Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 2nd Term
Week: 9
Age: 15 years
Duration: 45 minutes
Subject: Radio, Tv & Electronics
Curriculum Theme: Trade
Previous Lesson: Electronic Communication Systems: Block Diagram And Stage Functions.
Topic: ELECTRONIC COMMUNICATION SYSTEMS
Subject Matter: Noise in communication systems, Internal noise, External noise, Effects of noise

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define noise in communication systems.
Identify the causes of internal noise.
Identify the causes of external noise.
List the effects of noise on communication quality.

Affective Domain:

Appreciate the importance of minimizing noise in electronic communication.
Show concern for clear and reliable communication.

Psychomotor Domain:

Distinguish between internal and external noise from examples.
Relate real-life examples of noise interference to their causes.

Discuss the impact of noise on daily communication experiences.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Senior Secondary Schools.
State Unified Scheme of Work for Radio, TV & Electronics (SSS 1).
Anyanwu, J.A. (2018). Radio, TV and Electronics for Senior Secondary Schools 1-3. Lagos: Learnwell Publishers.

Instructional Materials

The teacher will teach this lesson with the aid of:

An audio interference demonstration kit (e.g., a radio with poor signal).
A signal chart showing clean and noisy signals.
Whiteboard and markers.

Rationale for the Lesson

Understanding noise is important because it affects the quality and reliability of all electronic communication systems, from radios to mobile phones. This lesson helps pupils recognize different types of noise and their impact, enabling them to appreciate the need for clear communication and methods to reduce interference.

Prerequisite/Previous Knowledge

Pupils should have a basic understanding of what a communication system is and its components (transmitter, receiver, channel).

Lesson Content/Board Summary

ELECTRONIC COMMUNICATION SYSTEMS: NOISE IN COMMUNICATION SYSTEMS

Definition of Noise

Noise in a communication system refers to any unwanted signal that interferes with the desired signal, thereby degrading the quality of communication. It can be natural or man-made.

Types of Noise

Noise in communication systems can be broadly classified into two main types:

Internal Noise: This type of noise is generated within the electronic components and circuits of the communication system itself.
External Noise: This type of noise originates from sources outside the communication system and enters the system through the antenna or other interfaces.

Causes of Internal Noise

Internal noise is caused by the inherent characteristics and operations of electronic devices. The following are common causes of internal noise:

Thermal Noise (Johnson-Nyquist Noise): Caused by the random thermal motion of electrons within a conductor, especially in resistors. It is present in all electronic components and increases with temperature.
Shot Noise: Arises from the random fluctuations in the arrival rate of charge carriers (electrons or holes) in electronic devices like diodes and transistors.
Flicker Noise (1/f Noise): This is low-frequency noise observed in almost all electronic devices, especially at lower frequencies. Its power is inversely proportional to frequency.

Causes of External Noise

External noise comes from various sources in the environment. The following are common causes of external noise:

Atmospheric Noise: Caused by natural phenomena in the atmosphere, such as lightning discharges and other electrical disturbances.
Man-Made Noise: Generated by human activities and electrical equipment, including car ignition systems, electric motors, fluorescent lights, power lines, and industrial machinery.
Cosmic Noise (Extraterrestrial Noise): Originates from outside the Earth’s atmosphere, primarily from the sun, distant stars, and other celestial bodies.

Effects of Noise in Communication Systems

Noise has several undesirable effects on the performance of communication systems. The following are some key effects:

Signal Distortion: Noise alters the original waveform of the signal, leading to a distorted output.
Reduced Clarity and Intelligibility: Noise makes it difficult to understand speech or clearly see images, reducing the intelligibility of the message.
Loss of Information: High levels of noise can mask the desired signal completely, leading to the loss of transmitted information.
Reduced Signal-to-Noise Ratio (SNR): Noise decreases the ratio of signal power to noise power, indicating a poorer quality signal.
Increased Error Rate: In digital communication, noise can cause bits to be misinterpreted, leading to a higher bit error rate.
Reduced Range of Communication: The presence of noise limits how far a signal can be transmitted and still be reliably received.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them about their experiences with unclear radio or TV signals. The teacher then uses an audio interference demo (e.g., a poorly tuned radio) to demonstrate how noise affects sound, asking pupils to describe what they hear.
Pupils’ Activity: Pupils respond to the teacher’s questions and listen to the audio demonstration, describing the experience of interference.
Learning Point: Pupils are introduced to the concept of noise and its impact on communication.

Step 2: Definition of Noise

Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines noise in the context of communication systems as any unwanted signal that interferes with the desired signal. The teacher writes the definition on the board.
Pupils’ Activity: Pupils listen attentively, take notes, and ask questions for clarification.
Learning Point: Pupils understand the fundamental definition of noise in communication.

Step 3: Types of Noise

Time: 8 minutes
Teaching Skill: Categorization/Explanation
Teacher’s Activity: The teacher explains the two main types of noise: internal and external noise, providing simple examples for each. The teacher uses the signal chart to illustrate how noise contaminates a clean signal.
Pupils’ Activity: Pupils observe the chart, listen to the explanations, and try to differentiate between internal and external noise based on the given examples.
Learning Point: Pupils can distinguish between internal and external noise.

Step 4: Causes of Internal Noise

Time: 7 minutes
Teaching Skill: Elaboration/Listing
Teacher’s Activity: The teacher explains the common causes of internal noise, such as thermal noise, shot noise, and flicker noise, giving brief descriptions of each. The teacher emphasizes that these are inherent to electronic components.
Pupils’ Activity: Pupils listen, take notes, and ask questions about how these noises are generated within devices.
Learning Point: Pupils identify specific causes of internal noise.

Step 5: Causes of External Noise

Time: 7 minutes
Teaching Skill: Elaboration/Listing
Teacher’s Activity: The teacher discusses the causes of external noise, including atmospheric, man-made, and cosmic noise. The teacher provides practical examples for each, relating them to everyday experiences (e.g., static from lightning, interference from car engines).
Pupils’ Activity: Pupils relate the causes to real-world scenarios and contribute examples they might have experienced.
Learning Point: Pupils identify specific causes of external noise.

Step 6: Effects of Noise in Communication Systems

Time: 6 minutes
Teaching Skill: Impact Analysis/Demonstration
Teacher’s Activity: The teacher explains the various effects of noise on communication systems, such as signal distortion, reduced clarity, loss of information, and increased error rates. The teacher can refer back to the audio interference demo to reinforce these effects.
Pupils’ Activity: Pupils list the effects of noise and discuss how these effects impact communication quality.
Learning Point: Pupils understand the negative consequences of noise on communication.

Step 7: Evaluation/Review

Time: 5 minutes
Teaching Skill: Questioning/Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define noise in electronic communication systems.
Mention two types of noise in communication.
State two causes of internal noise.
List three effects of noise on communication quality.

Pupils’ Activity: Pupils answer orally and in writing.
Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the definition, types, causes, and effects of noise. The teacher assigns homework: “Research and write down two methods used to reduce noise in communication systems.”
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their understanding of noise in communication systems.

Lesson Keywords

Noise – Any unwanted signal that interferes with a desired signal in a communication system.
Internal Noise – Noise generated within the electronic components of a communication system.
External Noise – Noise originating from sources outside the communication system.
Thermal Noise – Noise caused by random motion of electrons in conductors due to temperature.
Shot Noise – Noise caused by random fluctuations in the flow of charge carriers in devices.
Atmospheric Noise – Noise caused by natural atmospheric phenomena like lightning.
Man-Made Noise – Noise generated by human activities and electrical equipment.
Signal Distortion – Alteration of the original signal waveform due to interference.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to explain how noise affects different types of communication (e.g., voice vs. data). For those needing more support, the teacher will provide simplified explanations and more direct examples, perhaps allowing them to sketch examples of noisy vs. clean signals. Visual learners will benefit from the signal chart and practical demonstration, while auditory learners will benefit from discussions and verbal explanations.

Note for teachers using this lesson plan

Encourage pupils to share their personal experiences with signal interference to make the lesson more relatable. Emphasize the practical implications of noise reduction in everyday technologies. Ensure the audio interference demo is clear and audible for all pupils. Review pupils’ notes and provide feedback on their understanding of the concepts.