noise Ratio (SQNR) can be improved through several techniques, such as:
- Using a finer quantization: This means increasing the number of quantization levels, which reduces the quantization step size and improves SQNR.
- Companding: This is a technique that compresses the dynamic range of the signal before quantization, which helps in minimizing quantization noise particularly for low-amplitude signals.
In summary, PCM is essential for converting analog signals into a digital format suitable for transmission.
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