MODULATION •Higher amplitudes in the audio signal result

in wider frequency variations.

• the process in which information is encoded into
a carrier signal for transmission.
ADVANTAGE OF FM
• Has three parts: • Noise immunity
•Information/message signal: This is the • Wider audio range
actual message you want to send, like • Efficient bandwidth utilization
your whispered secret. It can be audio • Data transmission capability
(voice, music), video, or even digital • Broader range of applications
data. DISADVANTAGE OF FM
•Carrier signal: This is a high-frequency • More complex technology
wave that can travel long distances, like • Shorter signal range
the balloon. It typically has a steady • Larger bandwidth requirement
amplitude (strength) and frequency
• Susceptibility to multipath interference
(pitch).
•Modulation process: how the
information signal is embedded onto
the carrier signal. • Amplitude Modulation (AM)
- a technique for transmitting information
TYPES OF MODULATION by varying the strength of a high-
frequency carrier wave in proportion to
• Frequency Modulation (FM) the information signal.
- method of encoding information onto a Carrier Wave Variation
carrier wave by varying its frequency • In AM, the amplitude of the carrier wave is
- commonly used for transmitting audio modulated based on the amplitude of the
signals. input signal.
•audio signal is used to modulate the • Changes in the amplitude of the audio signal
frequency of the carrier wave. result in corresponding changes in the
Carrier Wave Variation amplitude of the carrier wave.
• In FM, the carrier wave's frequency is Frequency Deviation
varied based on the amplitude of the • The extent of variation in the amplitude of
input signal. the carrier wave is proportional to the
• As the amplitude of the audio signal amplitude of the audio signal.
changes, it causes corresponding changes • Higher amplitudes in the audio signal result
in the frequency of the carrier wave. in larger variations in the carrier wave
Frequency Deviation amplitude.
Signal Representation
• The extent to which the frequency of the
• Information is encoded in the amplitude
carrier wave varies is known as frequency
variations of the carrier wave.
deviation.
•The variations represent the audio signal,
• The frequency deviation is directly
proportional to the amplitude of the audio and demodulation at the receiver extract this
signal. information.
Signal Representation
• Information is encoded in the frequency
variations of the carrier wave.
ADVANTAGES OF AM FM uses variations in the carrier wave's
• Simple and inexpensive frequency to encode the video signal.
• Penetrative and reliable • FM is chosen for video transmission due to
• Lower bandwidth requirement its resistance to noise and interference,
• Legacy compatibility providing a clearer and more stable visual
DISADVANTAGES OF AM representation. This is crucial for delivering
sharp and vibrant images to television
• Susceptible to noise
screens, enhancing the quality of the viewing
• Lower sound quality
experience.
• Limited bandwidth efficiency
Integration of AM and FM
• Technological limitations
• The integration of AM and FM in television
TV: The Best of Both Worlds broadcasting showcases a harmonious
 Television broadcasting employs a marriage of technologies, each playing a
combination of both Amplitude Modulation specialized role to deliver a comprehensive
(AM) and Frequency Modulation (FM) audio-visual package. AM takes care of
techniques to deliver audio and video audio fidelity, allowing viewers to enjoy
signals to households. The integration of clear and synchronized sound with the
these modulation methods optimizes the visual content. Meanwhile, FM ensures
transmission process, ensuring efficient use the high-quality transmission of the video
of bandwidth while maintaining high-quality signal, contributing to sharp, well-defined
audio-visual content. images on the screen.
AM in TV Broadcasting • In modern digital television (DTV) systems,
• AM is primarily utilized in the audio the principles of AM and FM persist,
transmission component of television although the modulation techniques are
broadcasting. In the analog television system, more advanced. Digital broadcasting often
the audio signal is modulated onto a carrier employs techniques like Quadrature
wave using AM. The amplitude variations in Amplitude Modulation (QAM) for video
the carrier wave correspond to the audio and audio transmission, ensuring efficient
signal's amplitude changes, enabling the use of bandwidth while maintaining signal
reproduction of sound at the receiving end. quality.
• This AM modulation is an essential _____________________________________
component of television broadcasting, as it RADAR (Radio Detection and Ranging)
allows for the simultaneous transmission of • Signal Generation
audio information alongside the video signal.
- Radar systems typically use a high-
The use of AM in this context provides an
frequency oscillator to generate
efficient means of conveying sound,
electromagnetic waves, often in the
contributing to the overall viewing experience.
microwave or radio frequency range.
FM in TV Broadcasting
• Pulse Transmission
• While AM handles the audio component,
- Radars often operate in a pulsed mode.
FM is predominantly employed for video
The transmitter sends out short pulses of
signal transmission in television
electromagnetic energy. The duration and
broadcasting. The video signal, containing
repetition rate of these pulses depend on
visual information, is modulated onto a
the specific radar application.
carrier wave using FM. Unlike AM, where
• Antenna
variations in amplitude represent information,
- An antenna is used to transmit and receive
the radar signals. The same antenna is
 often employed for both functions, with a conditions, such as fog or rain, can affect
switch allowing it to alternate between the quality of the signal.
transmission and reception. ____________________________________________
• Echo Processing TUNERS
- a component or subsystem responsible
- When the transmitted signal encounters a for adjusting the frequency response of
target, it reflects back as an echo. The the circuit to selectively receive signals
radar system analyzes the time delay, within a certain frequency range while
frequency shift (Doppler effect), and rejecting others
amplitude of the received signal to - It's particularly crucial in radio frequency
extract information about the target's (RF) circuits where the receiver needs to
location, speed, and other characteristics. tune into specific frequencies corresponding
to the signals of interest while filtering out
____________________________________________ unwanted frequencies.
LASER (Light Amplifcation by Stimulated
Emission of Radiation) • Manual Tuners
• Signal Generation
- Tuners that requires human intervention
- Laser communication systems use lasers to adjust or tune to specific frequencies
to generate optical signals. These signals or channels
typically fall in the infrared or visible light - usually look likes knobs or dials
spectrum.
• Modulation • Automatic Tuners
- Information is encoded onto the laser
beam by modulating its intensity, - automatically adjusts and tunes to
frequency, or phase. This modulation specific frequencies or channels without
allows the transmission of data in the requiring manual intervention from the
form of light pulses. user
• Optical Fiber or Free Space - commonly found in modern electronic
devices such as televisions, radios,
- Laser signals can be transmitted through
optical fibers or free space. In optical communication systems, and wireless
fiber communication, signals travel routers.
through thin glass or plastic fibers. In DEVICES THAT USE MANUAL TUNING
free-space laser communication, signals • Radios
travel through the air or outer space - an electronic device that receives and
without the need for a physical medium. sometimes transmits electromagnetic
• Photodetection signals primarily in the radio frequency
- At the receiving end, a photodetector (RF) portion of the electromagnetic
detects the incoming optical signals. The spectrum. It converts these signals into
detected signals are then converted back sound, which can be listened to through a
into electrical signals for further speaker or headphones.
processing. • Televisions (older models)
• Line-of-Sight Communication - Older model televisions with knobs
- Laser communication often requires a typically refer to analog televisions that
clear line of sight between the were commonly used before the
transmitter and receiver. Atmospheric widespread adoption of digital television
technology. These televisions featured
manual tuning controls, often in the form
 of rotary knobs or dials, which allowed Audio Detector
users to adjust the frequency to tune in - often referred to as an audio receiver or
to different channels audio sensor circuit
• Walkie-talkies (two-way radios) - is a fundamental electronic circuit
- two-way radios that allowed users to used to detect and process audio
manually select the operating frequency signals
or channel using a tuning dial. These - found in a wide range of applications,
including communication systems, audio
walkie-talkies were commonly used
equipment, security systems, and
before the advent of digital
automation systems
communication technologies and
featured analog tuning mechanisms.
________________________________________ Uses of Audio Detectors
DEVICES THAT USE AUTOMATIC TUNING • Signal Detection
• Modern Radios - The primary function of an audio
- These radios utilize digital tuner detector circuit is to detect audio
technology to automatically scan for and signals from various sources such as:
lock onto available radio stations or Microphones, radio receivers, audio
frequencies without requiring manual playback device
intervention from the user. Unlike older • Amplification
analog radios with manual tuning knobs, • Filtering
modern radios use digital tuners that
• Demodulation
can quickly scan through the radio
frequency spectrum and identify • Rectification
available stations. • Output
• Mobile Phones ____________________________________
- for selecting and connecting to cellular Audio Amplifiers
networks - Audio amplifiers are circuits in which audio
- automatically scans for available signals are amplified to the desired levels.
cellular networks in the vicinity - needed in radio transmission since the
• Modern Television audio signal decoded by the audio
- the TV automatically scans for available detector can be very faint and inaudible
channels. This scan involves the TV tuner - Amplification can be done internally or
externally (in the case of standalone audio
systematically tuning to different
amplifiers for large-scale purposes)
frequencies and detecting signals
broadcast by terrestrial, cable, or
satellite sources.
• GPS receivers
- The GPS receiver employs an auto-tuning
algorithm to scan the radio frequencies
used by GPS satellites and identify
available signals
- By analyzing the timing and strength of
signals received from multiple satellites,
the GPS receiver calculates its position,
velocity, and time using techniques such
as trilateration. Reproducers
____________________________________
 - These devices convert [electrical] audio
signal into sound waves through
electromagnetism.
- They have coils which act as electromagnets
when current passes through them.
- Basically, a motor that drives a membrane
back and forth to create sound waves.
_____________________________________________

PARTS OF A SPEAKER
• Permanent magnet
- A cylindrical magnet made of a strong
material like ferrite or neodymium. It
creates a steady magnetic field within
the speaker.
• Voice Coil
A thin cylinder of wire wrapped around a
former, typically made of aluminum or
copper. The voice coil sits in the gap between
the poles of the permanent magnet and
carries the electrical audio signal.
• Diaphragm
- A thin, flexible cone or dome-shaped
membrane, usually made of paper, metal,
or composite materials. The diaphragm is
attached to the voice coil and vibrates in
response to the changing current in the
coil, creating sound waves.