Digital Communication Systems Overview

What are the main elements of a digital communication system?

• Modem, Router, Firewall, Switch

• Encoder, Decoder, Amplifier, Filter

• Signal, Noise, Protocol, Bandwidth

• Source, Transmitter, Channel, Receiver, Destination

Explain the advantages of Pulse Code Modulation (PCM).

• Incompatibility with analog systems

• Complex processing requirements

• Advantages of Pulse Code Modulation (PCM) include high fidelity, noise resistance, ease of processing, and compatibility with digital systems.

• Low fidelity and high noise susceptibility

What are the disadvantages of Pulse Code Modulation (PCM)?

• Simple processing requirements

• Low power consumption

• High fidelity audio reproduction

• Disadvantages of PCM include high bandwidth usage, larger data size, noise susceptibility, and complexity in processing.

Define sampling in the context of PCM.

• Sampling is the process of converting digital signals into analog signals.

• Sampling is the process of taking discrete measurements of an analog signal at regular intervals in PCM.

• Sampling refers to the compression of audio data in PCM.

• Sampling involves amplifying an analog signal before transmission.

What is quantization and why is it important in PCM?

• Quantization is the process of amplifying signal values for better clarity.

• Quantization refers to the compression of digital files for storage efficiency.

• Quantization is the method of filtering out noise from digital signals.

• Quantization is the process of converting continuous signal values into discrete levels, and it is important in PCM for enabling digital representation of analog signals.

Describe quantization error and its impact on PCM.

• Quantization error has no effect on the quality of PCM signals.

• Quantization error is the difference between the actual analog value and the quantized digital value, impacting PCM by introducing distortion and noise.

• Quantization error only occurs in analog systems, not in PCM.

• Quantization error is the same as sampling error in PCM.

What is companding in PCM systems?

• A method to increase the bit rate of PCM signals

• A technique for encoding video signals

• A process to eliminate noise from audio signals

• Companding is a technique used in PCM systems to compress and expand audio signals to reduce dynamic range and improve signal quality.

Explain Differential Pulse Code Modulation (DPCM).

• DPCM is a method for compressing images without any loss.

• DPCM encodes the absolute values of each sample directly.

• DPCM encodes the difference between successive samples to reduce data size.

• DPCM uses only the average of all samples for encoding.

What is Delta Modulation and how does it differ from PCM?

• Delta Modulation uses multiple bits to encode differences between samples.

• PCM encodes differences between samples using one bit.

• Delta Modulation and PCM are the same encoding technique.

• Delta Modulation encodes differences between samples using one bit, while PCM encodes absolute sample values using multiple bits.

Describe Adaptive Delta Modulation and its advantages.

• Adaptive Delta Modulation is primarily used for video compression.

• Adaptive Delta Modulation improves signal representation by adjusting the step size based on signal changes, leading to better accuracy and reduced bit rate compared to standard delta modulation.

• Adaptive Delta Modulation increases the bit rate for better signal quality.

• Adaptive Delta Modulation uses a fixed step size for all signal changes.