Lecture on Signal Processing and Transmission Impairment

Introduction

• Lecture starts with addressing the continuation from previous discussions on physical layer topics, moving into Chapter 3.
• Slide checks for visibility before proceeding.

Recap of Physical Layer

• Physical layer's main function: Converting data to signals and vice versa.
• Emphasis on the mathematical aspects of data conversion.

Types of Data and Signals

Analog Data

• Continuous in nature; e.g., flowing of data in a clock's hands.
• Example given: Voice recordings.

Digital Data

• Discrete in nature; e.g., digital clock displaying exact numbers.
• Binary form (0s and 1s).

Analog vs. Digital Signals

Analog Signals

• Continuous range and infinite number of values.

Digital Signals

• Discrete values; finite number within a range (e.g., 0, 1, 2).

Periodic and Non-Periodic Signals

Periodic Signals

• Repeats patterns over time; examples include sine waves.

Non-Periodic Signals

• No repeating pattern over time; example is human speech.

Complex Composite Signals

Simple Periodic Signal

• Indicates a single sine wave.

Composite Periodic Signal

• Multiple sine waves combined; can be decomposed into simpler signals.

Signal Characteristics

Amplitude

• Measured as the peak of the sine wave; can be positive or negative but measured in absolute terms.

Frequency

• Number of cycles per second (Hertz, Hz).

Phase

• Describes the position of the wave in terms of degrees (0°, 90°, 180°, 270°, 360°).
• Significant in distinguishing different phase offsets.

Wavelength and Propagation Speed

• Relation: Wavelength (λ) = Propagation speed (C) * Time period (T).
• Example given with calculations using light speed.

Frequency Domain Representation

• Transforming signals from time domain to frequency domain for easier analysis.
• Visual example with amplitude and frequency representation.

Digital Signal Concept

• Digital signals with binary levels (e.g., 0 and 1) vs. multiple levels for higher bits per second.
• Relationship: Number of levels = 2^number of bits.
• Example with bits per second calculation.

Signal Impairment Causes

Attenuation

• Loss of signal energy over distance, measured in decibels (dB).

Distortion

• Signal alteration due to propagation speed differences in various mediums.

Noise

• Types: Thermal, Cross-talk, Induced, Impulse noise.
• Effects on signal clarity and accuracy.

Signal-to-Noise Ratio (SNR)

• Measure of signal quality: Power of signal vs. power of noise.
• Conversion to decibels for practical measurements.

Homework and Exam Preparation

• Midterm preparation: Study slides and books, focusing on signal processing calculations and understanding.

Attendance Acknowledgment

• Roll call and student acknowledgment throughout the lecture.