Amplitude Modulation and Frequency Modulation Experiment - Assignment

Running head: AM AND FM EXPERIMENT 0
AM AND FM EXPERIMENT
Name of Student
Institution Affiliation

AM AND FM EXPERIMENT 2
AIM
To compare and contrast the amplitude modulation and Frequency modulation for both the
frequency domain and time domain.
Introduction
In a radio system, there are higher frequency signals of the sinewave which are modulated by
a message signal. These signals are as well referred to as carrier wave. This is achieved through
modulating it with a signal having a relatively lower frequency. This is very important because it
is challenging to convey the message signal in a straight line from the transmitter to the receiver.
Modulating signal may vary in three different types. All the types of the modulation are analog
and are employed in the transmission of the signal through wireless. And for any analog
modulator, there is always two input with just one output. These two inputs are the carrier signal
waveform and the analog signal to be transmitted while the output is the modulated output. We
will hence discuss these two types of modulations;
1. Frequency Modulation (FM)
2. Amplitude Modulation ( AM)

AM AND FM EXPERIMENT 3
Frequency Modulation (FM)
In this form of modulation the carrier frequency changes due to the analog baseband
info signal ready to be conveyed via wireless devices. This modulation is essentially treated to be
better than the AM because it of better noise immunity it has and its capacity to reject the
interfering signals because of the capture effect. The equation below help to obtain modulation
depth
m= Δf
fm ..................................................................................................i
Where Δf is the frequency deviation and fm is the frequency of the modulating signal.
For the FM the value of m defines the amplitude of different frequency component in the FM
spectrum.The amplitudes in the FM are related to the Basel function values. Figure 1 below
illustrates the spectrum of FM signal;
Fig 1: Showing the spectrum of FM signal

AM AND FM EXPERIMENT 4
The utmost common technique of applying modulation to a signal is by
overlaying the audio signal onto the amplitude of the carrier. When employing
frequency modulation, extra advancements in signal to noise ratio can be realized
only if the audio signal is stressed. To obtain this there must be an amplification of
lower level high frequency sounds to a higher degree than the lower frequency
sounds before they are conveyed. As soon as the receiver the signals are passed via
a network with the reverse effect to reinstate a flat response frequency.
The transmitter and receiver networks must match one another. For
broadcasting in North America values of 75μs with a break frequency of 2.1 kHz is
used. Frequency modulation is used in a wide variety or radio communications
applications from broadcasting to two-way radio communications links as well as
mobile radio communications. It possesses many advantages over amplitude
modulation and this is the reason for its widespread use. Nowadays, many digital
forms of radio communications are being introduced, but despite this the use of
frequency modulation, FM will undoubtedly continue for many years to come in
many areas of radio communications.
Equipment
1. Spectrum Analyser- Rhode & Schwarz HMS-X
2. Oscilloscope- Keysight Infiniivision DSO- X 2002A, 70 MHz, 2GGSa/sec, Digital
Storage Oscilloscope (DSO).
3. Waveform Generator – Keysight 33500B.
Procedure