ELECTRONICS Q3W1 MODULE 1 AM FM - GRADE 10 SCIHS

2. BRAIN TEASER

3. Amplitude and
Frequency
Modulation
Knowing the difference

4. Radio waves
•Radio waves are a type of electromagnetic
radiation best-known for their use in
communication technologies, such as
television, mobile phones and radios.
•These devices receive radio waves and convert
them to mechanical vibrations in the speaker
to create sound waves.

5. Activity 1: Know My Station
What are the frequencies and names
of some radio stations in the
Philippines and the locality?
Turn the radio on.
Name and locate the amplitude or
frequency of the three AM and FM
radio stations that can be heard on
the radio.

6. Formation of radio waves
• A radio wave is generated by a
transmitter and then detected by a
receiver. An antenna allows a radio
transmitter to send energy into space
and a receiver to pick up energy from
space.
• When it leaves a vertical antenna, the
radio wave resembles a huge doughnut
lying on the ground, with the antenna in
the hole at the center.

7. Propagation
• Radio waves transmitted by antennas in
certain directions are bent or even reflected
back to Earth by the ionosphere
• They may bounce off Earth and be reflected
by the ionosphere repeatedly, making radio
transmission around the globe possible.

8. Propagation
Radio-wave transmission
reaching beyond line of sight
by means of the sky wave
reflected by the ionosphere
and by means of the ground
wave

9. Amplitude/frequency modulation
• AM (or Amplitude Modulation) and FM (or Frequency
Modulation) are ways of broadcasting radio signals in which
both transmit the information in the form of electromagnetic
waves.
• AM works by modulating (varying) the amplitude of the signal or
carrier transmitted according to the information being sent,
while the frequency remains constant.
• This differs from FM technology in which information (sound) is
encoded by varying the frequency of the wave and the
amplitude is kept constant.

10. 2 Ways for carrier wave to be modulated
1. By changing
the amplitude or
height of the
carrier wave
(Amplitude
Modulation).

11. 2 Ways for carrier wave to be modulated
2. By changing
the frequency or
how fast the
carrier wave
travels
(Frequency
Modulation).

13. Activity 2: Stop! Look! Write! Explain!
Sound Signal fed to
the microphone
Carrier wave
generated by the
transmitter
Electrical signal of
sound produced by
the microphone
Amplitude Modulated
carrier wave AM radio
signal transmitted

14. Difference between AM and FM
• AM stands for Amplitude
Modulation
• AM method of audio
transmission was first
successfully carried out in the
mid 1870s.
• In AM, a radio wave known as
the "carrier" or "carrier wave" is
modulated in amplitude by the
signal that is to be transmitted.
The frequency and phase
remain the same.
• FM stands for Frequency
Modulation
• FM radio was developed in the
United states in the 1930s,
mainly by Edwin Armstrong.
• In FM, a radio wave known as
the "carrier" or "carrier wave" is
modulated in frequency by the
signal that is to be transmitted.
The amplitude and phase
remain the same.

15. Difference between AM and FM
• AM has poorer sound quality
compared with FM, but is
cheaper and can be
transmitted over long
distances. It has a lower
bandwidth so it can have
more stations available in any
frequency range.
• AM radio ranges from 535 to
1705 KHz (OR) Up to 1200
bits per second
• FM is less prone to
interference than AM.
However, FM signals are
impacted by physical barriers.
FM has better sound quality
due to higher bandwidth.
• FM radio ranges in a higher
spectrum from 88 to 108
MHz. (OR) 1200 to 2400 bits
per second.

17. Modular Activity
• Accomplish Quarter 3
Module 1- Additional
Activity –Performance
task
• Deadline:
next week Friday
(February 25 before
5PM)

18. Examples

19. Assessment
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