AM and FM lessons of am and fm presentation.pptx

am and fm

1. ee A

a QUARTER WEEK 1

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2. Amplitude and
Frequency,
Modulation

Knowing the difference

3. 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.

7

4. Activity 1: Know My Station

What are the frequencies and names

AM Radio Station

Frequency

Ex. DZRH Nationwide

666

of some radio stations in the

Philippines and the locality?

Turn the radio on.

FM Radio Station

Name and locate the amplitude or

Ex. Love Radio

frequency of the three AM and FM

radio stations that can be heard on

the radio.

7

5. 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 De =
radio wave resembles a huge doughnut ee ee
lying on the ground, with the antenna in
the hole at the center.

7

Magnetic field B

Es

6. 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.

7

7. sky wave

Propagation |
Radio-wave transmission 4 h
reaching beyond line of sight f
by means of the sky wave Pt

reflected by the ionosphere (EA
and by means of the ground \
wave

+ —

© Encyclopedia Britannica, Inc.

8. 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.

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9. wa
2 Ways for carrier wave to be modulated

carrier wave generated

1. By changing by the tanger
the amplitude or
height of the
carrier wave
(Amplitude
Modulation).

Amplitude
Modulator

J Amplitude Modulated

. Carrier Wave
AM radio signal transmitted
electrical signal
a of sound produced
REG by the microphone

y
y

7

10. wa
2 Ways for carrier wave to be modulated

2. By changing …

the frequency or ‘ir 7

how fast the WI = | Moduiror AM,
carrier wave CIE
travels
(Frequency
Modulation).

a=

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AN] IH A AR N
INN VLLT AM

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WN AN NN AAW HNN has

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12. wa
Activity 2: Stop! Look! Write! Explain!

Carrier wave
generated by the
transmitter

MINE
N)

Amplitude Modulated
carrier wave AM radio

signal transmitted

Electrical signal of
sound produced by
the microphone

Sound Signal fed to)
the microphone

13. Difference between AM and FM

+ AM stands for Amplitude + FM stands for Frequency
Modulation Modulation

+ AM method of audio
transmission was first
successfully carried out in the

+ FM radio was developed in the
United states in the 1930s,

mid 1870s. mainly by Edwin Armstrong.

+ In AM, a radio wave known as « In FM, a radio wave known as
the "carrier" or "carrier wave" is the "carrier" or "carrier wave" is
modulated in amplitude by the modulated in frequency by the
signal that is to be transmitted. signal that is to be transmitted.
The frequency and phase The amplitude and phase

remain the same. remain the same.

14. Difference between AM and FM

+ AM has poorer sound quality + FM is less prone to
compared with FM, but is interference than AM.
cheaper and can be However, FM signals are

ne = pi en impacted by physical barriers.

bandwidth so it can have FM has better sound quality
more stations available inany due to higher bandwidth.
frequency range. « FM radio ranges in a higher
+ AM radio ranges from 535 to spectrum from 88 to 108
1705 KHz (OR) Up to 1200 MHz. (OR) 1200 to 2400 bits

bits per second per second.