Lab Report#10
Communication System
By:
Umar farooq
COMMUNICATION SYSTEM
Submitted by:
Umar Farooq
Reg# 20MDTLE080
Department: Telecommunication
Section: A
Submitted To:
Engr. Humaira Rehman
Due date:
30th Dec 2022
COMMUNICATION SYSTEM
LAB # 10: Designing of Analyzing Frequency
Modulation
Learning Objectives:
To understand the theoretical foundations for Angle Modulation as well as Frequency
Modulation (FM) and Demodulation
2. To implement the Simulink models for FM including a basic sinusoid and a multimedia file
(music) to analyze each signal in time and frequency domains using time scope and
spectrum analyzer
3. To examine the effects of the Additive Gaussian Channel (AWGN) in the Simulink for FM
4. To observe the real-time music transmission for a FM modulated music file via USRP
trans-receiver
1.
Required Software:
The required software is “Simulink MATLAB”.
introduction:
Amplitude modulation:
Amplitude modulation was the first modulation type to be considered in analog communication
systems. Amplitude modulation has the obvious advantage of being simple and relatively
bandwidth efficient. The disadvantages of amplitude modulation are [1]:
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Since the message is embedded in the amplitude of the carrier signal, the cost,
performance, and the size of the linear amplifiers are difficult to accomplish for obtaining
fair performance in AM systems.
When the message goes through a quiet period in Double Side Band (DSB) or Single Side
Band (SSB) systems, very small carrier signals are transmitted. The absence of the signal
tends to accentuate the noise.
The passband bandwidth is small compared to the other modulation schemes, i.e. FM,
cellular, Wi-Fi etc.
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Amplitude modulation or AM as it is often called, is a form of modulation used for radio
transmissions for broadcasting and two-way radio communication applications. Although it is
one of the earliest used forms of modulation, it is still used today, mainly for long, medium and
short-wave broadcasting and for some aeronautical point to point communications, but very
few other applications. One of the key reasons for the use of amplitude modulation was its ease
of use. The system simply required the carrier amplitude to be modulated, but more usefully
the detector required in the receiver could be a simple diode-based circuit.
This factor meant that AM radios did not need complicated demodulators and costs were
reduced - a key requirement for widespread use of radio technology, especially in the early
days of radio when ICs were not available.
History of frequency modulation:
he history of FM dates back to 1936 when Edwin Howard Armstrong described the FM frequency
as a method of reducing disturbances in radio transmission in a conference of Radio Engineers
New York in November 6, 1936. FM frequency is widely used in telecommunication devices to
transmit voice without disturbances.
Process:
A continuous-wave goes on continuously without any intervals and it is the baseband message
signal, which contains the information. This wave has to be modulated.
According to the standard definition, “The amplitude of the carrier signal varies in accordance
with the instantaneous amplitude of the modulating signal.” Which means, the amplitude of the
carrier signal containing no information varies as per the amplitude of the signal containing
information, at each instant. This can be well explained by the following figures.
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MATLAB code:
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Output wave form:
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Simulink Fm modulation:
Output wave form:
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Practical work:
Practical observation:
Practical input:
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Practical output:
conclusions:
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After performing this lab, we become familiar with frequency modulation in more details and
we performed experiment on frequency modulation practically in which we got familiarized
with new lab equipment’s such as FM modulating circuit.