AM Double-sideband suppressed-carrier transmission (DSB-SC) is transmission

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AM Modulation Types

 

 

 

Mohammed Fareed Rafea, 201410181

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Yaqoob alrayes, 201320134

 

 

 

Ahlia University

Dr. Ayman Alaiwi

 

 

 

 

Abstract – Summarize your lab report:

–         
The research focus is to determine the different types
of AM Modulation by using Simulink.

–         
The research methods is converting a series of data
through AM    Modulation, (DSB-SC) and
(SSB).

–         
The results will be three figures which can show the
sine wave though modulation and the scopes of them with audio and carrier.

–         
Main conclusions, is what we learned from these
systems.

Index Terms – Amplitude Modulation (AM), (DSB-SC) and (SSB)

 

I.                  
INTRODUCTION

In this lab, we are going to use a sine wave to pass
through each modulation and observe the outcome from the transmitter. Modulation
is the procedure of converting a series of data to signals that can be
communicated over a communications medium.

A stable radio signal must be converted or
modulated in one way to carry
information, so that the information can be communicated from one place to
another.

II.               
LITERATURE REVIEW

Amplitude Modulation is the altering
the largeness of the carrier signal with respect to the instantaneous change in
message signal. The amplitude modulated waveform, its envelope and its
frequency spectrum and bandwidth. 

 

Double-sideband suppressed-carrier transmission (DSB-SC) is transmission in which frequencies shaped by amplitude modulation
(AM) are proportionally spread out above and below the carrier frequency and
the carrier level is reduced to the lowest practical level.

 

SSB modulation is a single
sideband, also a derivative of amplitude modulation. It is possible to improve
its efficiency, by removing some of the components of the ordinary AM signal. SSB is used for voice transmission,
but technically it can be used for many other applications. A typical AM
receiver involves Antenna, mast-head amplifier, co-axial cable, Low Noise
Amplifier (LNA), RF mixer, IF Amplifier, IF mixer, LPF, Audio Amplifier and Speaker.

 

III.            
EXPERIMENTAL PROCEDURE

By
following these procedures:

1.      Open MATLAB software

2.      Open Simulink software

3.      Open a “New model” 

4.      Save as “LAB4”

5.      Go to “Simulink” >> “Sources” and add
“Sine Wave”

6.      Go to “Simulink” >> “Sources” and add
“Chirp Signal”

7.      Go to “Signal Processing Block set”
>> “Signal Processing Sources” and add “Random Source”

8.      Go to “Simulink” >> “Sinks” and add
“Scope”

9.      Go to “Simulink” >> “Signal Routing”
and add “From” 10 times

10.  Go to “Simulink” >> “Signal Routing”
and add “Goto” 6 times

11.  Go to “Simulink” >> “Math Operations”
and add “Product” 2 times

12.  Go to “Simulink” >> “Math Operations”
and add “Sum”

13.  Go to “Simulink” >> “Math Operations”
and add “Gain” Twice

14.  Go to “Communication Blockset” >>
“Synchronization” >> “Components” and add “Continuous-Time VCO” 

15.  14- Go to “Signal Processing Blockset”
>> “Signal Processing Sinks” and add “Spectrum Scope” 3 times!

16.  Double click on “Spectrum Scope” and double
check the following parameters

17.  Go to “Simulink” >> “Discrete” and
add “Zero-Order Hold” TWICE!

18.  Double click on “Zero-Oder Hold” and check
the parameter as sampletime=20e-9

19.  Double-Click on the “Sine Wave” block and
check the parameters as Frequency=2*pi470e3 and sample time =20e-9

20.  Double-Click on the “Chirp Signal” block
and check the parameters as initial frequency=20, target time=5e-3, and
frequency at target time=20e3

21.  Double-Click on the “Random Source” block
and check the following parameters

22.  Double-Click on the “Continuous-Time VCO”
block and check the parameters as output amplitude=1, quiescent
frequency=470e3, input sensitivity=20e3 ,Initial phase=0

23.  Double-Click on the “Scope” block >>
then Click on “Parameters” and check the following parameters then click
“Apply” and “OK”

24.  Right-Click on the 1st Vertical Axis of
“Scope” window, then click on “Axes properties” and rename “Title” to be
“Audio”

25.  – Repeat Step 22 to rename the “Title” of
the other 4 Axes to be (Carrier, Full AM, DSB-SC, SSB) in order one by one

26.  Connect the blocks as shown below

27.  Double-Click on “Goto” blocks and rename
all of them with respect to the names shown in step 24.

28.  Double-Click on “From” blocks and click on
“Update Tags” then choose a corresponding tag from the “Goto Tag” drop-down
menu

 

 

IV.            
RESULTS AND DISCUSSION

Comparing the AM types in terms of
Sidebands (using the spectrum scope)

Figure 1: Full AM diagram

 

Figure 2: DSB-SC diagram

Figure 3: SSB diagram

Figure 4: Each type of wave inside a scope

Run the
simulation when you vary the Modulation Depth and note the differences between
the Full AM, DSB-SC and SSB signals in time-domain (using “Scope”)

Figure 5: Modulation Depth = 0.5

 

Figure 6: Modulation Depth = 1

Figure 7: Modulation Depth = 2

Double-Click on “Gain” block and set the “Gain” to: Gain = 1 Gain =
-1. Run the simulation and note the changes to SSB signal in frequency-domain

Figure 8: Gain=1 (scaled in) USB

Figure 9: Gain=0 (scaled in) LSB

 

V.               
CONCLUSION

In this test, we learned the differences between Full AM , DSB-SC and
SSB. We also learned how to frame what we took on lecture to a simple simulated
transmitter and receiver device using Simulink models.

 

 

VI.            
REFERENCES

1.      Anon, THEORY OF
AMPLITUDE MODULATION. BrainKart. Available at:
http://www.brainkart.com/article/Theory-of-Amplitude-Modulation_13077/
Accessed December 23, 2017.

2.      Anon,
DOUBLE-SIDEBAND SUPPRESSED-CARRIER TRANSMISSION (DSB-SC). BrainKart.
Available at: http://www.brainkart.com/article/Double-sideband-suppressed-carrier-transmission–DSB-SC-_13114/
Accessed December 23, 2017.

3.     
Electronics radio, Single Sideband Modulation, SSB. Electronics
Notes. Available at:
https://www.electronics-notes.com/articles/radio/modulation/single-sideband-ssb-basics.php
Accessed December 23, 2017.