What is Radio FM and AM?What is Radio FM and AM?
By: Mohammad JobairBy: Mohammad Jobair
Agenda:Agenda:
•What is Radio ?
•What is AM and FM?
•What is the Difference between AM and FM
Radio?
What is Radio:What is Radio:
Radio is a small part of the electromagnetic spectrum that is
used for a wide range of business and nonbusiness
purposes.
The Electromagnetic Spectrum The Electromagnetic Spectrum
The electromagnetic spectrum is a continuum of all
electromagnetic waves arranged according to frequency and
wavelength.
Electromagnetic energy:Electromagnetic energy:
is a term used to describe all the different kinds of energies
released into space by stars such as the Sun. These kinds of
energies include some that you will recognize and some that
will sound strange. They include:
Radio Waves
TV waves
Radar waves
Heat (infrared radiation)
Light
Ultraviolet Light (This is what causes Sunburns)
Xrays (Just like the kind you get at the doctor's office)
Short waves
Microwaves, like in a microwave oven
All these waves do different things (for example, light waves
make things visible to the human eye, while heat waves
make molecules move and warm up, and x rays can pass
through a person and land on film, allowing us to take a
picture inside someone's body) but they have some things in
common.
AM Radio: AM Radio:
Amplitude Modulation (AM)Amplitude Modulation (AM)
•Amplitude modulation is the process of
varying the amplitude of a carrier wave
in proportion to the amplitude of a
baseband signal. The frequency of the
carrier remains constant.
•Modulation is the process of impressing a low
frequency information signal (baseband
signal) onto a higher frequency carrier signal.
The term baseband is used to designate the band of
frequencies representing the original signal as delivered by
the input transducer
For example, the voice signal from a microphone is a
baseband signal, and contains frequencies in the range
of 03000 Hz
The “hello” wave is a baseband signal:
pressure modulation (sound)
electromagnetic wave modulation
Amplitude Modulation (AM) uses changes in the signal strength to
convey information
Pressure modulation (sound)
electromagnetic wave modulation
Frequency Modulation (FM) uses changes in the wave’s frequency to
convey information
AM vs. FMAM vs. FM
AM requires a simple circuit, and is very easy to generate.
It is simple to tune, and is used in almost all short wave
broadcasting.
The area of coverage of AM is greater than FM (longer
wavelengths (lower frequencies) are utilizedremember property
of HF waves?)
However, it is quite inefficient, and is susceptible to static and
other forms of electrical noise.
The main advantage of FM is its audio quality and immunity
to noise. Most forms of static and electrical noise are naturally
AM, and an FM receiver will not respond to AM signals.
The audio quality of a FM signal increases as the frequency
deviation increases (deviation from the center frequency), which
is why FM broadcast stations use such large deviation.
The main disadvantage of FM is the larger bandwidth it
requires
Difference between AM and FMDifference between AM and FM
1: AM radio is a Amplitude modulation but FM is a Frequency 1: AM radio is a Amplitude modulation but FM is a Frequency
modulation.modulation.
2: FM can be filtered out when the tune received by receiver but in AM 2: FM can be filtered out when the tune received by receiver but in AM
not.not.
3: The AM signal can be changed And difficult to get information form it 3: The AM signal can be changed And difficult to get information form it
but in FM is constant.but in FM is constant.
4: AM is taken In low Frequency and not stereo but FM taken in high 4: AM is taken In low Frequency and not stereo but FM taken in high
frequency and its stereo.frequency and its stereo.
5: AM can received as a analog but FM can be received as Digital.5: AM can received as a analog but FM can be received as Digital.
6: The Amplitude of Income will be muted in FM if its not that much 6: The Amplitude of Income will be muted in FM if its not that much
strong enough, but in AM whether its strong or not.strong enough, but in AM whether its strong or not.